Stress Analysis INVENTOR

Contents

Chapter 1

Part Modal and Stress Analysis . . . . . . . . . . . . . . . . . . . 1 Simulation 1: About this tutorial . . . . . . . . . . . . . . . . . . . . . . 1 Open the Model for Modal Analysis . . . . . . . . . . . . . . . . . . . . 3 Enter the Stress Analysis Environment . . . . . . . . . . . . . . . . . . . 3 Assign Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Add Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Preview Mesh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Run Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 View the Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Summar y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Simulation 2: About this tutorial . . . . . . . . . . . . . . . . . . . . . 12 Copy Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Create Parametric Geometry . . . . . . . . . . . . . . . . . . . . . . . 14 Include Optimization Criteria . . . . . . . . . . . . . . . . . . . . . . . 16 Add Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Set Convergence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Run Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 View the Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Summar y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Chapter 2

Assembly Stress Analysis . . . . . . . . . . . . . . . . . . . . . 23 About this tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Get Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

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Stress Analysis Environment . . Excluding Components . . . . . Assign Materials . . . . . . . . . Add Constraints and Loads . . . Stress Analysis Settings . . . . . Contact Conditions . . . . . . . Generate Meshes . . . . . . . . Run the Simulation . . . . . . . View and Interpret the Results . Summar y . . . . . . . . . . . .

Chapter 3

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. 39 . 40 . 41 . 41 . 42 . 42 . 43 . 46 . 50 . 51 . 51 . 54 . 54 . 56 . 57 . 59

Assembly Modal Analysis . . . . . . . . . . . . . . . . . . . . . 61 About this tutorial . . . . . . . . . . Open the Assembly . . . . . . . . . Create a Simulation Study . . . . . . Exclude Components . . . . . . . . Assign Materials . . . . . . . . . . . Add Constraints . . . . . . . . . . . Create Manual Contacts . . . . . . . Specify Mesh Options . . . . . . . . Preview Mesh and Run Simulation . View and Interpret Results . . . . . Summar y . . . . . . . . . . . . . .

Chapter 5

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Contacts and Mesh Refinement . . . . . . . . . . . . . . . . . 39 About this tutorial . . . . . . . . . . . Open the Model . . . . . . . . . . . . Stress Analysis Environment . . . . . Create a Simulation . . . . . . . . . . Exclude Components . . . . . . . . . Assign Materials . . . . . . . . . . . . Add Constraints and Loads . . . . . . Define Contact Conditions . . . . . . Specify and Preview Meshes . . . . . . Run the Simulation . . . . . . . . . . View and Interpret the Results . . . . Copy and Modify Simulation . . . . . Specify Local Mesh Controls . . . . . Run the Simulation Again . . . . . . . View and Interpret the Results Again . Summar y . . . . . . . . . . . . . . .

Chapter 4

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. 62 . 64 . 65 . 66 . 67 . 67 . 68 . 70 . 70 . 71 . 73

FEA Assembly Optimization . . . . . . . . . . . . . . . . . . . . 75 About this tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

ii | Contents

Open the Assembly . . . . . . . Define the Simulation . . . . . . Assign Materials . . . . . . . . . Adding Constraints . . . . . . . Adding Loads . . . . . . . . . . Modify the Mesh . . . . . . . . Preview the Mesh . . . . . . . . Create Parametric Geometry . . Optimization Criteria . . . . . . Run the Simulation . . . . . . . View and Interpret the Results . View and animate 3D plots . . . View XY Plots . . . . . . . . . . Summar y . . . . . . . . . . . .

Chapter 6

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. 77 . 77 . 78 . 78 . 79 . 80 . 81 . 82 . 84 . 85 . 85 . 87 . 88 . 90

Stress Analysis Contacts . . . . . . . . . . . . . . . . . . . . . . 93 About this tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Open the Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 How a Caulk Gun Works . . . . . . . . . . . . . . . . . . . . . . . . . 96 Assembly Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Contact Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 Bonded Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Separation Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Sliding and No Separation Contact . . . . . . . . . . . . . . . . . . . 104 Separation and No Sliding Contact . . . . . . . . . . . . . . . . . . . 107 Shrink Fit and No Sliding Contact . . . . . . . . . . . . . . . . . . . . 108 Spring Contact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Loads and Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Simulation Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

Chapter 7

Frame Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 117 About this tutorial . . . . . . . . . . Open the Assembly . . . . . . . . . Frame Analysis Environment . . . . Frame Analysis Settings . . . . . . . Assign Materials . . . . . . . . . . . Change Beam Properties . . . . . . . Change Direction of Gravity . . . . . Add Constraints . . . . . . . . . . . Add Constraints to the Next Beam . Add Loads . . . . . . . . . . . . . . Run the Simulation . . . . . . . . . View and Interpret Results . . . . . .

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. 117 . 119 . 119 . 122 . 122 . 124 . 124 . 125 . 128 . 129 . 131 . 132

Contents | iii

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

Chapter 8

Frame Analysis Results . . . . . . . . . . . . . . . . . . . . . . 135 About this tutorial . . . . . . . . . . . . . Get Started . . . . . . . . . . . . . . . . . Frame Analysis Environment . . . . . . . View and Interpret the Results . . . . . . . Display Maximum and Minimum Values . View Beam Detail . . . . . . . . . . . . . Display and Edit Diagrams . . . . . . . . . Adjust Displacement Display . . . . . . . Animate the Results . . . . . . . . . . . . Generate Report . . . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . . .

Chapter 9

iv | Contents

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. 149 . 150 . 151 . 152 . 154 . 154 . 157 . 159 . 160 . 164 . 165 . 166 . 167 . 169 . 170 . 171

Modal Type of Frame Analysis . . . . . . . . . . . . . . . . . . 173 About this tutorial . . . . . . . Open the Assembly . . . . . . Frame Analysis Environment . Create a Simulation Study . . . Run the Simulation . . . . . . View the Results . . . . . . . . Animate the Results . . . . . . Summary . . . . . . . . . . . .

Chapter 11

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Frame Analysis Connections . . . . . . . . . . . . . . . . . . . 149 About this tutorial . . . . . . . . Connections Overview . . . . . . Open the Assembly . . . . . . . Frame Analysis Environment . . Change Direction of Gravity . . . Add Custom Nodes . . . . . . . Add Custom Nodes . . . . . . . Change Color of Custom Nodes . Assign Rigid Links . . . . . . . . Add Constraints . . . . . . . . . Run the Simulation . . . . . . . View the Results . . . . . . . . . Assign a Release . . . . . . . . . Run the Simulation Again . . . . View the Updated Results . . . . Summary . . . . . . . . . . . . .

Chapter 10

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. 173 . 175 . 175 . 175 . 176 . 177 . 178 . 179

Dynamic Simulation - Part 1 . . . . . . . . . . . . . . . . . . . 181

About this tutorial . . . . . . . . . . Open the Assembly . . . . . . . . . Degrees of Freedom . . . . . . . . . Automatic Constraint Conversion . . Assembly Constraints . . . . . . . . Add a Rolling Joint . . . . . . . . . . Building a 2D Contact . . . . . . . . Add Spring, Damper, and Jack Joint . Define Gravity . . . . . . . . . . . . Impose Motion on a Joint . . . . . . Run a Simulation . . . . . . . . . . . Using the Output Grapher . . . . . . Simulation Player . . . . . . . . . . Summary . . . . . . . . . . . . . . .

Chapter 12

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Dynamic Simulation - Part 2 . . . . . . . . . . . . . . . . . . . 205 About this tutorial . . . . . . . . . . . Work in the Simulation Environment . Construct the Operating Conditions . Add Friction . . . . . . . . . . . . . . Add a Sliding Joint . . . . . . . . . . . Use the Input Grapher . . . . . . . . . Use the Output Grapher . . . . . . . . Export to FEA . . . . . . . . . . . . . . Publish Output in Inventor Studio . . Summary . . . . . . . . . . . . . . . .

Chapter 13

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. 205 . 206 . 208 . 210 . 212 . 213 . 217 . 219 . 223 . 225

Assembly Motion and Loads . . . . . . . . . . . . . . . . . . . 227 About this tutorial . . . . . . . . . . . . . Open Assembly . . . . . . . . . . . . . . . Activate Dynamic Simulation . . . . . . . Automatic Joint Creation . . . . . . . . . Define Gravity . . . . . . . . . . . . . . . Insert a Spring . . . . . . . . . . . . . . . Define the Spring Properties . . . . . . . . Run the Simulation . . . . . . . . . . . . Insert a Contact Joint . . . . . . . . . . . Edit the Joint Properties . . . . . . . . . . Add Imposed Motion . . . . . . . . . . . View the Simulation Results . . . . . . . . View the Simulation Results (continued) . Export the Data . . . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . . .

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Contents | v

Chapter 14

FEA using Motion Loads . . . . . . . . . . . . . . . . . . . . . 245 About this tutorial . . . . . . . . . . . . Open Assembly File . . . . . . . . . . . Run a Simulation . . . . . . . . . . . . . Generate Time Steps . . . . . . . . . . . Export to Stress Analysis . . . . . . . . . Use the Motion Loads in Stress Analysis . Generate a report . . . . . . . . . . . . . Summary . . . . . . . . . . . . . . . . .

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. 246 . 247 . 249 . 249 . 249 . 253 . 256 . 257

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

vi | Contents

Part Modal and Stress Analysis

1

Simulation 1: About this tutorial

Modal analysis. Category

Simulation

Time Required

20 minutes

1

Tutorial Files Used

PivotBracket.ipt

You will create two simulations: modal analysis of the part and a parametric structural static analysis on the same part. The Modal Analysis tutorial walks through the process of defining and performing a structural frequency analysis, or modal analysis, for a part. The simulation generates the natural frequencies (Eigenvalues) and corresponding mode shapes which we view and interpret at the end of the tutorial. The second simulation is a parametric study on the same model. Parametric studies vary the design parameters to update geometry and evaluate various configurations for a design case. We perform a structural static analysis with the goal of minimizing model weight. Objectives ■ Create a simulation for modal analysis ■

Override the model material with a different material

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Specify constraints

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Run the simulation

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View and interpret the results

Prerequisites ■ Familiarity with the ribbon user interface and Quick Access Toolbar. ■

Familiarity with the use of the model browser and context menus.

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See the Help topic “Getting Started” for further information.

Navigation Tips ■ Use Show in the upper-left corner to display the table of contents for this tutorial with navigation links to each page. ■

Use Forward in the upper-right corner to advance to the next page.

Next (page 3)

2 | Chapter 1 Part Modal and Stress Analysis

Open the Model for Modal Analysis Let’s get started on the Modal Analysis simulation first. 1 On the Quick Access Toolbar, click the Open command. 2 Set your project file to Tutorial_Files.ipj if not already set. 3 Select the part model named PivotBracket.ipt. 4 Click Open. Previous (page 1) | Next (page 3)

Enter the Stress Analysis Environment The stress analysis environment is one of a handful of Inventor environments that enable specialized activity relative to the model. In this case, it incorporates commands for doing part and assembly stress analysis. To enter the stress analysis environment and start a simulation: 1 Click the Environments tab in the ribbon bar. The list of available environments is presented.

2 Click the Stress Analysis environment command.

3 Click Create Simulation. 4 The Create New Simulation dialog box displays. Specify the name Modal Analysis. 5 In the Simulation Type tab, select Modal Analysis. 6 Leave the remaining settings in their current state and click OK. A new simulation is started and the browser is populated with stress analysis-related folders. Previous (page 3) | Next (page 4)

Open the Model for Modal Analysis | 3

Assign Material For any component that you want to analyze, check the material to make sure that it is defined. Some Inventor materials do not have “simulation-ready” properties and need modification before using them in simulations. If you use an inadequately defined material, a message displays. Modify the material or select another material. You can use different materials in different simulations and compare the results in a report. To assign a different material: 1 In the ribbon bar, in the Material panel, click Assign Materials.

2 Click in the Override Material column to activate the drop-down list. 3 Select Aluminum-6061. 4 Click OK. NOTE Use the Styles and Standards Editor to modify materials if they are not completely defined. You can access the editor from the lower left corner of the Assign Materials dialog box. Previous (page 3) | Next (page 4)

Add Constraints Next, we add the boundary conditions, a single constraint on the interior cylindrical face. To add the constraint: 1 In the ribbon bar, in the Constraints panel, click the Fixed Constraint command. The docked dialog box displays. 2 Select the face as shown.


3 Click OK. The model is now constrained by that face. The browser constraints folder is populated with a node representing the constraint. Previous (page 4) | Next (page 6)

Add Constraints | 5

Preview Mesh

Before starting the simulation, we can view the mesh. 1 In the ribbon bar, Prepare panel, click Mesh View. The command is a toggle between model view and mesh view. 2 To return to the model, click Mesh View again. Previous (page 4) | Next (page 7)


Run Simulation Now, to run the simulation. 1 In the Solve panel, click the Simulate command to display the Simulate dialog box. 2 Check the More section of the dialog box for messages. Click Run to display the simulation progress. Wait for the simulation to finish. Previous (page 6) | Next (page 7)

View the Results After the simulation finishes, the Results folder populates with the various results types. The graphics region displays the first mode shaded plot. In the browser under the Results node and then the Modal Frequency node, notice the first mode shape (F1) has a check mark by it, indicating it is being displayed. There are nodes for the mode shapes corresponding to each natural frequency. The color chart shows relative displacement values. The units are not applicable since the mode shapes values are relative. (They have no actual physical value at this point.) Now you can perform post-processing tasks using the Display commands located on the ribbon bar. The commands are described in Help.

Run Simulation | 7

For post-processing of structural frequency simulation studies, the browser list shows the natural frequencies. Double-click any of these nodes to show the corresponding Mode Shape 3D plot. 1 Animate the results using the Animate Results command in the Result panel on the ribbon bar. 2 While the animation is playing, click Orbit in the navigation tools on the side of the graphics window. As you orbit the graphics, the animation continues to play. NOTE The following image depicts a frame from the animation of mode F3.


3 Click OK. 4 In the Results browser list of natural frequencies, double-click the results for mode F3 to display that mode.

View the Results | 9


NOTE If you plan to complete the second part of this tutorial, keep this model file open. Otherwise, save your model file to a different name before you close it. Previous (page 7) | Next (page 11)

Summary

In this first tutorial for Part Stress Analysis, you learned how to: ■ Create a simulation for modal analysis. ■

Override the model material with a different material.

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Specify constraints.

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Run the simulation.

■

View and interpret the results.

What Next? Continue with “Simulation 2 - Parametric Static Analysis” Previous (page 7) | Next (page 12)

Summary | 11

Simulation 2: About this tutorial


Parametric static analysis. Skill Level

Level 3 special interest

Time Required

20 minutes

Tutorial Files Used

PivotBracket.ipt

The second simulation is a parametric study on the same model. Parametric studies vary the parameters of the model to update geometry and evaluate various configurations of a design. In this structural static analysis, the goal is to minimize the weight of the model. Objectives ■ Copy a simulation. ■

Use analysis parameters to evaluate how to refine the weight of the model.

■

Generate configurations of the parametric dimension geometry.

■

Modify design constraints and view results based on those changes.

Prerequisites ■ Completed Simulation 1 (Modal Analysis), the first part of this tutorial set. ■


Navigation Tips ■ Use Show in the upper-left corner to display the table of contents for this tutorial with navigation links to each page. ■

Use Forward in the upper-right corner to advance to the next page.

Previous (page 11) | Next (page 13)

Copy Simulation We will create a copy of the first simulation, and edit it to define the second analysis. 1 In the browser, right-click the Simulation (Modal Analysis) node and click Copy Simulation. A copy of this simulation is added to the browser and becomes the active simulation.

Copy Simulation | 13

We will edit the simulation properties to define a parametric dimension study. 2 Right-click the newly created Simulation node, and click Edit Simulation Properties. 3 Change the name to Parametric. 4 Change the Design Objective to Parametric Dimension using the drop-down list. 5 Set the simulation type to Static Analysis. 6 Click OK. Previous (page 12) | Next (page 14)

Create Parametric Geometry We will produce a range of geometric configurations involving the thickness of the model to facilitate weight optimization. Adding parameters to the parametric table is required. Add parameters to the parametric table 1 In the Manage panel, click Parametric Table. 2 In the browser, right-click the part node just below the Simulation (Parametric) node, and click Show Parameters. 3 In the Select Parameters dialog box, check the box to the left of the parameter named d2, 12 mm. 4 Click OK. After identifying the parameter we want to use, we must define a range for the parameter and generate the corresponding geometric configurations. Define parameter range 1 In the Values cell for Extrusion1 d2, enter the range 6-12. The values must be in ascending order. 2 Press Enter to accept the values. When you click inside the Value field, the value now says 6-12:3. This indicates that there are now three values in the range. These are equally divided between the first and last number, hence that values are 6, 9, and 12.


NOTE The number after the colon specifies the additional configurations desired, excluding the base configuration. The base is 12 mm, and the two additional configurations are 6 mm and 9 mm. Once the parameter range is specified, we can generate the various configurations based on the range values. Generate configurations 1 Right-click the table parameter row, and select Generate All Configurations. The model generation process is started. 2 After the model regeneration is completed, move the slider to see the different shapes created.

Create Parametric Geometry | 15

We are not finished with the Parametric Table yet, so do not close it. Previous (page 13) | Next (page 16)

Include Optimization Criteria Remember that our goal for this simulation is to minimize weight. We optimize the simulation using a range of geometric configurations generated previously while utilizing the Yield Strength failure criteria. Add Design Constraints 1 In the Design Constraints section, pause the cursor over the empty row, right-click, and click Add Design Constraint. 2 In the Select Design Constraint dialog box, click Mass, and click OK. 3 Repeat step 1. 4 In the Select Design Constraint dialog box, Select Von Mises Stress. Ensure that Geometry Selections is All Geometry. 5 Click OK. Enter Limit values and safety factor 1 In the Von Mises Stress row, click in the Constraint type cell, and select Upper Limit from the drop-down list. 2 Enter 20 for Limit. 3 Enter 1.5 for Safety Factor . Previous (page 14) | Next (page 16)

Add Loads Next, add the structural load. 1 Click the Force Load command. The dialog box displays. 2 Select the face as shown.


3 Enter 200 N for the Magnitude. 4 Click OK. Previous (page 16) | Next (page 17)

Set Convergence The software performs an automatic H-P refinement for parts. In this case, we want to add an additional H refinement iteration. H refinement increases the number of mesh elements in areas where the results need improvement. The P refinement increases the polynomial degree of the selected elements in the high stress areas to improve the accuracy of the results. 1 In the Prepare panel, click Convergence Settings. 2 For Maximum Number of h Refinements, enter 1. 3 Click OK. Previous (page 16) | Next (page 18)

Set Convergence | 17

Run Simulation Now we will run the simulation. To start the Simulation, use the Simulate command in the ribbon bar or through the simulation node context menu. 1 Click the Simulate command to display the Simulate dialog box. 2 Click Run. The Simulation progress displays. Wait for the simulation to finish. When the simulation is complete, the Von Mises Stress plot displays by default. 3 In the Display panel, click Adjust Displacement Display drop-down list, and select Actual.



,

View the Results After the simulation finishes, the graphics region displays a 3D color plot, and you can see that the Result folder is populated. Now we can evaluate the results through the parametric table and the 3D and XY plots available for post processing. Optimize model First, we optimize the mass using the parametric table populated in previous steps. Then we look at 3D and XY plots to understand the behavior of the model under the defined boundary conditions. The goal is to minimize the mass of the model taking into account parametric dimensions and stress constraints. 1 If you previously closed the Parametric table, reopen it by clicking the Parametric Table command. 2 For the Mass Design Constraint, click in the Constraint Type cell, and select Minimize from the drop-down list. The parametric values change to show the configuration with the least mass that meets the given constraints. In this case, the original thickness value was 12 mm and the optimized value is 9 mm which in turn reduces the mass of the model. Note the design constraint Result Value for Max Von Mises Stress. The value has a green circle preceding it. It indicates that the design constraint value is within the safety factor range. Slide the Extrusion1 parameter value to 6. When the table updates, you will see that the design constraint Result Value is now outside the safety factor. The value is preceded by a red square indicating the design constraint value has been exceeded the safety factor. Slide the parameter value back to 9. View and animate 3D plots Now you can perform post-processing tasks using the Display panel commands for smooth shading, contour plots, etc. These commands are described in Help. 1 In the Result panel, click Animate Results.

2 In the Animate dialog box, click the Play command. The Von Mises Stress plot colors change to reflect the application of the load. To


view the deformation changes, stop the animation, select Adjusted x1 from the Adjust Displacement Display restart the animation.

, drop-down list and

For post-processing of results, double-click the result in the browser to display the result in the graphics region. Then, select the Display command you want to use. View XY graphs XY Charts show a result component over the range of a parameter. To view an XY plot, right-click over the parameter row in the Parametric Table and choose XY Plot.

In this case, the above XY plot displays Stress results versus parametric configurations. Previous (page 18) | Next (page 21)


Summary

In this last tutorial for Part Stress Analysis, you learned how to: ■ Copy a simulation. ■

Modify the simulation properties to change the type of simulation.

■

Generate configurations of the parametric dimension geometry.

■

Use analysis parameters to evaluate how to refine the weight of the model.

■

Modify design constraints and view results based on those changes.

What Next? As a next step, consider doing the Assembly FEA tutorials. If you have already completed them, why not acquaint yourself with the Dynamic Simulation tutorials? Experiment with what you have seen and used. Explore how you can use this design tool to help you complete your digital prototype with confidence in its performance. Previous (page 19)

Summary | 21

22

Assembly Stress Analysis

2

About this tutorial

Simulate the structural static behavior of an assembly for analysis. Category

Simulation

Time Required

35 minutes

23

Tutorial File Used

analyze-2.iam

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. The stress analysis environment is a special environment within assembly, part, sheet metal, and weldment documents. The environment has commands unique to its purpose. We analyze a subset of an assembly using the “exclude from simulation” functionality in Stress Analysis. Contact types are changed as required by the physical behavior of the model. Meshing settings are adjusted to capture the geometry of the model more accurately. Objectives ■ Create a simulation. ■

Evaluate and assign materials as needed.

■

Add loads and constraints.

■

Identify contact conditions.

■

Create a mesh.

■

Run a simulation.

■


Prerequisites ■ Know how to use the Quick Access toolbar, tabs and panels on the ribbon, model browser, and context menus. ■

Know how to navigate the model space with the various view tools.

■

Know how to specify and edit project files.

■


Navigation Tips ■ Use Next or Previous at the bottom-left to advance to the next page or return to the previous one. Next (page 25)

24 | Chapter 2 Assembly Stress Analysis

Get Started To begin with, we will open the assembly to analyze. With Autodesk Inventor up and running, but with no model open, do the following: 1 Click the Open

command on the Quick Access toolbar.

2 Set the Project File to Tutorial_Files.ipj 3 Select Assembly FEA 1 ➤ analyze-2.iam. 4 Click Open. 5 Save the file with a different name, such as: analyze-2_tutorial.iam Previous (page 23) | Next (page 25)

Stress Analysis Environment We are ready to enter the stress analysis environment. 1 On the ribbon, click Environments tab ➤ Begin panel ➤ Stress

Analysis

.

2 On the Manage panel, click the Create Simulation The Create New Simulation dialog box displays.

command.

The settings provide opportunity to tailor the simulation by specifying a unique name, single point or parametric dimension design objective, and other parameters. NOTE On the Model State tab, you specify the Design View, Positional, and Level of Detail to use for the simulation. The settings can be different for each simulation. 3 Click OK to accept the default settings for this simulation. The browser populates with a hierarchical structure of the assembly and analysis-related folders. Most of the commands in the ribbon panels are now enabled for use. Disabled commands enable as their use criteria is satisfied.

Get Started | 25


Excluding Components You can exclude components that are not affected by the simulation or whose function is simulated by constraints or forces. We will exclude the following parts from this simulation: ■ Handle ■

Screw

■

SHCS_10-32x6

To exclude these components: 1 Expand the analyze-2_tutorial.iam browser node. 2 Right-click Handle, and click Exclude From Simulation. 3 Repeat the command for both the Screw and SHCS_10-32x6 components. The default display setting for excluded components is partially transparent as seen in the following image:



Assign Materials The next step is to look at the component materials and make adjustments. For this simulation, we will make a minor material change using materials that are fully defined. Before you begin doing simulations, we recommend that you ensure your material definitions are complete for those materials being analyzed. When a material is not completely defined, the material list displays a symbol next to the material name. If you try to use the material, you receive a warning message. If you attempt to edit a material during this tutorial, you may not be able to if the project setting Use Styles Library is set to No. To edit this setting, you cannot be working in the model. To change the setting requires exiting

Assign Materials | 27

the tutorial. For purposes of this tutorial, use a material that is already fully defined. You can modify the other materials at a later time.

1 In the Material panel, click the Assign command. The dialog box displays the list of components, their material assignments, an override material, and a column showing how the material safety factor is defined. 2 In the Override Material column, click the first component (Upper_Plate:1) cell to expose the material list. 3 In the list, click Steel. 4 Repeat the process for the all instances of the Upper and Lower plates. Notice that when a components material is changed, all instances of that component inherit the change. 5 Click OK to exit the Assign Materials dialog box. The browser Material folder receives a Steel folder added with all the components referencing that material listed within that folder. If you delete individual components from the folder, their material reverts to the assembly assigned material. Previous (page 26) | Next (page 28)

Add Constraints and Loads Next we define the boundary conditions by adding structural constraints and loads. We start with constraints first.

1 In the Constraints panel, click Fixed with the Location selector active.

. The dialog box displays

2 Select the two holes through which the screw passed. They are the holes that are left after excluding the screw from the simulation.


3 Click OK. The two faces are axially constrained, as if the screw were there.

Add Constraints and Loads | 29

Now, we assign loads on the components.

1 In the Loads panel, click Force the Location selector active.

. The dialog box displays with

2 Select the face on the ch_09-Upper_Grip component as shown.

3 In the dialog box, enter 100 for the Magnitude value, and click OK. 4 Repeat the previous steps for the ch_09-Lower_Grip component.


5 Click OK to exit the Force dialog box. Previous (page 27) | Next (page 31)

Stress Analysis Settings Stress Analysis settings apply to all new simulations. It is where you define the default settings that you saw in the Simulation Properties at the beginning of this process.

Stress Analysis Settings | 31

In the Settings dialog box, you can specify: ■ Simulation Type ■

Design Objective

■

Contact Defaults

■

Excluded Component Display

■

Other parameters

Though we will not change the defaults for this tutorial, it is good to familiarize yourself with these settings. You can modify them for your future needs. Previous (page 28) | Next (page 32)

Contact Conditions You can specify contact conditions either automatically or manually. Automatic contacts are generated according to the tolerance and contact type specified in the Stress Analysis Settings. You can assign other contact types such as Separation, Sliding / No Separation, and so on. For this simulation, we automatically compute inferred contacts and then change some of those to another type.

1 In the Contacts panel, click Automatic . It detects the contacts within the default tolerance and populates the Contacts folder. 2 Expand the Contacts folder. You can see that all contacts were created as Bonded contacts (default setting) and placed in a folder. Expand the Bonded folder. 3 We must change the contacts listed in the following list. To make changes, use multi-select. Select one contact, hold down the Ctrl key, and multi-select the remaining contacts in this list. ■ Bonded:1 (Upper Plate:1, Lower Plate:1) ■

Bonded:6 (Upper Plate:1, Pin A:3)

■


■

Bonded:10 (Upper Plate:1, Pivot Threaded:1)

■


■

Bonded:12 (Upper Plate:2, Lower Plate:2)


■


■


■


■


■

Bonded:26 (Lower Plate:1, Pivot Lower:1)

■


■


■

Bonded:32 Lower Plate:2, Pivot Lower:1)

4 Right-click a selected contact, and click Edit Contact. 5 Change the type to Sliding / No Separation, and click OK. Previous (page 31) | Next (page 33)

Generate Meshes Before running the simulation, view the mesh to make sure that any areas needing a different mesh setting from the default are cared for. First, we will specify the mesh settings.

1 In the Prepare panel, click Mesh Settings . Alternatively, right-click the Mesh folder and click Mesh Settings. 2 Set Maximum Turn Angle = 30 to capture round areas of the geometry. 3 Check Create Curved Mesh Elements. 4 If not already checked, check Use part based measure for assembly mesh. This option uses the part size as mesh criteria, as opposed to a single size for all parts. 5 Click OK. 6 Having specified the mesh settings, you preview the mesh by clicking

the Mesh View command. The results are a mesh overlay on every part participating in the simulation.

Generate Meshes | 33

NOTE If areas of the model need a finer or more coarse mesh, add local mesh controls. Local mesh controls are covered in another tutorial. Previous (page 32) | Next (page 34)

Run the Simulation We are now ready to run the simulation.

1 In the Solve panel, click Simulate displays.

. The Simulate dialog box

The dialog box more command >> exposes the messages section. If there are process steps to do, such as add constraints, the message is reported here. 2 Click Run. The simulation processes and returns results. Previous (page 33) | Next (page 35)


View and Interpret the Results

After the simulation completes, the graphics display presents the Von Mises Stress results plot. The complete set of results is posted in the Results folder. There are various commands for viewing result data. Most are located in the Result and Display panels.

1 In the Display panel, click Show Maximum Value . In the graphics window, a label with a leader points to the location of the maximum value. In this example, the maximum value is obscured by other components. 2 Expand the assembly browser node to view the list of components. 3 Turn off visibility of the parts hiding the stress location. ■ Lower Plate:1 ■

Upper Plate:1

Right-click each component, and click Visibility. 4 Rotate and Zoom as needed to view the location of the Maximum Value.

View and Interpret the Results | 35

Double-click the various results nodes to display the results in the graphics window. Previous (page 34) | Next (page 37)


Summary

The previous image is what you see if you look at the Displacement results for this simulation. Now that you have completed this tutorial, you have a basic understanding of the typical workflow in the stress analysis environment. This workflow includes: ■ Creating a simulation. ■

Excluding components not needed for the simulation.

■

Assigning materials as overrides of the existing material.

Summary | 37

■

Adding constraints and loads, sometimes called boundary conditions.

■

Adding contact conditions.

■

Generating meshes.

■

Running the simulation.

■

Viewing and interpreting the results.

What Next? As a next step, look into creating advanced contact conditions and local mesh controls. The Contacts and Mesh Refinement tutorial takes you into these topics. Previous (page 35)


Contacts and Mesh Refinement

3

About this tutorial

Use advanced and local mesh refinement to improve the stress results. Category

Simulation

39

Time Required

20 minutes

Tutorial File Used

Bracket_Assembly.iam

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. Two simulations are covered. The first one corresponds to a structural static study with separation contact and advanced meshing settings. The second one involves additional local mesh control. Objectives ■ Apply manual contacts. ■

Modify automatic contacts.

■

Add local mesh controls.

Prerequisites ■ Be familiar with the Stress Analysis environment, and complete the tutorial Assembly Stress Analysis. ■

Know how to use the model browser and set the active project.

■



Open the Model The first simulation walks, step by step, through the definition of a structural static FEA analysis. It includes the creation of manual contacts and selection of advanced meshing settings and concludes by viewing the results. 1 Check to see that project file is set to Tutorial_Files.ipj.

40 | Chapter 3 Contacts and Mesh Refinement

2 On the ribbon, click Get Started tab ➤ Launch panel ➤ Open . 3 Navigate to the Assembly FEA 2 folder, and then click Bracket_Assembly.iam. 4 Click Open. Previous (page 39) | Next (page 41)

Stress Analysis Environment Switch to the Stress Analysis environment. 1 Click the Environments tab.

2 Click the Stress Analysis

environment command.


Create a Simulation Create a simulation.

1 Click Create Simulation dialog box.

, to display the Create New Simulation

2 For the simulation Name, enter Separation Contact. 3 On the Simulation Type tab, specify Static Analysis. 4 Click OK. A new simulation named Separation Contact is created and appears in the browser. Previous (page 41) | Next (page 42)

Stress Analysis Environment | 41

Exclude Components For this simulation, the Sleeve component is not relevant, so we will exclude it. 1 In the browser, expand the model node to reveal the components of the assembly. 2 We want to evaluate the response to forces of the bolt when the Sleeve component is not present. We must exclude it from the simulation. Right-click the Sleeve component and select the Exclude From Simulation option. Alternatively, right-click the Sleeve component in the graphics region, and click the command.


Assign Materials The next step is to define the Materials. When a simulation is created, a Material folder is included in the simulation structure. This Material folder is populated whenever you specify override materials in place of the originally assigned material. 1 Double-click the Material folder. In the Assign Materials dialog box, a spreadsheet-type list containing all the parts and their materials displays.


2 In the Override Material column, click the cell corresponding with the Bolt component. 3 In the drop-down list, select Steel. 4 Right-click the cell, and click Copy. 5 For the following parts, multi-select the cells in the Override Material column, right-click, and click Paste. ■ Bracket ■

Mount

■

Washer

■

Nut

NOTE All occurrences of the Washer are updated at one time. 6 Click OK. Previous (page 42) | Next (page 43)

Add Constraints and Loads To define constraints and loads, use the commands available in the ribbon panels. Alternatively, right-click the browser node for the input type, and click the command there. 1 On the ribbon, click Stress Analysis tab ➤ Constraints panel

➤ Fixed. The dialog box displays with the Face selector active. 2 Choose the appropriate faces. Multiple faces can be selected. In this case, the faces represent a rigid attachment that occurs later in the manufacturing process.


3 Click OK to complete the constraint inputs. Add the second constraint:

1 Click the Fixed

command.

2 Select the cylindrical faces of the slot feature.


3 Click OK. Next, we add a force or load. These steps define a condition where the assembly receives a constant load in a given direction.

1 Click Stress Analysis tab ➤ Loads panel ➤ Force. The dialog box displays. 2 Choose the flat face at the bolt head. 3 Click the More command to expand the dialog box, and check Use Vector Components. 4 For the Fz component, enter 225. It defines the force magnitude and direction.


5 Click OK. We now have defined materials, structural load, and constraints. In the browser, expand the Constraints and Loads nodes for viewing. Click a node to highlight the selection or location in the graphics window; and double-click to edit the definition. Previous (page 42) | Next (page 46)

Define Contact Conditions You define contacts manually by selecting pairs of faces; these contacts are useful for cases in which the initial default contact tolerance is too small. Before manually adding contacts, use Automatic Contacts to detect the in-tolerance contact conditions.

1 In the Contacts panel, click Automatic . Contact conditions are automatically defined using the Contact defaults from the Stress Analysis Settings.


As you manually add contacts, you choose from various contact types such as Separation, Sliding / No Separation, and so on. We will now define manual contacts and set them to the Separation type. Additionally, we will modify two automatically created contacts to be the Separation type.

1 Click the Manual

command.

2 Set the Contact Type to Separation. 3 Select the faces for the new contacts as follows

a In the graphics region, click the Bolt cylindrical face as selection 1.

Define Contact Conditions | 47

b Move the cursor over the area where the Bolt component passes through the Bracket. When the cylindrical face on the Bracket highlights, click to select it. c Click Apply. d Reorient the model to do the same for the similar area near the Bolt head.

e Click the cylindrical face of the Bolt component.


f Move the cursor over the area where the Bolt component passes through the Bracket. When the cylindrical face on the Bracket highlights, click to select it. g Click OK. Now, we modify two automatic contacts to change them to the Separation contact type. 1 In the browser, expand the Contacts and then the Bonded folders. 2 Select contact Bonded:1, then hold down the Ctrl key and select contact Bonded:2. 3 Over one of the selected contacts, right-click and select Edit Contact. 4 Select Separation from the Contact Type drop-down list. It assigns the selected contact condition. 5 Click OK. With the contact conditions defined, we can move to specifying the mesh settings. Previous (page 43) | Next (page 50)

Define Contact Conditions | 49

Specify and Preview Meshes 1 In the Prepare panel, click Mesh Settings box displays.

. The settings dialog

2 Toward the bottom of the Common Settings section, click the check box for Create Curved Mesh Elements. 3 If Use part based measure for Assembly mesh is unchecked, check the option. This option is useful when you need a higher mesh resolution in smaller parts. It generally leads to larger number of elements for the overall assembly. 4 Click OK.


Before starting the simulation, we can view the mesh. In the Prepare panel,

click Mesh View . Alternatively, in the browser, right-click the Mesh folder to access the command. Previous (page 46) | Next (page 51)

Run the Simulation Now, we will run the simulation.

1 In the Solve panel, click the Simulate dialog box displays.

command. The Simulate

If there are any preprocess related messages, they are presented in the expanded section of the dialog box. Click the More command (>>) to expand the dialog box. 2 When ready, click Run, the Simulation progress displays in the dialog box. Wait for the simulation to finish. You can run more than one simulation at a time. Multi-select the simulation nodes in the browser, right-click, and click Simulate. The results are displayed within the Results folder of each simulation. Previous (page 50) | Next (page 51)

View and Interpret the Results After the simulation finishes, the Results folder is populated with the simulation results and the graphics region updates to display a results plot. 1 Expand the Results folder. By default, the Von Mises Stress plot displays.

Run the Simulation | 51

2 In the browser, the current result plot has a check mark by the node icon. To activate other plots, double-click the particular plot node you are interested in seeing. The display updates to present that plot. Now you can perform post-processing tasks. For example, viewing the results with smooth shading or contour plots.

1 In the Display panel, click Show Maximum Value


.

2 Using the view commands, reorient the model so you can see the maximum value area. 3 If the maximum value location is obscured by other components, you can hide those components. In the browser, right-click the components and click Visibility. Maximum values can be also shown in the Parametric Table for summary and comparison with other simulations. In this case, we will add a Design Constraint, maximum result value, for the assembly.

1 In the Manage panel, click Parametric Table . 2 In a table cell, right-click and click Add Design Constraint. The Select Design Constraint dialog box displays. 3 Click Von Mises Stress. 4 Click OK.


We have concluded the first simulation. The second simulation uses most of the items defined in this first simulation. The simulation study will be duplicated and modified as required for the additional study. Previous (page 51) | Next (page 54)

Copy and Modify Simulation The second simulation uses the same analysis as the first simulation. In addition, a local mesh refinement is defined to improve the stress results. We will create a copy of the first Simulation Study and edit the copy to define the second analysis. 1 Right-click the Simulation Study (Separation Contact) node at the top of the browser and click Copy Simulation. The new simulation is automatically activated. 2 Right-click the newly created Simulation Study browser node and click the Edit Simulation Properties. The properties dialog box displays. 3 Change the simulation Name to Local mesh refinement. 4 Click OK. Previous (page 51) | Next (page 54)

Specify Local Mesh Controls Next, we define the local mesh refinement. 1 Activate Mesh View and orient the model as shown. 2 Right-click the Mesh folder, and click Local Mesh Control. 3 Select the corner blend face, and enter 0.5 mm for the Element Size value.


4 Click OK. 5 To preview the mesh, right-click the Mesh folder and click Update Mesh.

Specify Local Mesh Controls | 55

The mesh preview shows a much finer mesh at the corner blend face compared to the mesh from the first simulation. Previous (page 54) | Next (page 56)

Run the Simulation Again After making the previous modifications, run the Simulate command using the right-click menu or the command from the ribbon.

1 In the Solve panel, click the Simulate dialog box displays.


command, the Simulate

2 Click Run. The Simulation progress is reported in the dialog box. 3 Click OK. Previous (page 54) | Next (page 57)

View and Interpret the Results Again Again, the Results folder is populated with the results. 1 Expand the Results node. By default, the Von Mises Stress plot displays.

2 In the Display panel, click Show Maximum Result to display the location of the maximum result. Hide components, as needed, to see the exact location.

View and Interpret the Results Again | 57

Maximum result values can be also shown in the Parametric Table for summary and comparison with other simulations. In this case, we will add a local constraint (maximum result value for a specific assembly component)

1 In the Manage panel, click the Parametric Table

command.

2 Right-click on a cell in the table, and click Add Design Constraint. 3 Click Von Mises Stress 4 Close the parametric table. To compare result values in the Parametric table, simply check the corresponding boxes in the other simulation studies. Previous (page 56) | Next (page 59)


Summary

In this tutorial, you created two simulations. In completing each simulation, you learned how to: ■ Copy an existing simulation to make new ones. ■

Define manual Contacts.

■

Modify automatic contacts.

■

Add local mesh controls.

■

Display design constraints in the parametric table.

■

Use multi-select to change component visibility.

■

Use Copy / Paste for material overrides.

What Next? As a next step, consider completing the following tutorials: ■ Part Modal and Stress Analysis ■

Assembly Modal Analysis

Previous (page 57)

Summary | 59

60

Assembly Modal Analysis

4

61

About this tutorial

Perform a structural frequency (modal analysis) study to find natural mode shapes and frequencies of vibration. Category

Simulation

Time Required

30 minutes

Tutorial Files Used

Suspension-Fork_Complete.iam

62 | Chapter 4 Assembly Modal Analysis

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. The tutorial uses an Inventor assembly. It demonstrates the process to create, solve and view results using 3D plots to illustrate the various mode shapes and corresponding frequency values. Manual contacts and selection of advanced meshing settings are included. The first 10 mode shapes are found and the results are explained. Objectives ■ Create a new modal simulation. ■

Use Manual Contacts to establish the correct relationship between components.

■

Exclude components, or use a Design View Representation to remove components from the simulation.

■

Override materials.

■

Add constraints.

■

Manually add contacts.

■

Specify mesh parameters.

■

Run the simulation.

■

View the results.

Prerequisites ■ Complete the Assembly Stress Analysis & Contacts and Mesh Refinement tutorials. ■



About this tutorial | 63

Open the Assembly

1 Check to see that the project file is set to Tutorial_Files.ipj. 2 Click the Open command, and navigate to the Assembly FEA 3 folder. 3 Click on Suspension-Fork_Complete.iam, and click Open. Alternatively, double-click the .iam file. 4 Use Save As to save the model to a new name, such as Suspension-Fork_Stress.iam. It is not necessary to say Yes to all components. 5 In the model browser, expand the Representations folder and then the Level of Detail folder. 6 Double-click the All Parts Suppressed level of detail representation.


7 In the browser, right-click and clear the check mark next to Suppress for the following components: ■ Fork-Crown:1 ■

Fork-Slider:1

■

Fork-Tube:1

■

Fork-Slider_MIR:1

■

Fork-Tube_MIR:1

8 Right-click the Level of Detail folder node, and click New Level of Detail. 9 Rename the new representation to Stress LOD. 10 Save the assembly model. We made this level of detail representation to take advantage of the stress analysis environments use of representations. Previous (page 62) | Next (page 65)

Create a Simulation Study To create a simulation you must switch to the Stress Analysis Environment, then you can begin to define the simulation. 1 On the ribbon, click Environments tab ➤ Begin panel ➤ Stress

Analysis. This action takes you into the stress analysis environment.

2 Click on the Create Simulation Simulation dialog box displays.

command. The Create New

3 For the Simulation Name, specify Mode Shapes. 4 Leave the Design Objective set to Single Point. 5 For Simulation Type, select Modal Analysis. 6 Enter 10 for the number of modes. 7 Check the Enhanced Accuracy option. The remaining parameters use default settings.

Create a Simulation Study | 65

8 On the Model State tab, for Level of Detail, select Stress LOD. Note that it may already be active. 9 Click OK. A new Simulation Study is created and populates the browser with simulation-related folders. Previous (page 64) | Next (page 66)

Exclude Components In any assembly, there can be components and part features that are not affected by the forces acting on the assembly or have no bearing on the outcome of applying the forces. For these reasons, and to help the simulation solve faster, it is good to exclude those parts when simulating an assembly response. For a single part simulation, you consider suppressing specific model features. For an assembly analysis, you use the component context menu option Exclude From Simulation. Exclusion is different from suppression, which is what is done when you use a Level of Detail representation. If you think you plan to use the component at a later date in the same simulation, then use the Exclude From Simulation. If you know you will not refer to it later, then you can use a Level of Detail representation. Because we purposely defined an Assembly Level of Detail representation for this stress analysis simulation, we do not need to exclude several parts. We simply specify that the simulation will use that representation. NOTE In most cases, this is the optimum way to lower the component count. If you do not specify the Level of detail representation when first creating the simulation, then you can use the following steps to make use of it. 1 Right-click the Simulation browser node, and click Edit Simulation Properties. 2 Click the dialog box Model State tab. 3 For Level of Detail input, click the drop-down list and select Stress LOD. 4 Click OK. The assembly updates to represent the requested level of detail. This workflow illustrates how advanced planning, wherever possible, can reduce the effort needed in other phases of your design project.



Assign Materials Next, you define the component materials. Not all Autodesk Inventor materials are suited to analysis, so it is necessary to define materials completely in advance, or select from the materials that are defined. If you want to modify materials, use the Materials and Appearances tools. Modifying materials is not part of this tutorial. 1 On the ribbon, click Stress Analysis tab ➤ Material panel ➤ Assign

. The dialog box displays. 2 In the Override Materials column, click the cell for the first component. It activates the materials list within the cell. 3 Click the down arrow to display the drop-down list, and click Titanium. 4 Right-click the cell, and select Copy. 5 Multi-select the other component cells of the Override Material column, right-click, and select Paste. 6 Click OK to accept the changes and close the dialog box. The Material browser node is populated with a material node containing a node for each component assigned that material override. Previous (page 66) | Next (page 67)

Add Constraints Using constraints, we specify the boundary conditions for this simulation. 1 In the Constraints panel, click Fixed Constraint. The dialog box displays with the Selector command active and ready for use. 2 Choose the Fork-Crown face as shown in the following image.


3 Click OK. Previous (page 67) | Next (page 68)

Create Manual Contacts To define contacts, we must do two things. First, we must have the software automatically detect contacts that meet the default criteria found in the Stress Analysis Settings. Second, we must manually define additional contacts. Manual contacts, consisting of pairs of faces, are used for cases in which the initial default contact tolerance is too small. The default contact type is bonded; however, you can also assign various contact types such as Separation, Sliding/no Separation, and so on. In this example, we add a manual bonded contact to model the relative displacement of the fork elements. 1 In the Contacts panel, click Manual Contacts.


Since you have not already run an automatic detection of contacts, you will receive a message that automatic detection will be run before manual contacts can be added. 2 Click OK. Automatic contacts detect contacts within the default tolerance. Qualified contacts populate the Contacts folder. Once automatic contacts have been established, the Manual Contacts dialog box displays. To see the automatically created contacts, expand the Contacts folder in the browser. 3 When the Manual Contacts dialog box appears, select the outer surface of Fork-Tube.ipt and the main interior surface of the Fork-Slider.ipt components. The contact type should be Bonded. Click Apply. 4 Check to see if a contact was made between the Fork-Tube_MIR.ipt and the main interior surface of the Fork-Slider_MIR.ipt components. The contact type should be Bonded. If not, create the contact with these components using the method from step 3. 5 One more manual contact must be added to represent the component to which the Fork-Sliders are bolted. Select the two opposing faces of the Fork-Slider as shown in the following image. View navigation commands are available to orient the view.

6 Ensure the contact type is Bonded. 7 Click OK. A bonded contact is assigned between the two faces as seen in the image. Next, we specify the meshing options. Previous (page 67) | Next (page 70)

Create Manual Contacts | 69

Specify Mesh Options Use the advanced meshing settings to create a mesh that considers this type of curved and long geometry. 1 In the Prepare panel, click Mesh Settings. 2 In the dialog box: ■ Set Average Element Size to 0.05. ■

Check Create Curved Mesh Elements. Use this option to better mesh round areas of the geometry.

■

Ensure that Use part based measure for assembly mesh is checked. This option creates a higher mesh resolution in smaller parts; it usually generates more elements for the overall assembly.


Preview Mesh and Run Simulation Before starting the simulation, we can view the mesh. 1 In the Prepare panel, click Mesh View. Alternatively, you can right-click the Mesh browser folder and select the command. The command is a display state command and acts like an on/off switch for the mesh display. Notice that in the upper corner of the graphics window the node and element counts are presented.


2 In the Solve panel, click the Simulate command and a dialog box displays. 3 Click Run, the Simulation progress displays in the dialog box. Previous (page 70) | Next (page 71)

View and Interpret Results After the simulation finishes, the graphics window displays the first mode, and the Results browser folder populates with all the simulation results.

View and Interpret Results | 71

1 Expand the Results folder. 2 Expand the Modal Frequency folder to expose the list of available Mode Shapes corresponding to each calculated natural frequency. Double-click the frequency of choice to display it. The color bar shows relative displacement values. The units are not applicable since the mode shapes values are relative (They have no actual physical value at this point) Now you can perform post-processing tasks using the Display panel commands. These commands are described in Help. Animate the results 1 In the browser, select a mode shape you want like to see animated. 2 Click the Animate Results command on the Result panel. 3 Specify 10 for the number of steps. Steps are analogous to images for playback. 4 In the dialog box, click the Play command.


5 When finished observing the displacement animation, click OK to exit the animation playback. The Animate Results dialog box also has options for displaying the original wireframe with the plot. You can also record the animation to present or retain for records. Previous (page 70) | Next (page 73)

Summary

In this tutorial you performed a structural frequency (modal analysis) analysis with the goal of finding natural mode shapes and frequencies of vibration. The steps performed included: ■ Create a modal simulation. ■

Use Manual Contacts to establish the correct relationship between components.

■

Exclude components, or use a Design View Representation to remove components from the simulation.

■

Override materials

■

Add constraints

■

Manually add contacts

■

Specify mesh parameters

■

Run the simulation

■

View the results

Summary | 73

What Next? As a next step, visit http://www.autodesk.com and try some of the Skill Builders for Stress Analysis. Try using some of these learned techniques on your models. Previous (page 71)


FEA Assembly Optimization

5

75

About this tutorial

Optimize an assembly model using the parametric variations provided in Stress Analysis. Category

Simulation

Time Required

30 minutes

Tutorial Files Used

Robot Base.iam

76 | Chapter 5 FEA Assembly Optimization

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. Objectives Minimize the mass of the structure while keeping displacement and stress within allowable values. Consider safety criteria and profile size changes. Prerequisites ■ Complete the Part Modal and Stress Analysis tutorial. ■

Familiarize yourself with the ribbon user interface.


Open the Assembly 1 Click

➤ Open.

2 Set the Project File to Tutorial_Files.ipj. 3 Open Assembly Optimization using FEA ➤ Robot Base.iam. 4 On the ribbon, click Environments tab ➤ Begin panel ➤ Stress

Analysis

.


Define the Simulation 1 On the ribbon, Manage panel, click Create Simulation

.

Open the Assembly | 77

2 In the Create New Simulation dialog box, enter the following: ■ Name: Optimization ■

Design Objective: Parametric Dimension

■

Simulation Type: Static Analysis

3 Click OK. A new simulation is created and the browser is populated with folders. Previous (page 77) | Next (page 78)

Assign Materials 1 On the ribbon bar, Material panel, click Assign Materials

.

2 For the base_plate:1 component, click the Override Material drop-down list and select Steel. Notice that the Safety Factor column shows that Yield Strength is used for safety analysis. 3 Right-click the Override Material cell for base_plate:1 and select Copy. Multi-select the other Override Material cells, right-click, and select Paste. Multiple instances of a component change with one paste. Click OK to close the dialog box. Previous (page 77) | Next (page 78)

Adding Constraints Add constraints to denote mechanical and environmental conditions.

1 On the ribbon bar, Constraints panel, click Fixed

.

2 Rotate the model and select the faces that would contact the floor surface.



Adding Loads Define the load where the robot mounts to the base. The mounting plate on the robot is round, and the base plate is square. To apply the force in the area where the robot mounts, we must split the base plate face. (This step has already been performed for you.)

1 On the ribbon bar, Loads panel, click Force

.

2 Move the cursor over the center of the base plate component to highlight the round face. Click to select the face.

Adding Loads | 79

3 In the Force dialog box, for Magnitude, enter 2000 and click OK. A yellow (default color) glyph denoting the force direction is positioned at the center of the face. Previous (page 78) | Next (page 80)

Modify the Mesh Review the mesh settings and make a minor adjustment.

1 On the ribbon bar, Prepare panel, click Mesh Settings

.

2 In the Mesh Settings dialog box, click Create Curved Mesh Elements. This option creates elements that follow geometry curvature. 3 The Use part based measure for Assembly mesh option is checked by default, which is correct for this simulation. This option produces a higher mesh resolution in smaller parts, with a resulting increase in mesh elements overall. 4 Click OK to apply the change and close the dialog box. Previous (page 79) | Next (page 81)


Preview the Mesh Previewing the mesh is an optional step. Perform the mesh preview to examine the mesh in areas where features are smaller, or where transitions occur, to ensure an adequate mesh results.

On the ribbon bar, Prepare panel, click Mesh View

.


Preview the Mesh | 81

Create Parametric Geometry Produce a range of geometric configurations, involving the width of the model components, to facilitate weight optimization. First, expose model parameters for use as simulation parameters. 1 In the Simulation browser, expand the Robot Base.iam node to expose the components in the assembly. Right-click base_plate:1 and click Show Parameters. 2 In the Select Parameters dialog box, select the check box next to the MemberWidth parameter to include the parameter in the parametric table.

3 Click OK. Define the parameter range.

1 On the ribbon bar, Manage panel, click Parametric Table

.

2 In the Parameters section, base_plate.ipt row, for the MemberWidth parameter, enter 1-2 in the Values cell. Press Enter to update the row contents.


Once the parameter is defined, generate the parametric configurations. 1 In the Parameters section, right-click the MemberWidth row and select Generate All Configurations. 2 After the configurations are generated, you can view them using the Current Value slider.

Create Parametric Geometry | 83


Optimization Criteria As mentioned at the outset, the goal is to minimize the mass using the range of geometric configurations and safety factor criteria. The Design Constraints section of the Parametric Table enables access to the results criteria. To add the first design constraint: 1 If the Parametric Table is not displayed, in the Manage panel, click Parametric Table. 2 In the Design Constraints section, right-click the row and select Add Design Constraint. 3 In the Results Component section of the Select Design Constraint dialog box, select Von Mises Stress. Geometry Selections is set to All Geometry. Click OK. The result component is listed as a design constraint. 4 In the Max Von Mises Stress row, click the Constraint Type cell to access the drop-down list. In the drop-down list select Upper limit. 5 In the Limit cell, enter 4.5e+004. 6 In the Safety Factor cell, enter 1.5. Add Displacement as a design constraint. 1 Right-click a row and click Add Design Constraint. 2 In the Select Design Constraint dialog box, select Displacement. All Geometry is the default. Click OK. 3 In the Constraint Type cell, select Upper limit. 4 In the Limit cell, enter 0.01. Add Mass as a design constraint. 1 Right-click a row and click Add Design Constraint. 2 In the Select Design Constraint dialog box, select Mass and click OK. For the Mass design constraint, leave the constraint type as View the value. The Design Constraints section of the Parametric Table should look like the following image:


Close the table. Previous (page 82) | Next (page 85)

Run the Simulation 1 On the ribbon bar, Solve panel, click Simulate

.

2 In the Simulate dialog box, ensure that the simulation will run using the Smart set of configurations. 3 Click Run. Previous (page 84) | Next (page 85)

View and Interpret the Results The Simulation browser Results node is populated with the simulation results. However, we use the Parametric Table and the visualization capabilities to assess the design and optimize for mass. 1 On the ribbon bar, Manage panel, click Parametric Table. 2 In the Parametric Table, note the presence of a green circle in two Result Value cells. A green circle indicates that the Result Value is within the associated safety factors.


3 Change the Mass Constraint Type to Minimize. The parametric values change to show the configuration with the least mass that meets the given constraints. In this case, the original profile width value was 2 inches. The optimized configuration is 1.5 inches, which reduces the mass.

NOTE If you move the slider to show a current value of 1.0, the table updates and you see that maximum displacement exceeds the safety factor criteria. A red square, next to the Result Value, denotes the condition. Previous (page 85) | Next (page 87)


View and animate 3D plots View 3D and XY plots to understand the behavior of the model under the defined boundary conditions. After running a simulation, you can perform post-processing tasks using the assorted commands in the Display panel. You can choose shading options, display minimum and maximum labels, insert probes, and so on. The Results node, in the Simulation browser, is populated with the simulation results based on the criteria you specified. The Von Mises Stress result (default) is displayed as a 3D color plot. In this example, because of the connections between profile geometry, stress concentrations are expected at the joints. To see the stress distribution farther away from the concentrations, change the Color Bar settings.

1 On the ribbon bar, Display panel, click Color Bar. 2 In the dialog box, uncheck Maximum. 3 Enter 5 in the edit field above the check box. Click Apply. 4 Use the view commands to rotate the model so you can see the underside of the assembly. Note how the stress is distributed in the members.

View and animate 3D plots | 87

To view other results such as Displacement, double-click the appropriate browser node to update the display.

For simulations involving parametric dimensions, move the slider to various parameter values to display the associated results. Previous (page 85) | Next (page 88)

View XY Plots XY plots show a result component over the range of a parameter. To view an XY plot, right-click the parameter row and select XY Plot.


The XY plot displays the Displacement results versus the parametric configurations. Hover the cursor over a plot point to display the displacement value at that point.

View XY Plots | 89


Summary In this tutorial, you learned to: ■ Create a simulation. ■

Specify materials, constraints, and forces.

■

Specify parametric dimensions and generate configurations.

■

View different configurations as 3D color plots and XY plots.

What Next?


If you have not completed the other FEA tutorials, why not do so now? Or, if you have not used Dynamic Simulation, work through those tutorials and learn how to use that simulation output in the Stress Analysis environment. Consider how this process applies to the products you design and manufacture. Previous (page 88)

Summary | 91

92

Stress Analysis Contacts

6

About this tutorial Use contacts to simulate interactions between assembly components in Inventor Stress Analysis. Category

Simulation

Time Required

45 minutes

Tutorial Files Used

Caulk Gun.iam

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. Prerequisites Perform some of the other Stress Analysis tutorials to become familiar with the Stress Analysis environment.. Navigation Tips ■ Use Next or Previous at the bottom-left to advance to the next page or return to the previous one. Next (page 94)

93

Overview In the structural analysis of an assembly involving multiple parts, you create contacts to define the relationship between the parts. Contacts transfer load between parts while preventing parts from penetrating each other. Contacts can simulate interaction between bodies that separate or come into contact during loading. Without contacts, parts do not interact with each other in the simulation. There are several different contact types you can use to simulate the physical behavior of an assembly. This tutorial presents an assembly modeled with many of the types of contact available in Inventor Stress Analysis. The contacts have already been created, either automatically or manually, in the model. Previous (page 93) | Next (page 94)

Open the Assembly A model of a caulk gun illustrates different contact types and how to use them in a static, structural analysis.

1 Click

➤ Open.

2 Set the Project File to Tutorial_Files.ipj. 3 Open Stress Analysis Contacts ➤ Caulk Gun.iam.

94 | Chapter 6 Stress Analysis Contacts



How a Caulk Gun Works We considered the following mechanics of the caulk gun when creating the simulation.


How a Caulk Gun Works | 97

1 User holds the handle [1] and pulls back on the trigger [2]. 2 The pin end of the trigger [3] pushes the actuator [4] forward. 3 The actuator tightly engages the plunger [5] and pushes it forward. 4 The plunger head [6] pushes the caulk tube bottom. 5 The tube is held in place by a ring [7] at the end of the caulk gun. Previous (page 94) | Next (page 99)


Assembly Simulation The caulk gun is an assembly which consists of several parts, some of which can move. Several operational scenarios can exist for the caulk gun, but we chose to simulate the assembly in a static equilibrium state. This simulation investigates when the trigger is pulled and the pushing force on the bottom of the caulk tube is about to overcome the internal tube resistance. At this instant, just before caulk exits the tube, the assembly is in static equilibrium. On the ribbon, click Environments tab ➤ Begin panel ➤ Stress

Analysis

to enter the Stress Analysis environment.

Expand Caulk Gun.iam in the Stress Analysis browser. We exclude the following components from the simulation: ■ Caulk Tube [8] ■

Actuator Spring [9] (not modeled, but simulated with Spring contact)

■

Lock Spring [10]

■

Lock [11]

Assembly Simulation | 99


Contact Types Inventor Stress Analysis provides the following Contact types: ■ Bonded ■

Separation

■

Sliding / No Separation

■

Separation / No Sliding

■

Shrink Fit / Sliding

■

Shrink Fit / No Sliding


■

Spring

In the Stress Analysis browser, expand the Contacts node to view the contact types currently in use for the caulk gun simulation. As you create or edit contacts, they are added under existing contact type nodes or to newly created nodes.

Contact Types | 101

In the browser, right-click a contact and select Edit Contact. The Edit Automatic Contact or Edit Manual Contact dialog box displays and shows the available contact types:


Bonded Contact The Bonded contact simulates rigid bonding of faces to each other. Typical Bonded contacts include weld or glue joints between two parts. In the model, the Front Frame-Main Frame and the Front Frame-Handle interfaces are weld joints, as shown in the following image. You use Bonded contacts to simulate these joints in the simulation.



Separation Contact The Separation contact allows separation between parts but prohibits part penetration. In the model, the pin end of the trigger contacts the actuator. When you pull the trigger, the pin end of the trigger pushes the actuator forward. When the trigger is released, the pin end and the actuator can separate. Since the pin end cannot penetrate the actuator and separation can occur between the parts, the contact relationship is simulated with the Separation contact.

Separation Contact | 103


Sliding and No Separation Contact The Sliding/No Separation contact allows relative sliding between contact faces, but prohibits separation.


Sliding/No Separation can occur between planar faces like the Trigger-Handle interface.

Sliding and No Separation Contact | 105

It can also occur between circular faces such as the Pin-Handle and Pin-Trigger interfaces.



Separation and No Sliding Contact The Separation/No Sliding contact allows contact faces to separate, but prohibits relative sliding when they touch. For the Actuator-Plunger interface, the Separation/No Sliding contact is appropriate. When the trigger is pulled, the actuator is pushed forward. This results in separation between the top surface of the plunger and the actuator. At the same time, engagement occurs between the bottom surface of the plunger and the actuator. It is reasonable to assume that the engagement/separation occurs without slippage between the actuator and plunger. In the following image, note that the surfaces of the plunger and actuator are split into multiple faces. In this manner, the contact surfaces are more explicitly defined.

Separation and No Sliding Contact | 107


Shrink Fit and No Sliding Contact The Shrink Fit/No Sliding contact simulates conditions like Separation/No Sliding with the parts in an initial state of interference.


The model has a ring that tightly fits the front frame and prevents the caulk tube from exiting the caulk gun when the plunger moves forward. The front face of the ring registers against the front frame without penetration. Therefore, this interface is simulated with the Separation contact. The outer diameter of the ring has an interference fit with the front frame. The ring is press fit into the frame so that it remains in position without a caulk gun in place. This press fit allows the operator to push the ring out easily and replace it with a different size, as appropriate. The outer diameter of the ring and the front frame can separate without sliding. Since they are initially in a state of interference, the Shrink Fit/No Sliding contact is appropriate.

Shrink Fit and No Sliding Contact | 109


Spring Contact The Spring contact simulates conditions of a spring between two faces. In the model, the actuator spring is simulated using a Spring contact. The use of the Spring contact eliminates complexities associated with modeling the physical spring part.



Loads and Constraints With the contacts defined, proceed further with the model analysis. To use the caulk gun, you hold the handle and pull the trigger. From the static analysis point of view, the components are under force and deform before the plunger head moves the bottom of the tube. We can reasonably assume that the components deform relative to the main frame. As such, we can apply a: ■ Fixed constraint on the main frame edge [12] ■

Force on the handle [13]

■

Force on the trigger [14]

■

Force on the plunger head [15]

■

Force on the ring [16]

Loads and Constraints | 111

The tube is held in place by the front frame, ring, and plunger head. When the force from plunger head is large enough, the bottom of the tube moves further into the tube and pushes caulk out of the nozzle. For the static analysis, we simulate the instant at which the force on the tube bottom is in equilibrium with the tube resistance. Before the tube bottom moving, we examine the stress and deformation of the whole structure and components. Previous (page 110) | Next (page 112)

Simulation Results 1 On the Stress Analysis tab, Solve panel, click Simulate

.

2 On the Simulate dialog box, click Run to begin the simulation. The Simulate dialog box remains open, displaying the progress bar, until the computation is complete.


When the simulation finishes, a deformation plot of the model is shown in the graphics window. The Von Mises Stress results are also displayed using the default color bar settings. On the Display panel, click Maximum Value

to view the maximum stress and its location.

The maximum Von Mises Stress of approximately 291 MPa occurs on the Pin. To view the location of maximum stress, turn off the visibility of all parts except the Pin.

Simulation Results | 113

As this stress is greater than the Pin material (steel) yield strength of 207 MPa, the analysis indicates the Pin will yield. To meet strength criteria, you modify the design or change the Pin material. NOTE In this tutorial, the model is intended to illustrate the contact types and their application. Some contact areas such as the Plunger-Actuator interface are small. Take care when providing spring stiffness and force values as the displacement and stress results are sensitive to parameter values. Also note that some parts may have areas of large deformation, which are better suited to a nonlinear analysis. Previous (page 111) | Next (page 114)

Summary In this tutorial, you learned about Inventor Stress Analysis contacts and how they simulate interactions between assembly components. What Next? To investigate design workflows further using Inventor Stress Analysis, refer to other Help documents and tutorials included with Inventor.


Previous (page 112)

Summary | 115

116

7

Frame Analysis

About this tutorial

Perform basic structural analysis of your frame structures with respect to deformations and stresses. Category

Simulation

Time Required

30 minutes

117

Tutorial File Used

analyze_frame.iam

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. The Frame Analysis environment is a special environment within assembly and weldment files. The environment has commands unique to its purpose. You can access the tools from the Design or Environments tabs. When you open a Frame Analysis and set up your simulation, the assembly frame model is automatically converted to a simplified model of nodes and beams. The graphics window displays beams, nodes, and the gravity glyph. Then, you define the boundary conditions (consisting of loads and constraints). You can also change beam materials, and specify connections (releases and rigid links). Once these inputs are entered, you can run the simulation and view the behavior relative to the conditions you defined. Objectives ■ Create a simulation. ■

Evaluate and assign materials.

■

Evaluate and assign beam properties.

■

Add loads.

■

Add constraints.

■

Run a simulation.

■

View the results.

Prerequisites ■ Know how to use the Quick Access toolbar, tabs, and panels on the ribbon, model browser, and context menus. ■

Know how to navigate the model space with the various view tools.

■


■

Complete the Frame Generator tutorial.

■

See the Help topics for further information.

118 | Chapter 7 Frame Analysis


Open the Assembly To begin, open the assembly to analyze. 1 Click the Open


2 Set the Project File to tutorial_files.ipj 3 Select Frame Analysis 1 ➤ analyze_frame.iam. 4 Click Open. 5 Click Save as to save the file with a different name, such as: analyze_frame_tutorial.iam. Previous (page 117) | Next (page 119)

Frame Analysis Environment We are ready to enter the Frame Analysis environment. 1 On the ribbon, click Environments tab ➤ Begin panel ➤ Frame

Analysis

.

Initially, there are only three commands enabled: Create Simulation, Frame Analysis Settings, and Finish Frame Analysis. For now, create a simulation and review the settings in the next step.

2 On the Manage panel, click the Create Simulation The Create New Simulation dialog box opens.

command.

You can use the dialog box settings to specify a unique name, simulation type, and other simulation parameters.


There are two types of Frame Analysis. ■

Static Analysis evaluates structural loading conditions.

■

Modal Analysis evaluates natural frequency modes.

NOTE On the Model State tab, you specify the Design View, Positional, and Level of Detail to use for the simulation. Also, you can specify the iAssembly member to be associated with the simulation. The settings can be different for each simulation. 3 Click OK to accept the default settings for this simulation. The Inventor model is automatically converted into idealized nodes and beams, and a simulation is created. A gravity symbol also displays.


Frame Analysis Environment | 121

The browser populates with a hierarchical structure of the assembly and analysis-related folders. Most of the commands in the ribbon panels are now enabled for use. Disabled commands enable after you run the simulation. Previous (page 119) | Next (page 122)

Frame Analysis Settings Frame Analysis settings apply to all new simulations. Whenever a new frame simulation is started, these preferences are used. In the Frame Analysis Settings dialog box, you can specify: ■ If Heads up Display is the preferred method used during input and edit. ■

Colors for displayed boundary conditions, nodes, rigid links, gravity.

■

Scale for displayed nodes, loads, and constraints.

■

Default visibility settings for all components (beams and other parts) after the conversion.

■

Solver method used for beam releases.

■

Display of diagrams.

In this tutorial, we use the dialog boxes for input of boundary conditions values.

On the ribbon, click Frame Analysis Settings

in the Settings panel.

In the General tab, clear the Use HUD in Application check box. Click OK. Previous (page 119) | Next (page 122)

Assign Materials The next step is to look at the model materials and adjust the material. For this simulation, we only make a minor material change using materials that are fully defined.


Before you perform simulations, ensure that your material definitions are complete for those materials being analyzed. When a material is not completely or inadequately defined, a warning message displays in the Status folder in the browser. You cannot run a simulation until you change the material. NOTE You cannot edit a material if the project setting Use Styles Library is set to Read-Only. To change the setting requires exiting the tutorial. In this tutorial, we use a material that is already fully defined. You can modify the other materials at a later time. 1 In the browser, expand the Beams folder, and select Beam:1. Right-click and select Beam Materials. In the Beam Material dialog box, select the beam (DIN U 200 00000001.ipt) in the Beams area. NOTE Beam Material dialog box is also accessible when you click Material

on the Beams panel in the ribbon. 2 Check the Customize box. NOTE The Customize check box is only available when the parent beam is selected. 3 In the drop-down menu in the Material area, select Stainless Steel, Austenitic. 4 Click OK to exit the Beam Material dialog box. The browser Materials folder receives a Stainless Steel, Austenitic - DIN U 200 00000001.ipt folder added with all the components referencing that material listed within that folder. If you delete individual components from the folder, their material reverts to the assembly assigned material. Previous (page 122) | Next (page 124)


Change Beam Properties You can also change beam properties.

1 In the Beams panel, click the Properties command. The dialog box displays the list of beams, and basic and mechanical properties of a selected frame member. 2 To change the data, select the parent beam in the Beams area. 3 Check the Customize box to make the edits. In this tutorial, we do not customize any data. 4 Click Cancel to exit the Beam Properties dialog box. Previous (page 122) | Next (page 124)

Change Direction of Gravity When a frame analysis is created, gravity is automatically applied. In this tutorial, we change its direction. 1 In the browser, expand the Loads folder. Select Gravity and select Edit.

. Right-click,

2 In the Gravity dialog box, select Z Direction from the drop-down list. 3 Click OK to close the Gravity dialog box.



Add Constraints Next, we define the boundary conditions by adding structural constraints and loads. We start with constraints first. NOTE Constraints are required for frame simulations. If you start a simulation without constraints, a dialog box displays the error message: No constraints defined.

1 In the Constraints panel, click Pinned displays with the Origin selector active.

. The dialog box

2 Select the beam as shown in the image. The preview of the pinned constraint displays.

Add Constraints | 125

3 Make sure the Absolute option is selected in the Pinned Constraint dialog box. We insert the offset value using the absolute values measured from the beginning of the beam.


NOTE You can use the Local Systems command in the Display panel to show the beam coordinate systems to define the beginning of the beams. 4 In the Pinned Constraint dialog box, set Offset to 170 mm, and click OK. The Pinned constraint is applied. 5 Insert the second pinned constraint to the same beam. Again, click

Pinned

in the Constraints panel.

6 Select the same beam, and set Offset to 2330 mm. Click OK.


Add Constraints | 127

Add Constraints to the Next Beam We must insert pinned constraints to the opposite side of the cart. 1 In the browser, select Constraints folder. Right-click and select Pinned Constraint

.

2 Select the beam as shown in the following image. The preview of the pinned constraint displays.


3 In the Pinned Constraint dialog box, set Offset to 170 mm, and click OK. Pinned constraint is applied. 4 Insert the second pinned constraint to the same beam. In the browser, select Constraints folder. Right-click and select Pinned Constraint . 5 Select the same beam, and set Offset to 2330 mm. Click OK.

We applied all necessary constraints so we can add loads now. Previous (page 125) | Next (page 129)

Add Loads Now assign loads on the components.

1 In the Loads panel, click Force the Origin selector active.

. The dialog box displays with

Add Loads | 129

2 Select the middle beam where the force is acting.

3 In the dialog box, enter 500 N for the Magnitude value, and 0 degrees for Angle of Plane. NOTE The Angle of plane specifies the rotation of the XY plane where the force is acting. Angle in plane defines the angle of the applied force from the Z-axis. 4 Click the More button to expand the dialog box to display additional controls for specifying the force vector. In the Offset area, check the Relative box. You can now position the force to the middle of the selected beam. Enter 0.5 in the Offset edit field in the upper part of the


dialog box. Click OK to exit the Force dialog box.



In the Solve panel, click Simulate showing the status of the simulation.

. The progress bar displays



View and Interpret Results

After the simulation completes, the graphics window displays the Displacement results plot, by default. Expand the Results folder to explore the complete set of results. There are various commands for viewing result data. Most are located in the Result and Display panels. Save the assembly. You use this assembly in the Frame Analysis Results and Modal Type of Frame Analysis tutorials. Previous (page 131) | Next (page 133)


Summary

The previous image is what you see if you look at the Fx Forces results for this simulation. Now you have a basic understanding of the typical workflow in the frame analysis environment. This workflow includes: ■ Creating a simulation. ■

Assigning materials as overrides of the existing material.

■

Adding constraints and loads, sometimes called boundary conditions.

■

Running a simulation.

■

Viewing the results.

What Next? As a next step, explore the tools available for viewing and interpreting results. The Frame Analysis Results tutorial takes you through these topics.

Summary | 133

Previous (page 132)


Frame Analysis Results

8

About this tutorial

Category

Simulation

Time Required

15 minutes

Tutorial File Used

analyze_frame_tutorial.iam

135

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. Objectives ■ Open a simulation. ■


■

Display and edit diagrams.

■

View beam detail.

■

Adjust displacement display.

■

Display maximal and minimal values in the graphics window.

■

Animate results.

■

Generate report.

Prerequisites ■ Complete the Frame Analysis tutorial. ■

Know how to use the Quick Access toolbar, tabs and panels on the ribbon, model browser, and context menus.

■


■



Get Started To begin, open the assembly to analyze. 1 Click the Open


2 Set the Project File to tutorial_files.ipj 3 Select Frame Analysis 1 ➤ analyze_frame_tutorial.iam.

136 | Chapter 8 Frame Analysis Results

NOTE This assembly was created during Frame Analysis tutorial. 4 Click Open. Previous (page 135) | Next (page 137)

Frame Analysis Environment We are ready to enter the Frame Analysis environment. On the ribbon, click Environments tab ➤ Begin panel ➤ Frame Analysis

. We created a simulation during the Frame Analysis tutorial so the model with simulation results displays. The displacement results plot displays in the graphics window by default.


The browser populates with a hierarchical structure of the assembly and analysis-related folders. All the commands in the ribbon panels are now enabled for use. We can use the commands for viewing and interpreting results. Previous (page 136) | Next (page 139)


View and Interpret the Results

In the browser, expand the Results folder. The Results folder includes results for Displacement, Forces, Moments, Normal Stresses, Shear Stresses, Torsional Stresses, and the Diagrams folder. Expand a folder and double-click to display the particular result. When there are any errors or warnings during a simulation, they display in the Status folder. Our simulation ran without any problems, so the Status folder is empty. We now explore various tools located in the Result and Display panels for viewing result data. Previous (page 137) | Next (page 140)


Display Maximum and Minimum Values Minimum and maximum values quickly show the locations of load extremes.

In the Display panel, click Max Value . In the graphics window, a label with a leader points to the location of the maximum value.

In the Display panel, click Min Value . In the graphics window, a label with a leader points to the location of the minimum value. NOTE You can drag the labels to different locations. The following image shows maximum and minimum values for the Displacement results plot.


Cancel the selection of the Max Value and Mix Value options in the Display panel to hide the values. Previous (page 139) | Next (page 141)

View Beam Detail You can display detailed results for the selected beams. In the Result panel,

click Beam Detail

.

First, select a beam whose results you want to display. Select a beam as shown in the following image.

View Beam Detail | 141

In the Diagram Selection area, select the result data you want to display as a diagram. Select a particular force, moment, or stress to display its diagram, Fz for example. The displayed diagram is for viewing only and cannot be edited. A complete list of beam results displays on the right side of the dialog box. Click OK to close the dialog box. Previous (page 140) | Next (page 142)

Display and Edit Diagrams To display results for a given beam, you can add user-defined diagrams to the

graphics window. In the Result panel, click Diagram


.

In the Beams area, select how you want to specify which beams are included in the diagrams. In this tutorial, check the Selected Beams box, and select the beam as shown in the following image.

Now, select which results you want to display. Check the Fx and Fy boxes in the Loads area.

Display and Edit Diagrams | 143

Click OK to close the Diagram dialog box. You can adjust the display of beam diagrams in the Diagram Scales dialog box. In the browser, select Diagrams, right-click, and select Diagram Scales . Use the Expand, Contract, and Normalize buttons to adjust the scale of diagrams. Click OK to see the change in the scale in displayed diagrams. Previous (page 141) | Next (page 144)

Adjust Displacement Display You can scale the model deformation using the options in the Adjust Displacement Display drop-down list in the Display panel. Expand the Results folder, and double-click the Displacement browser node.


Select a multiple to improve the view of the deformation of the model. In the following image, the Adjusted x0.5 option is selected.

In the following image, the Adjusted x5 option is selected.

Adjust Displacement Display | 145


Animate the Results Now, create an animation of the results.

1 Click Animate

in the Result panel.

2 In the Animate Results dialog box, specify number of steps. Set the Steps edit field to 8. 3 Specify the playback speed. Select Normal in the Speed drop-down menu.

4 Click the Play playback.

command to see the animation. You can pause


5 When you finish the displacement animation, click OK to exit the animation playback. The Animate Results dialog box also has options for displaying the original wireframe with the plot. You can also record the animation to present or retain for records. Previous (page 144) | Next (page 147)

Generate Report We can generate a report of the simulation results which includes all the simulation data and outputs.

1 Click Report

in the Publish panel.

2 On the General tab, check the Custom box. 3 Switch to the Simulations tab, and make sure the Material and Cross Section in the tree are selected. 4 Switch to the Format tab and make sure the Web page – multiple files (.html) option is selected in the Report Format drop-down menu. 5 Click OK to close the dialog box and create the HTML report. Report contains text and PNG images that represent a static snapshot of the analysis results. Previous (page 146) | Next (page 148)

Generate Report | 147

Summary

Now you have an understanding of the tools you can use to view and interpret results of frame analysis. You know how to: ■ Display and edit diagrams. ■

View beam detail.

■

Adjust displacement display.

■

Display maximal and minimal values in the graphics window.

■

Animate results.

■

Generate report.

What Next? As a next step, look into creating advanced connections (releases and rigid links), and adding custom nodes to the beam model. The Frame Analysis Connections tutorial takes you through these topics. Previous (page 147)


Frame Analysis Connections

9

About this tutorial

Add and define connections to simulate interactions between assembly components in Inventor Frame Analysis. Category

Simulation

149

Time Required

30 minutes

Tutorial File Used

analyze_frame.iam

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. Prerequisites Familiarize yourself with the Frame Analysis environment by doing the Frame Analysis and Frame Analysis Results tutorials. Navigation Tips ■ Use Next or Previous at the bottom-left to advance to the next page or return to the previous one. Next (page 150)

Connections Overview In the analysis of a frame assembly, you create connections to define the relationship between beams. Connections transfer load between beams while preventing beams from penetrating each other. Connections can simulate interaction between beams that separate or come into contact during loading. Without connections, beams do not interact with each other in the simulation. There are two connection types you can use to simulate the physical behavior of a frame assembly. Rigid links are used to model rigid elements of elastic structures (definition of a rigid body in a structure). Displacements and rotations defined for a rigid link can be limited to certain selected degrees of freedom. You need at least two nodes to define a rigid link, one parent node and one or more child nodes. A parent node passes its parameters down to child nodes during simulation. Releases of specified degrees of freedom can be applied to start or the end of the beam with possible elasticity. Previous (page 149) | Next (page 151)

150 | Chapter 9 Frame Analysis Connections

Open the Assembly To begin with, we open the assembly to analyze. 1 Click the Open


2 Set the Project File to tutorial_files.ipj 3 Select Frame Analysis 1 ➤ analyze_frame.iam. 4 Click Open. 5 Click Save as to save the file with a different name, such as: analyze_frame_connections.iam



Frame Analysis Environment We are ready to enter the Frame Analysis environment. 1 On the ribbon, click Environments tab ➤ Begin panel ➤ Frame

Analysis

.

2 On the Manage panel, click the Create Simulation The Create New Simulation dialog box displays.

command.

3 Switch to the Model State tab. In the Design View drop-down menu, select Default. the default view displays the complete assembly that we want to analyze. 4 Click OK to close the dialog box. The Inventor model is automatically converted into idealized nodes and beams, and a simulation is created. The Gravity symbol also displays.



The browser populates with a hierarchical structure of the assembly and analysis-related folders. Most of the commands in the ribbon panels are now enabled for use. Disabled commands enable after you run the simulation. Previous (page 151) | Next (page 154)

Change Direction of Gravity When a simulation is created, gravity is automatically applied. In this tutorial, we change the direction of gravity. 1 In the browser, expand the Loads folder. Select Gravity and select Edit.

. Right-click

2 In the Gravity dialog box, select Z Direction from the drop-down list. 3 Click OK to close the Gravity dialog box. Previous (page 152) | Next (page 154)

Add Custom Nodes Next, we add nodes to the selected beams of the frame structure. Custom nodes are used for defining the loads, constraints, releases, and rigid links.

1 In the Connections panel, click Custom Node . A Heads Up Display (HUD) is used as the default edit method. It prompts you to select a beam where we place the custom nodes.


2 Select the beam as shown in the following image.

3 Enter 170 mm to the Offset edit field and click Done . Repeat the same steps to insert a second custom node to the same beam. Click the Custom Node command, select the beam, enter 2330 mm and click Done

.

4 Now, we insert custom nodes to the parallel beam. In the Connections

panel, click Custom Node

.

Add Custom Nodes | 155

5 Select the beam as shown on the image.

6 Enter 170 mm to the Offset edit field and click Done . Repeat the same steps to insert a second custom node to the same beam. Click the Custom Node command, select the beam, enter 2330 mm and click Done

.



Add Custom Nodes We also insert custom nodes to the rails under the cart wheels. Later, we use all these nodes to create rigid links.

1 In the Connections panel, click Custom Node

.


3 Enter 6080 mm to the Offset edit field and click Done . Insert a second custom node to the same beam. Right-click and select Repeat Custom Node. Select the same beam, enter 3920 mm and click Done .

Add Custom Nodes | 157

4 Now, we insert custom nodes to the parallel beam. In the Connections

panel, click Custom Node

.


6 Enter 6080 mm to the Offset edit field and click Done . Insert a second custom node to the same beam. Right-click, and select Repeat Custom Node. Select the same beam, enter 3920 mm and click Done . We inserted all custom nodes that we need for our analysis. Custom Nodes are listed in the Nodes folder in the browser. Their numbers were assigned in the order we defined them, starting from the first available node number.


NOTE You can also display the node numbers in the graphics window. In the

Display panel, click Node Labels

.


Change Color of Custom Nodes We can graphically differentiate custom nodes in the graphics window. 1 On the ribbon, in the Settings panel, click Frame Analysis Settings

. 2 On the General tab, in the Colors area, click the arrow button next to the Custom Nodes field. 3 On the Color dialog box, select a color for custom nodes. Select a red color box.

, and click OK to save the changes and exit the Color dialog

Change Color of Custom Nodes | 159

4 Click OK in the Frame Analysis Settings dialog box. All custom nodes now display in red color in the graphics window.


Assign Rigid Links Now we define the rigid links to create connections between selected nodes. We create rigid links between nodes located under and above the cart wheels.

1 In the Connections panel, click Rigid Link


.

2 The Parent Node button is automatically activated. Select the node as shown in the following image:

Assign Rigid Links | 161

3 The Child Nodes button activates. Select the node as shown on the image:

4 On the Rigid Link dialog box, in the Rotation area, clear the Y-Axis check box. The Rigid link is free to rotate about the Y-axis. Click Apply. 5 The Rigid Links dialog box remains open after we create our first rigid link. Define rigid links between nodes under and below remaining three cart wheels. Always, select the node below the wheel as a parent node, and a node above the wheel as a child node. For all rigid links, clear the Y-Axis check box in the Rotation area. In the image, see which nodes to select to create rigid links. When you define the last rigid link, click OK


to close the Rigid Link dialog box.

Assign Rigid Links | 163

6 Now, four new rigid links are created between selected custom nodes.


Add Constraints The simulation cannot be successfully performed without constraints. We insert constraints to four edge nodes on rails. NOTE Constraints are required for frame simulations. If you start a simulation without constraints, a dialog box opens and displays the error message: No constraints are defined.

1 In the Constraints panel, click Fixed


.

2 You are prompted to select an origin of the fixed constraint. Select any of the nodes at the end of rails. Order is not important because we insert fixed constraints to all these four nodes as shown in the following image.

NOTE A symbol is displayed at the node when the constraint is applied, and a node is added to the browser. 3 After you apply the first fixed constraint, right-click and select Repeat Fixed Constraint. Select another node at the end of beam rails. Use this method to place fixed constraints to all four nodes at the ends of rails. You can zoom in the graphics window to see if constraints are applied. Previous (page 160) | Next (page 165)






View the Results

After the simulation completes, the graphics window displays the Displacement results plot. The complete set of results is posted in the Results folder.


The status messages about the simulation display in the Status folder. Our simulation ran without any problems or errors so the Status folder is empty. There are various commands for viewing result data. Most of them are located in the Result and Display panels. Previous (page 165) | Next (page 167)

Assign a Release We now assign a release with free rotation to one of the rails below the cart. Notice that it gets much more deformed than the opposite rail.

1 In the Connections panel, click Release

.

Assign a Release | 167

2 Select the beam as shown in the image.

A beam coordinate system is shown while editing, closer to the start end of the beam. Also, symbols of degrees of freedom at start and end node of the beam display. The following symbols are used: ■

x means a “fixed” type of displacement or rotation

■

f means an “uplift none” type of displacement or rotation

■

f+ means an “uplift+” type of displacement or rotation

■

f- means an “uplift-“ type of displacement or rotation

3 In the Release dialog box, the uplift none options are set for all three rotational axes. Rotation is free to move in all directions. Accept the


default settings, and click OK to assign a release to the selected beam.


Run the Simulation Again Because we changed the inputs for our simulation, there is a browser icon next to the Results browser node. It indicates that results do not reflect current inputs. We must rerun the simulation to update results.

Run the Simulation Again | 169




View the Updated Results

After the simulation completes, the graphics display presents the Displacement results plot. Also, the icon disappeared from the Results browser node. The results now reflect current inputs and simulation properties.


You can see that the released rail is more deformed that the opposite rail without a release. Previous (page 169) | Next (page 171)

Summary

Now you have a basic understanding of how to work with a connection in frame analysis. You learned how to: ■ Create a simulation. ■

Change direction of Gravity.

■

Add custom nodes.

Summary | 171

■

Assign rigid links.

■

Set the degrees of freedom of rigid links.

■

Assign releases.

■

Run a simulation.

■

Viewing and interpreting the results.

What Next? As a next step, look into creating a modal type of frame analysis, and interpreting the modal frequencies. The Modal Type of Frame Analysis tutorial takes you through these topics. Previous (page 170)


Modal Type of Frame Analysis

10

About this tutorial

173

Perform a structural frequency (modal analysis) study to find natural mode shapes and frequencies of vibration. Category

Simulation

Time Required

15 minutes

Tutorial File Used

analyze_frame_tutorial.iam

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. The tutorial uses an Inventor assembly with frames and demonstrates the process of creating, solving, and viewing results. We use 3D plots to illustrate the various mode shapes and corresponding frequency values. Objectives ■ Create a modal simulation. ■

Change simulation properties.

■

Exclude components from simulation.

■

Run a simulation.

■

View the results.

■

Create an animation of results.

Prerequisites ■ Complete the Frame Analysis tutorial. ■



174 | Chapter 10 Modal Type of Frame Analysis

Open the Assembly To begin, we open the assembly to analyze. 1 Click the Open


2 Set the Project File to tutorial_files.ipj 3 Select Frame Analysis 1 ➤ analyze_frame_tutorial.iam. NOTE This assembly was created during the Frame Analysis tutorial. 4 Click Open. 5 Click Save as to save the file with a different name, such as: analyze_frame_modal_type.iam Previous (page 173) | Next (page 175)

Frame Analysis Environment Enter the Frame Analysis environment. On the ribbon, click Environments tab ➤ Begin panel ➤ Frame Analysis

. Previous (page 175) | Next (page 175)

Create a Simulation Study The Frame Analysis environment activates. We created a simulation during the Frame Analysis tutorial so the model with simulation results displays. The Displacement results plot displays in the graphics window, by default.


We change the simulation properties and create a modal analysis. 1 In the browser, select Simulation:1. Right-click, and select Edit Simulation. 2 In the Edit Simulation Properties dialog box, select Modal Analysis. Click OK. Previous (page 175) | Next (page 176)

Run the Simulation Because we changed the simulation properties, there is a browser icon next to the Results browser node indicating that results do not reflect current inputs.


We must rerun the simulation to updatethe results.




View the Results After the simulation completed, the icon disappeared from the Results browser node. The results now reflect current inputs and simulation properties. Also, a Modal Frequency folder was created under the Results browser node. Expand the Modal Frequency folder to expose the list of available Mode Shapes corresponding to each calculated natural frequency. Double-click the frequency of choice to display it. The following image shows the first three modal frequencies of the performed analysis.



Animate the Results Now you can perform post-processing tasks using the Result panel commands. These commands are described in Help. Create an animation:

1 Click Animate

in the Result panel.

2 In the Animate Results dialog box, specify the number of steps. Set the Steps edit field to 8. 3 Specify the playback speed. Select Normal in the Speed drop-down menu.

4 Click the Play playback.

command to see the animation. You can pause the

5 When you finish the displacement animation, click OK to exit the animation playback. The Animate Results dialog box has options for displaying the original wireframe with the plot. You can also record the animation to present or retain for records. Previous (page 177) | Next (page 179)


Summary

In this tutorial, you performed a structural frequency (modal analysis) analysis with the goal of finding natural mode shapes and frequencies of vibration. The steps performed include: ■ Create a modal simulation. ■

Change simulation properties.

■

Exclude components from simulation.

■

Run a simulation.

■

View the results.

■

Create an animation of results.

Previous (page 178)

Summary | 179

180

Dynamic Simulation Part 1

11

About this tutorial Simulate and analyze the dynamic characteristics of an assembly in motion under various load conditions. Category

Simulation

Time Required

40 minutes

Tutorial File Used

Reciprocating Saw.iam

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. Dynamic Simulation contains a wide range of functionality and accommodates numerous workflows. This tutorial helps you become familiar with the key paradigms and features of Dynamic Simulation. Then you can explore other capabilities, and apply Dynamic Simulation to your particular needs. Objectives ■ Recognize the differences between the Dynamic Simulation application and the regular assembly environment. ■

See how the software automatically converts mate assembly constraints to Dynamic Simulation standard joints.

181

■

Use Color Mobile Groups to distinguish component relationships.

■

Manually create rolling, 2D contact, and Spring joint types.

■

Define joint properties.

■

Impose motion on a joint and define gravity.

■

Use the Output grapher.

■

Run a dynamic simulation to see how joints, loads, and component structures interact as a moving, dynamic mechanism.

Prerequisites ■ Complete the Assemblies tutorial. ■

Understand the basics of motion.

■



Open the Assembly 1 To begin, set your active project to tutorial_files. 2 Open Dynamic Simulation 1 and 2 ➤ Reciprocating Saw.iam.

182 | Chapter 11 Dynamic Simulation - Part 1

3 Click name.

➤ Save As. Use RecipSaw-tutorial_1.iam for the

4 Click Save. As you work through the following exercises, save this assembly periodically. Previous (page 181) | Next (page 183)

Degrees of Freedom Before going further in the tutorial, it is good to understand the differences between the assembly modeling and dynamic simulation environments. Though both environments have to do with creating mechanisms, there are some critical differences between Dynamic Simulation and the Assembly environment. The basic difference has to do with degrees of freedom and how they are managed. In the assembly environment, unconstrained and ungrounded components have six degrees of freedom.

You add constraints to restrict degrees of freedom. For example, adding one flush constraint between this part and one of its canonical planes removes 3 degrees of freedom.

Degrees of Freedom | 183

In Dynamic Simulation, unconstrained and ungrounded components have zero degrees of freedom and will not move in a simulation. The addition of joints creates the degrees of freedom. When entering Dynamic Simulation, components that have mate constraints receive these joints automatically. With either Dynamic Simulation or the assembly environment, the intent is to build a functional mechanism. Dynamic Simulation adds to that functional mechanism the dynamic, real-world influences of various kinds of loads to create a true kinematic chain. Previous (page 182) | Next (page 184)

Automatic Constraint Conversion When you change from the assembly environment to the Dynamic Simulation environment, mate constraints are automatically converted into joints that match the mechanical function of those constraints. You can accept the joints as defined by the software, or you can modify or delete them as needed. 1 On the ribbon, click Environments tab ➤ Begin panel ➤ Dynamic Simulation.


NOTE If you are prompted to run the Dynamic Simulation Tutorial, click No. The Dynamic Simulation environment is active. You will notice that the browser and its nodes have changed for the simulation environment. In the simulation browser there are several folders for simulation objects. They relate to the simulation as follows: Grounded folder

Components with no degrees of freedom

Mobile Groups folder

Components with degrees of freedom allowing them to participate in the simulation when forces are applied. Each mobile group is assigned a specific color. Right-click the Mobile Groups folder and click Color Mobile Groups to visually determine mobile groups the component resides in.

Standard Joints folder

Joints created by automatic constraint conversion when entering the dynamic simulation environment. Contributing constraints are displayed as child nodes.

Various Joint folders

All non-standard joints that are created reside in folders for those specific joint types. Contributing constraints are displayed as child nodes.

External Loads folder

Loads that you define, including Gravity, are displayed in this folder.

NOTE Assemblies containing legacy, pre-Inventor 2008, Dynamic Simulation objects DO NOT have their constraints automatically converted upon entering the simulation environment. 2 Expand the Standard Joints folder.

Automatic Constraint Conversion | 185

These joints were automatically created based on the assembly constraint scheme. The software analyzes mate constraints and determines which joint will best equate with the constraint scheme. You can disable the automatic conversion of constraints, and then manually convert only those you want in the simulation. Note, however, that when you turn off automatic constraint conversion, all existing joints are deleted, including manually created joints, thereby removing all degrees of freedom. To disable automatic constraint conversion, click Dynamic Simulation

tab ➤ Manage panel ➤ Simulation Settings. Clear the check mark next to Automatically Convert Constraints to Standard Joints so that this option is no longer active. Click Yes, when prompted, then click OK on the dialog box. All joints in the assembly are deleted. To turn automatic constraint conversion back on, click the Simulation

Settings command and check the Automatically Convert Constraints to Standard Joints option. 3 Click OK. Standard joints are created. NOTE If you previously created non-standard joints in this assembly, these joints are deleted. 4 Expand the Mobile Groups folder. Components whose constraint scheme displays controlled motion have relationships built and are grouped based on the relationship. 5 Expand the Welded Group folder. Where a rigid relationship exists between components the software may create a welded group. There are no degrees of freedom between the members of a welded group. 6 Right-click the Mobile Groups folder, and click Color mobile groups. All members within a group are assigned a color by the software. This feature is used to easily identify members of a mobile group. 7 Right-click the Mobile Groups folder and click Color mobile groups again to turn off the group coloring. Previous (page 183) | Next (page 187)


Assembly Constraints 1 To see a component move, click and drag the Bevel Gear1 component.

The motion you see is borrowed from the assembly environment. Even though you are in Dynamic Simulation, you are not yet running a simulation. Since a simulation is not active, the assembly is free to move. NOTE Some motion associated with assembly constraints may not occur when doing this because those constraints are not automatically translated into joints. 2 In the Simulation Player floating window, click Run.

Assembly Constraints | 187

The Dynamic Simulation browser turns gray and the status slider on the simulation panel moves, indicating that a simulation is running. Although some joints were automatically created, the assembly displays no motion. This is because of insufficient input at this point. 3 Click Stop if the slider is still moving.

Even though the simulation is not running, the simulation mode is still active. If you attempt to drag the Bevel Gear component, there is no motion. 4 Click the Construction Mode command to leave the simulation run mode.

These relationships and behaviors may very well seem contradictory or confusing. Don't be concerned. As you progress through the following workflows, Dynamic Simulation and its paradigms will be revealed. Previous (page 184) | Next (page 189)


Add a Rolling Joint Now we need to build the relationship between the bevel gears. There are two bevel gears, a larger one associated with the cam action, and a smaller one associated with the motor assembly. We will work with the smaller gear to start with. 1 Expand the Mobile Groups folder and Motor node to reveal the Bevel Gear1 node. 2 Right-click the Bevel Gear node and click Edit. You are automatically placed in the Part editing environment. 3 In the browser, expand the Surface Bodies(1) folder. 4 Right-click the Srf1 browser node, and click Visibility. We will use the surface to help define the bevel gear relationship.

5 On the ribbon, click Return to go back to the simulation environment. Alternatively, right-click in the graphic area, and click Finish Edit. 6 On the ribbon, click Dynamic Simulation tab ➤ Joint panel ➤

Insert Joint

to display the Insert Joint dialog box.

7 In the drop-down list, select Rolling: Cone on Cone.

Add a Rolling Joint | 189

8 The component selector is automatically active, allowing you to begin selection. Select the Pitch diameter circle at the base of the surface cone.

9 Click the component 2 selector on Bevel Gear2.

, and select a conical face

You may have to expand the Mobile Groups and Cam crank browser nodes to see the second gear.

10 Click OK. 11 Click and drag the motor bevel gear. The Cam crank assembly moves because of the joint you created. 12 Edit the part again, and turn off Visibility of the Srf1 surface body. Previous (page 187) | Next (page 190)

Building a 2D Contact The next relationship that needs to be built is one between the cam Follower Roller and the cam component. The Follower Roller needs to contact the cam.


Retaining degrees of freedom The Follower Roller is a symmetrical part and, by default, dynamic simulation attempts to reduce symmetrical component movement. Why? An example will help. Consider a wheel assembly. You have a tire mounted to a rim. That assembly is attached to the vehicle with lug nuts.The function of a lug nut, for simulation purposes, isn’t to revolve around its axis; it is to constrain the assembly to the vehicle. Because the lug nut is a symmetrical component, the rotational degree of freedom (DOF) is automatically removed. This simplifies the model for simulation purposes. If you want to retain the lug nut’s rotational DOF, you can do so using the Retain DOF command. The same is true in reverse. That is, you can use Ignore DOF to restrict the degrees of freedom of a component. To ensure that the Follower Roller contacts the cam while also keeping its degree of freedom: 1 In the Mobile Groups folder, expand the Welded group. There are two components in the group. 2 Right-click the Follower Roller component, and click Retain DOF. The roller retains its motion characteristics. Now, we need to make sure the roller contacts the cam. 3 Click the Insert Joint command to display the dialog box. From the list, select 2D Contact. 4 Select the cam profile edge. 5 Select the sketch profile displayed on the roller component. As you can see, you can use sketch geometry as part of the simulation.

Building a 2D Contact | 191

6 Click OK. 7 Drag the Follower until it contacts the cam. It makes contact but does not penetrate the cam. The 2D contact established a mechanical relationship between the two components. Before going any further, we will modify the properties of the 2D contact and display the force vector. 8 In the browser, right-click the 2D contact joint, and click Properties.


9 Set the Restitution value to 0.0, and Friction to 0.15. 10 Expand the dialog box to access the lower section. Check the Normal box, and set the Scale to 0.003. 11 Click OK. Previous (page 189) | Next (page 193)

Add Spring, Damper, and Jack Joint The Follower is designed to slide through a portion of the Guide component. However, to hold the Follower Roller against the Cam, we must specify a

Add Spring, Damper, and Jack Joint | 193

spring between the Follower and Guide components. Dynamic Simulation offers a joint for doing that and more - the Spring/Damper/Jack joint. Depending on the joint type, the dialog box provides applicable inputs to help define the joint. 1 Click the Insert Joint command and in the dialog box, select Spring / Damper / Jack from the drop-down list of joint types. The Component 1 selector is active. 2 On the Guide component, select the hole profile where the Follower passes through the Guide.This creates one contact for the spring. 3 Select the edge profile where the spring will contact the follower.

4 Click OK. The result is a spring joint in the browser and a graphic representation of a spring. The representation is deformable and has action-reaction forces, but does not have mass.


5 In the browser Force Joints folder, right-click the Spring joint, and click Properties. 6 In the main section of the dialog box: ■ Set Stiffness to 2.500 N/mm. ■

Set Free Length to 42 mm.

Expand the dialog box and set: ■

Set Radius to 5.2 mm.

■

Set Turns to 10.

■

Set Wire Radius to 0.800 mm.

7 Click OK. The spring properties and graphical display update. Previous (page 190) | Next (page 195)

Define Gravity 1 In the browser External Loads folder, right-click Gravity, and then click Define Gravity. Alternatively, you can double-click the Gravity node. If necessary, clear the check mark next to Suppress.

Define Gravity | 195

2 Select the Case edge as shown in the image to specify a vector for gravity. You can use the Invert or Reverse directions.

command to change

3 Click OK. Note that the direction of gravity has nothing to do with any external notion of "up" or "down," but is set according to the vector you specify. Previous (page 193) | Next (page 196)

Impose Motion on a Joint To simulate saw operation, it is necessary to impose motion. In this case, we will apply motion to the motor, just as would be the real world case. To impose motion, you must edit the joint properties. 1 In the browser Standard Joints folder, right-click the Revolution:2 (Saw layout:1. Motor:1) joint, and click Properties.


2 Click the dof 1 (R) tab.

3 Click the Edit imposed motion command Enable imposed motion.

, and check

4 Click the arrow to expand the input choices, and click Constant Value. Specify 10000 deg/s (ten thousand). 5 Click OK. Previous (page 195) | Next (page 197)

Run a Simulation Because the simulation is of a high speed device, we will modify the simulation properties. 1 On the Simulation Player in the Final Time field, enter .5 s, which is sufficient to demonstrate the mechanism. TIP Use the tooltips to see the names of the fields on the Simulation Player.

NOTE The software automatically increases the value in the Images field proportionally to the change in the Final Time field. Press the Tab key to move the cursor out of the Final Time field and update the Images field. 2 In the Images field, enter 200. Increasing the image count improves the results we will view in the Output Grapher. 3 Click Run on the Simulation Player.

Run a Simulation | 197

As the Motor component drives the bevel gear, the remaining parts in the kinematic chain respond. Also, because we have not yet specified any frictional or damping forces, the mechanism is lossless. There is no friction between components, regardless of how long the simulation runs. 4 If the simulation is still running, click Stop on the Simulation Player. Before leaving the simulation run environment, we’ll take a look at the Output Grapher. Previous (page 196) | Next (page 198)

Using the Output Grapher The Output Grapher is the means to examine a variety of results from the simulation. The following list describes some of the things you can do after running a simulation: ■ Change reference frames to view results in various coordinate systems. ■

Display curve results.

■

Save the simulation results for later review and comparison.

■

Display results in terms of time or other criteria. 1 After running the simulation, but before leaving the run environment, on the ribbon click Dynamic Simulation tab ➤ Results panel ➤

Output Grapher

.

The Output Grapher is divided into different sections: browser, graph, and time steps. Commands specific to Output Grapher are located on a toolbar across the top of the window. The window is resizable, so adjust it to meet your needs. 2 In the browser of the Dynamic Simulation - Output Grapher window, expand the Standard Joints node. Then, expand the Revolution:2 node. 3 Under the Revolution:2 node, expand the Driving force node. Check the box next to U_imposed[1]. You will see the force displayed in the graph region. 4 Expand the Prismatic:3 node.


5 Expand the Velocities node, and check V[1]. The velocity is presented in the graph with the driving force.

6 Close the Output Grapher window. Previous (page 197) | Next (page 199)

Simulation Player Let's take a quick look at some features on the Simulation Player. As mentioned, the Final Time field controls the total time available for a simulation.

Simulation Player | 199

The Images field controls the number of image frames available for a simulation. Click Construction Mode , change this value to 100, and run the simulation. Click Construction Mode when the simulation is finished and change this value back to 200.

The Filter field controls the frame display step. If the value is set to 1, all frames play. If the value is set to 5, only every fifth frame displays, and so on. This field is editable when simulation mode is active, but not while a simulation is running.

The Simulation Time value shows the duration of the motion of the mechanism as would be witnessed with the physical model.


The Percent value shows the percent complete of a simulation.

The Real Time of Computation value shows the actual time it takes to run the simulation. This is affected by the complexity of the model and your computer's resources.

You can click Screen Refresh to turn off screen refresh during the simulation. The simulation runs, but there is no graphic representation.

Simulation Player | 201

Click the Construction Mode command to exit the simulation run environment. The construction mode is where you create and edit joints. IMPORTANT Save the assembly before exiting. This will enable you to go to the next tutorial and use this assembly as the basis for that tutorial. Previous (page 198) | Next (page 202)

Summary

You can also export load conditions at any simulation motion state to Stress Analysis. In Stress Analysis, you can see, from a structural point of view, how parts respond to dynamic loads at any point in the assembly's range of motion. In this tutorial, the skills you learned include: ■ Understanding basic differences between the Dynamic Simulation application and the regular assembly environment. ■

Having the software automatically convert relevant assembly constraints to Dynamic Simulation standard joints.

■

Use Color Mobile Groups to distinguish component relationships.

■

Manually creating rolling, 2D contact, and Spring joint types.

■

Defining joint properties.

■

Imposing motion on a joint and defining gravity.

■

Using Output graphers.


■

Running a dynamic simulation to see how joints, loads, and component structures interact as a moving, dynamic mechanism.

Remember to check the Help files for further information. And, remember to go online at autodesk.com for more tutorials and Skill Builders. Previous (page 199)

Summary | 203

204

Dynamic Simulation Part 2

12

About this tutorial

Add the blade assembly and complete the operating conditions definition, modify the cam lobe, and then publish the simulation with Inventor Studio. Category

Simulation

Time Required

20 minutes

Tutorial Files Used

Used in the tutorial: RecipSaw_tutorial_1.iam Blade set.iam

205

Completed file: Reciprocating Saw FINAL.iam

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. In this tutorial, we pick up where we left off in the Dynamic Simulation Fundamentals - Part 1 tutorial. Objectives ■ Add the saw blade subassembly. ■

Add various joints.

■

Impose motion, friction, and retain degrees of freedom in subassemblies.

■

Add traces.

■

Publish a simulation animation using Inventor Studio.

Prerequisites ■ Complete the Dynamic Simulation Fundamentals - Part 1 tutorial. ■

Complete the Studio - Animations tutorial.

■

Understand the basics of motion.

■



Work in the Simulation Environment Understanding Simulation Commands Large and complex moving assemblies coupled with hundreds of articulated moving parts can be simulated. The Autodesk Inventor Simulation provides: ■ Interactive, simultaneous, and associative visualization of 3D animations with trajectories; velocity, acceleration, and force vectors; and “deformable” springs.


■

Graphic generation command for representing and post-processing the simulation output data.

Simulation Assumptions The dynamic simulation commands provided in Autodesk Inventor Simulation help in the steps of conception and development and in reducing the number of prototypes. However, due to the hypothesis used in the simulation, it only provides an approximation of the behavior seen in real-life mechanisms. Interpreting Simulation Results To avoid computations that can lead to a misinterpretation of the results or incomplete models that cause unusual behavior, or even make the simulation impossible to compute, be aware of the rules that apply to: ■ Relative parameters ■

Coherent masses and inertia

■

Continuity of laws

Relative Parameters The Autodesk Inventor Simulation uses relative parameters. For example, the position variables, velocity, and acceleration give a direct description of the motion of a child part according to a parent part through the degree of freedom (DOF) of the joint that links them. As a result, select the initial velocity of a degree of freedom carefully. Coherent Masses and Inertia Ensure that the mechanism is well-conditioned. For example, the mass and inertia of the mechanism should be in the same order of magnitude. The most common error is a bad definition of density or volume of the CAD parts. Continuity of Laws Numerical computing is sensitive toward discontinuities in imposed laws. While a velocity law defines a series of linear ramps, the acceleration is necessarily discontinuous. Similarly, when using contact joints, it is better to avoid profiles or outlines with straight edges. NOTE Using little fillets eases the computation by breaking the edge. Previous (page 205) | Next (page 208)

Work in the Simulation Environment | 207

Construct the Operating Conditions We will now complete the motion definitions so that the simulation reflects product operating conditions. If the RecipSaw-tutorial_1.iam assembly is not open, open the file to continue. As you can see, although we have the saw body, we do not have the blade components. To add the blade components it is not necessary to leave the simulation environment. NOTE Make sure you are in Construction Mode before performing the next steps. 1 Click the Assemble tab to display the Assembly ribbon. 2 In the Component panel, click Place Component. Select Dynamic Simulation 1 and 2 ➤ Blade set.iam and click Open. 3 Position the Blade set assembly near where it will be assembled.

4 Right-click in the graphics window, and click Done. 5 In the browser, expand the Blade set assembly node to display the components.


6 Select the Scottish Yoke component. In the Quick Access toolbar, change the appearance to Chrome. NOTE If you receive an Associative Design View Representation message about appearance associativity, select Remove associativity and click OK. 7 Add a Mate constraint between the Scottish Yoke and the Guide to position the yoke on top of the guide.

8 Add a second Mate constraint between the two components to position the yoke within the guide rails. Notice that in the simulation browser, under Standard Joints, a prismatic joint was created based on adding those constraints.

Construct the Operating Conditions | 209


Add Friction The mechanism thus far is lossless; meaning that it operates without friction or dampening as would normally be experienced. We will now add friction to capture the operating environment. Add Friction and complete the yoke-guide relationship 1 In the browser, right-click Blade set.iam, and click Flexible. By setting the assembly to Flexible, the assembly is placed into the welded group folder. Within that assembly, the constraints are evaluated and the constraint between the yoke and blade causes the addition of a Revolution joint.


2 As previously mentioned, the assembly has no friction yet. This step imposes friction on the prismatic joint. Right-click the Prismatic Joint for the Guide and the Scottish Yoke, and click Properties. 3 Click the dof 1 (T) tab.

4 Click the Edit joint force command

.

5 Click Enable joint force. 6 Enter a Dry Friction coefficient of 0.1, and click OK. 7 Now, you must add a constraint to position the Scottish Yoke with respect to the crank assembly. First, set the browser view to Model, and expand the Blade set.iam node. 8 Expand the Scottish Yoke node, and click the Constrain command. 9 In the browser, select Work Plane3 under the Scottish Yoke component. 10 In the graphics window, select a circular edge of the Roller component that is part of the Crank cam assembly. A Point-Plane joint is added to reflect the constraint.

Add Friction | 211

11 Click OK to add the constraint and close the dialog box. 12 Set the browser view back to Dynamic Simulation. The resulting Point-Plane joint has five degrees of freedom and one constraint. It is enough definition to transfer motion without over constraining the model. Dynamic Simulation detects over-constrained conditions and helps you to resolve them. Previous (page 208) | Next (page 212)

Add a Sliding Joint The interface between the Blade set and the saw drivetrain is not yet completely defined. We must have the follower end interact with the Blade Clamp component. It requires a sliding joint. 1 The next joint to add is the one between the Blade Clamp and the Follower, so that the Follower travels in the blade clamp. If the Dynamic Simulation tab is not active, select it. 2 Before creating the joint, it helps to lock the Prismatic Joint between the Guide and Follower components. This prevents the related components from moving and lets the solver work more efficiently. Right-click the Prismatic:3 (Guide:1, Follower:1) joint, and click Lock dofs.


3 Add the sliding joint. To do this, click Insert Joint. In the drop-down list, select Sliding: Cylinder Curve. For input 1, select the blade clamp slot profile on which the Follower rides. 4 For input 2, select the Follower cylinder face that rides in the slot. Click OK.

5 Unlock the Prismatic Joint. That completes this section on adding components and joints to the assembly. In this section, you learned about: ■ Adding assembly components while in the simulation environment. ■

Adding assembly constraints and seeing them automatically create standard joints.

■

Adding joints to simulate mechanical conditions within the assembly.


Use the Input Grapher The Input Grapher provides a means of adding forces and torques that change during the simulation based on other independent variables.

Use the Input Grapher | 213

We will add an external force that is dependent on the velocity in the prismatic joint between the Guide and Scottish Yoke. To provide a sense of the velocity we use + or - values to define an opposite force. 1 In the browser, in Standard Joints, select the joint Prismatic (Guide:1, Scottish Yoke:1). Note that in the reference frames, when the velocity is positive, the reference frames point away from the blade end. If the reference frames point toward the saw blade, you may have to edit the joint to reverse the direction.

2 In the Load panel, click the Force command. Select a vertex of one of the saw teeth.


3 Click the Direction selector in the dialog box. 4 Select the top edge of the saw blade that is parallel with the blade motion.

5 Click the arrow on the Magnitude input control to display the list options, and click Input grapher.

The Input Grapher dialog box displays for the remaining steps. 6 Click the Reference selector, and in the Select Reference dialog box, expand Standard Joints > Prismatic (Guide:1, Scottish Yoke:1)

Use the Input Grapher | 215

to reveal the Velocities folder and contents. Click V(1) to specify velocity as variable for the graph X axis.

7 Click OK. Notice in the graph region the X axis of the graph shows the reference you just specified. When navigating inside the graph region. ■

You can roll the mouse wheel, if you have one, to zoom in and out.

■

To Pan the graph, click and drag the middle mouse button or wheel and watch the cursor move around the graph region.


8 In the lower section of the Input Grapher, for the Starting Point section, set X1 = -10 mm/s and Y1 = 250 N. 9 In the Ending Point section, set X2 = -0.1 mm/s and Y2 = 250 N. 10 Double-click in the graph area to the right and below the second point. This adds a new point, effectively creating a section in the graph. NOTE You can also right-click beyond the second point and click Add Point to start a new section. To select the second section, click on the line between the points. 11 The Starting Point for the second section (X1, Y1) is the previous section end point and is already set. To specify the second section Ending Point, set X2 = 0.0 mm/s and set Y2 = -250 N. 12 Add a third section to the right of the second section. To specify the third section Ending Point, set X2 = 10.0 mm/s and Y2 = -250 N. 13 Click OK to close the Input Grapher. 14 Expand the dialog box and check the Display option at the bottom. You can also specify a different color to differentiate the force visually. 15 Click OK to accept the input and close the Force dialog box. 16 Run the simulation. Do not leave the Run environment. Previous (page 212) | Next (page 217)

Use the Output Grapher The Output Grapher allows you to examine various results from the simulation. The following is a list of some of the things you can do after running a simulation: ■ Display vectors for internal or external forces. ■

Change reference frames to view results in various coordinate systems.

Use the Output Grapher | 217

■

Display curve results.

■

Save the simulation results for later review and comparison.

■

Display results in terms of time or other criteria.

■

Display traces to visualize trajectory of component points.

Display Traces 1 After running the simulation, and before leaving the run environment, click the Output Grapher command. The Output Grapher window is divided into different sections: browser, graph, and time steps. Output Grapher commands are located in a toolbar across the top of the window. The window is resizable, so adjust it to meet your needs. 2 Click Add Trace . The dialog box displays, and the Origin selector is actively awaiting an input. Select the point at the end of the saw blade. 3 In the dialog box, check the Output trace value option and click

Apply. 4 Add two additional trace points along the saw blade in the same manner, and be sure to export the trace for each point.


5 Close the dialog box. Set Trace as Reference 1 In the Output Grapher browser, expand Traces. 2 Expand Trace:1, and then Positions. 3 Right-click P[X], and click Set as Reference. 4 Use the Output Grapher Save command to save the Simulation. 5 Enter the name RecipSaw_tutorial_1.iam, and click Save. 6 In the grapher browser, right-click P[X] and uncheck Set as Reference. 7 Close the Output Grapher. 8 Click Construction Mode in the Simulation Player. As you can see, you can save simulation data, make changes, and compare the change results with the previous data. Previous (page 213) | Next (page 219)

Export to FEA Next we will export motion loads and run a stress simulation on a component. Use the following process for every component you want to analyze in the stress analysis environment. Select the component Use the following process for each component you want to analyze in FEA: 1 Run the simulation. 2 Open the Output Grapher. 3 In the Output Grapher toolbar, click Export to FEA. 4 In the simulation browser, select Follower:1 and click OK. The dialog box for selecting load bearing inputs is displayed. Select faces Three joint inputs are required to satisfy the motion requirements for exporting the Follower component. 1 In the graphics window, select the long shaft of the Follower component, which satisfies the prismatic joint input.

Export to FEA | 219

2 In the dialog box, click Revolution 5. 3 Select the small shaft that is used with the Follower Roller.

4 In the dialog box, click the Spring joint. 5 In the graphics window, click the face where the spring contacts the follower, and click OK.


Next, specify the time steps to analyze: 1 Click the Deselect all command in the Output Grapher toolbar. 2 Expand the Standard Joints, Revolution:5, and Force folders. Click Force. 3 Expand the Force Joints, Spring / Damper / Jack joint, and Force folders. Click Force. 4 In the graph region, double-click a Force (Revolution) graph high point you want to analyze. In the time steps section above the graph, place a check mark next to the corresponding time step.

Export to FEA | 221

5 Using the same method, select a low point of the Force (Revolution) values. Place a check mark next to its time step. 6 Close the Output Grapher. Import into Autodesk Inventor Stress Analysis 1 Click Finish Dynamic Simulation. 2 On the Environments tab, click Stress Analysis to open in the Stress Analysis environment. 3 In the Manage panel, click Create Simulation. 4 In the dialog box, under Static Analysis, select the Motion Loads Analysis option. The two list controls below the option are enabled and populated with the exported parts and time steps. 5 In the Part list, select the Follower component. 6 In the Time Step list, select a time step to analyze. 7 Click OK. The assembly updates to represent that time step and then isolates the Follower component for analysis. You can observe symbols representing the various forces acting on the Follower.

8 Click Mesh Settings, then click Create Curved Mesh Elements.


9 In the Solve panel, click Simulate, and then click Run. Wait for the simulation to complete. 10 Select from the various Results data to see how the component performs at that time step.

11 Click Finish Stress Analysis to exit the Stress Analysis environment. Previous (page 217) | Next (page 223)

Publish Output in Inventor Studio You can publish the simulation in Inventor Studio and produce high quality video output containing lighting, shadows, backgrounds, and so on. 1 Reenter the Dynamic Simulation environment and run the simulation. After running the simulation, do not leave the run environment.

2 In the Animate panel, click Publish to Studio.

Publish Output in Inventor Studio | 223

3 In the Studio environment, set up the following for your simulation: ■ Camera position, type, and associated settings. ■

Lighting style and its associated settings.

■

Scene style and its associated settings.

■

Different appearances, if desired.

If you are not experienced with Inventor Studio, take time to complete a Studio tutorial to get familiar with the animation commands it provides. Then, return to this part of the Dynamic Simulation tutorial and output your simulation to Studio.

4 Click the Animation Timeline command timeline.

to display the

5 Set the timeline slider to the time at which the animation action is to end, such as 2 seconds. 6 In the browser, expand the Animation Favorites folder. Right-click the Simulation Timeline parameter, and click Animate Parameters

. 7 Set the Action End value to 200 ul. 8 Click OK. 9 In Studio, add lighting and scene styles as needed. Create the camera angles you will use and complete the preparation of your animation. NOTE If you have not used Inventor Studio to create animations previously, you may want to do the rendering and animation tutorials, which cover the information for this step.

10 Click the Render Animation command

.

11 On the General tab, the styles you set up are the active ones. If not, select them from the various lists. 12 On the Output tab, click the box next to Preview No Render. It produces a test render for reviewing the animation action. Click OK to render a preview.


13 Once you confirm the animation is playing like you want, cancel the Preview option and render the simulation final animation with lighting and scene styles. Click OK to render a realistic-looking simulation. NOTE You may want to render images at a few different time positions to ensure the lighting and scene styles look like you expect, then render the animation. 14 Save the assembly. Previous (page 219) | Next (page 225)

Summary In this tutorial, we demonstrated a workflow to add components to an assembly while in the Dynamic Simulation environment. We added the blade assembly and completed the operating conditions definition. Then we modified the cam lobe, and finally published the simulation with Inventor Studio. In this tutorial, you: ■ Added the saw blade subassembly. ■

Added various joints.

■

Imposed motion, friction, and retained degrees of freedom in subassemblies.

■

Added traces.

■

Published a simulation animation using Inventor Studio.

What Next? - As a next step, consider completing one of the following tutorials: ■ Assembly Motion and Loads for a Cam and Lobe simulation ■

FEA using Motion Loads for exporting Motion Loads to stress analysis

■

Studio - Renderings for great looking images

■

Studio - Animations for creating animations of your product

Previous (page 223)

Summary | 225

226

Assembly Motion and Loads

13

About this tutorial

Simulate a cam and valve assembly. Category

Simulation

227

Time Required

25 minutes

Tutorial Files Used

cam_valve.iam

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. In this tutorial, you simulate a cam, valve, and spring mechanism. You determine the contact forces between the cam and valve, the forces in the spring, and the torque required to drive the cam. In addition, you view the simulation results in the Output Grapher, and export the simulation data to Microsoft Excel. Objectives ■ Create a spring. ■

Create a 2D Contact joint.

■

Impose a motion.

■

Simulate dynamic motion.

■

View the simulation results.

■

Export the simulation results to Excel.

Prerequisites ■ It is recommended that you first complete the Dynamic Simulation Fundamentals - Part 1 tutorial. ■

Understand the basics of motion and how it affects your design.

■

Know how to set the active project, navigate in model space with various view commands, and perform common modeling functions such as sketching and extruding.

■

See the Help topic, Getting Started, for more information.


228 | Chapter 13 Assembly Motion and Loads

Open Assembly To begin: 1 Set the active project to tutorial_files. 2 Open Dynamic Simulation 3 ➤ cam_valve.iam.

Open Assembly | 229

3 Use Save As to save a copy of this file with the file name cam_valve_tutorial.iam. Previous (page 227) | Next (page 231)


Activate Dynamic Simulation 1 On the ribbon, select Environments tab ➤ Begin panel ➤ Dynamic Simulation. The Dynamic Simulation tab displays in place of the previous tab.

2 If you are prompted to run the Dynamic Simulation Tutorial, click No. In the following pages, you specify the joints and forces necessary to create a simulation. Previous (page 229) | Next (page 231)

Automatic Joint Creation By default, Dynamic Simulation automatically converts assembly constraints to joints for assemblies created in the Autodesk Inventor 2008 or later releases. The Dynamic Simulation browser lists two joints: a revolution joint between the cam and the support, and a prismatic joint between the valve and the support. To complete the mechanism, you manually add a spring joint and a 2D contact joint. TIP Automatically created joints are maintained in the Standard Joints folder. Joints that you add otherwise, reside in other folders based on the joint type. TIP To delete automatically created joints, on the ribbon click Dynamic Simulation tab ➤ Manage panel ➤ Simulation Settings, and then remove the checkmark next to Automatically Convert Constraints to Standard Joints. Click No, when prompted, and click OK or Apply in the dialog box. Previous (page 231) | Next (page 232)

Activate Dynamic Simulation | 231

Define Gravity 1 In the browser, under External loads, right-click Gravity, and then select Define Gravity. 2 To define a vector for gravity, select one of the vertical edges of the support. Click the image to play the animation.

3 If the direction arrow points up, click Invert Normal arrow.

to flip the

4 Click OK. 5 Click Run on the Simulation Player. The valve responds to the force of gravity and drops away from the mechanism. 6 On the Simulation Player, click Construction Mode

.


Insert a Spring Before you insert the spring, make an adjustment to the mechanism. 1 If you have not already done so, you must return to the Construction Mode. In the Simulation Player, click Construction Mode

.

2 In the browser, right-click the prismatic joint, and then select Properties. 3 Select the dof 1 (T) tab. 4 In the Position field, enter 8 mm, and press the Tab key to update the assembly. The valve moves so that the two reference frame origins are separated by 8 mm. 5 Click OK.


6 On the ribbon, click Dynamic Simulation tab ➤ Joint panel

➤ Insert Joint. 7 Select Spring/Damper/Jack from the drop-down menu (the joint is located near the bottom of the menu). 8 This joint requires two selections. Select the circular edge on the support. 9 Select the circular edge on the valve. 10 Click OK.

Insert a Spring | 233



Define the Spring Properties 1 Expand Force Joints in the browser. Right-click the spring in the browser, and remove the checkmark next to Suppress to make the spring active. 2 Right-click the spring, and select Properties. 3 Enter 1 N/mm in the Stiffness field. 4 Enter 50 mm in the Free Length field to put a small preload on the spring. TIP Double-click the existing value in the input fields to select the entire string. 5 Click More

to expand the dialog box.

6 Enter 12 mm in the Radius field. NOTE The values in the Dimensions and Properties fields affect only the appearance of the spring, not its physical properties. 7 Click OK.

Define the Spring Properties | 235


Run the Simulation 1 Click Run on the Simulation Player to show the effect of the spring. The valve oscillates slightly due to gravity and the spring preload. 2 Return to Construction Mode. Previous (page 235) | Next (page 237)


Insert a Contact Joint Next, you add a joint between the cam and the valve.

1 Click Insert Joint. 2 Select 2D Contact from the drop-down menu. 3 Select the sketch loop on the cam lobe, as shown.

4 Select the sketch loop on the top of the valve stem, as shown.

Insert a Contact Joint | 237

NOTE Make sure that you select the sketch and not surrounding geometry. You may need to zoom in or use Select Other to select the loop. 5 Click OK. The contact joint is created and added to the newly added Contact Joints group in the browser. Previous (page 236) | Next (page 239)


Edit the Joint Properties 1 Click the View Face command the cam.

, and then select the front face of

2 In the browser, expand Contact Joints. Right-click 2D Contact, and select Properties. The Z axis of the cam points away from the cam. If the Z axis pointed inward, you would open the properties dialog box for the 2D contact joint and invert the normal direction of the Z axis for the cam. Likewise for the valve, if the Z axis pointed inward, you would invert the Z axis.

Edit the Joint Properties | 239

The fact that the Z axis points away from the cam indicates that it is the outer surface of the part rather than the inner surface of a hole or cut. In this case, the Z axis must always point out away from the part material rather than into the part material. 3 Expand the dialog box, then select Normal, and set the scale to 0.003. 4 Select Tangential, and set the scale to 0.01. 5 Click OK.



Add Imposed Motion Next, you add an imposed motion to specify the required rotation of the cam. 1 In the browser, expand Standard Joints. 2 Right-click the revolution joint, and select Properties. 3 Click the dof 1 (R) tab.

4 Click Edit imposed motion. 5 Select Enable imposed motion. 6 In the Driving field, ensure that Velocity is selected. 7 Click the arrow next to the velocity input box, and then select Constant value. 8 Change the value to 360 deg/s. 9 Click OK. Previous (page 239) | Next (page 241)

View the Simulation Results 1 Click Run on the Simulation Panel. 2 Allow the simulation to run. 3 On the ribbon, click Dynamic Simulation tab ➤ Results panel

➤ Output Grapher box.

to activate the Output Grapher dialog

4 In the Output Grapher browser, expand cam_valve_tutorial ➤ Contact Joints ➤ 2D Contact ➤ Point1 ➤ Force, and then select Force[1][Z]. 5 In the Output Grapher browser, expand cam_valve_tutorial ➤ Force Joints ➤ Spring/Damper/Jack ➤ Force, and then select Force[Y].

Add Imposed Motion | 241


View the Simulation Results (continued) View the results in the graph.

1 Arrange the Output Grapher and the model until you can view both simultaneously. 2 Double-click anywhere within the graph. A vertical black line appears. 3 While the Output Grapher still has the focus, press the right and left arrow keys on the keyboard to step through the simulation one time step at a time. Observe both the graphical results and the model. Previous (page 241) | Next (page 243)


Export the Data 1 On the Output Grapher toolbar, click Export Data to Excel

.

2 Click OK to accept the default chart output. 3 In the Save Value Filter, click OK to accept the default. 4 View the chart and data in Microsoft Excel, then close Microsoft Excel. Do not save the file. 5 On the Output Grapher toolbar, click Deselect All

.

6 In the Output Grapher browser, expand cam_valve_tutorial ➤ Standard Joints ➤ Revolution:1 (support:1, cam:1) ➤ Driving force, and then select U_imposed[1]. 7 In the Simulation Player, click Run, and observe the graph and assembly to see the correlation between the graph and the motion in the assembly. 8 Close the Output Grapher. 9 You can close the assembly without saving changes. Previous (page 242) | Next (page 244)

Export the Data | 243

Summary

This tutorial provided an overview of how to link a cam and valve, how to create a spring device, and how to use the Output Grapher to view simulation results. You learned how to: ■ Create a spring. ■

Create a 2D Contact joint.

■

Impose a motion.

■

Simulate dynamic motion.

■

View the simulation results.

■

Export the simulation results to Microsoft Excel.

Try applying what you have learned to models you create. Previous (page 243)


FEA using Motion Loads

14

245

About this tutorial

Generate and export motion loads. Category

Simulation

Time Required

20 minutes

Tutorial File Used

Windshield Wiper.iam

246 | Chapter 14 FEA using Motion Loads

NOTE Click and read the required Tutorial Files Installation Instructions athttp://www.autodesk.com/inventor-tutorial-data-sets . Then download the tutorial data sets and the required Tutorial Files Installation Instructions, and install the datasets as instructed. Use Dynamic Simulation to generate loads to export and use in Stress Analysis. Objectives ■ Export motion loads for use in stress analysis. Prerequisites ■ Complete the Dynamic Simulation - Part 1 tutorial. ■

Know how to set the active project, navigate the model space with the various view tools, and perform common modeling functions, such as sketching and extruding.

■



Open Assembly File 1 To begin, set your active project to Tutorial_Files. 2 Open Dynamic Simulation 4 ➤ Windshield Wiper.iam.

Open Assembly File | 247

3 On the ribbon, click Environments tab ➤ Begin panel ➤ Dynamic

Simulation to switch to the Dynamic Simulation environment. The dynamic simulation commands populate the ribbon bar. 4 If you are prompted to view the Dynamic Simulation tutorial, click No. 5 If a message warns that the mechanism is overconstrained, click OK. The redundancy is not important for the purposes of this tutorial. Previous (page 246) | Next (page 249)


Run a Simulation To generate the motion loads, you run a simulation and then export the loads to Stress Analysis. 1 Click the Run command on the Simulation Player to run the simulation. Allow the simulation to finish.

2 When the simulation finishes, click Output Grapher on the Results panel.

located

You use the Output Grapher to select and export the motion loads. Previous (page 247) | Next (page 249)

Generate Time Steps 1 In the Output Grapher browser, nested under Export to FEA, right-click Time Steps, and then select Generate Series. 2 In the Generate Time Steps dialog box, enter 16 in the Number of Steps field. 3 Ensure the Between Time Steps option is selected. 4 Take the default start time of 0 s. 5 Enter 4 s (the duration of this simulation) in the End field. 6 Click OK. These values generate four load intervals per second, for four seconds. The time step series is added to the Output Grapher browser. Previous (page 249) | Next (page 249)

Export to Stress Analysis 1 On the toolbar located at the top of the Output Grapher, select the

Export to FEA command. You are prompted to select a part to analyze.

Run a Simulation | 249

2 Select the Crank Sway part. You can orbit the assembly or use Select Other to access the part.

NOTE You can select more than one part to export. You cannot select parts within a subassembly unless the subassembly is set to Flexible. 3 In the Export to FEA dialog box, click OK. Next, you specify the load bearing faces. For this part, the holes on either end of the arm contain the load bearing faces. 4 For the Point-Line joint, select the face as shown.


5 In the dialog box, select the Revolution joint to complete the field. 6 Select the other face as shown.

Export to Stress Analysis | 251

NOTE Alternatively, you could use the Automatic Face Selection option to allow the software to select the load-bearing faces automatically. 7 Click OK. The loads are exported and ready for retrieval in Stress Analysis. 8 Close the Output Grapher.



Use the Motion Loads in Stress Analysis 1 In the Exit panel, click Finish Dynamic Simulation, then click

Environments tab ➤ Stress Analysis environment becomes active.

2 Click the Create Simulation

. The stress analysis

command.

3 In the Create New Simulation dialog box, on the Simulation Type tab, check the box next to Motion Loads Analysis. 4 In the Part list box, select the Crank Sway component. The list displays all components that were exported to FEA. 5 Next, specify the Time Step to be analyzed. The Time Step list displays all 16 time steps from the Dynamic Simulation environment. You choose the time step to analyze.

Use the Motion Loads in Stress Analysis | 253

6 Click OK. The loads for the time step you specified are added to the browser, nested under the Loads node. 7 Click the Simulate command to run the solution.


8 When the simulation finishes, evaluate the results for that motion interval. Previous (page 249) | Next (page 256)

Use the Motion Loads in Stress Analysis | 255

Generate a report Finally, you can generate a report of the analysis results. The report pertains to the selected time step at the time the report is generated.

1 In the Report panel, click Report. 2 In the Report dialog box, specify the information you want included in the report. ■ If you want a complete report, click OK and the report will proceed. ■

If you want only certain information in the report, click Custom and then specify the content for the report.

The report displays in your internet browser or as a Word document, depending on the output format you select. The report and associated files are saved to the location designated in the Report dialog box. By default, this location is the same as the part or assembly you are analyzing. If you want to save multiple reports, do one of the following ■ Use Save As in your internet browser to save a copy of each report. ■ Rename the report file and generate an additional report. Repeat as appropriate.



Summary

In this tutorial, you learned how to: ■ Generate motion loads for a selected part. ■

Access and use those loads within Stress Analysis.

■

Generate reports of analysis results.

Remember to check Help for further information. Previous (page 256)

Summary | 257

258

Index relative parameters results 207

C coherent masses and inertia continuity of laws 207

207

207

O

D

Output Grapher

dynamic simulation assumptions 207 coherent masses and inertia continuity of laws 207

R 207

relative parameters

208, 217

207

259 | Index

260

Stress Analysis INVENTOR

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