Workshop Table of Contents 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Workshop Table of Contents
1.
No W orkshop
6.2 Using Joints
WS6.2
2.1 ANSYS Mechanical Basics
WS2.1
7.1 Remote Boundary Conditions
WS7.1
3.1 Gear and Rack Analysis
WS3.1
7.2 Constraint Equations
WS7.2
3.2 Named Selections
WS3.2
8.1 Multistep Analysis
WS8.1
3.3 Object Generator
WS3.3
9.1 Vibration Analysis
WS9.1
4.1 Meshing Control
WS4.1
10.1 Steady State Thermal Analysis
WS10.1
5.1 Linear Structural Analysis
WS5.1
11.1 Mesh Evaluation
WS11.1
5.2 Using Beam Connections
WS5.2
12.1 Parameter Management
WS12.1
6.1 Contact Offset Control
WS6.1
– Appendix A Linear Buckling Analysis Appendix Submodeling B–
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Workshop 2.1 ANSYS Mechanical Basics 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Notes on Workshop 2.1 Please Note: The step by step instructions for this workshop do not begin until slide #6. The first workshop is extensively documented. As this course progresses, students will become more familiar with basic Workbench Mechanical functionality (menu locations etc.), thus subsequent workshops will contain less details. Throughout these workshops menu paths are documented as: “First pick > Second pick > etc.”.
Workshops begin with a goals section followed by an assumptions section.
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Goals Using the Stress Wizard, set up and solve a structural model for stress, deflection and safety factor. Problem statement: •
• •
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The model consists of a STEP file rep resenting a control box cover (see figure). The cover is intended to be used in an external pressure application (1.0 MPa). The cover is to be made from aluminum alloy. Our goal is to verify that the part will function in its intended environment.
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Assumptions We will represent the constrains on the counter bores, bottom contact area and inner sides using frictionless supports. •
Frictionless supports place a normal constraint on an entire surface. Translational displacement is allowed in all directions except into and out of the supported plane. Since we would expect frictional forces to act in th ese areas, this is a conservative approach.
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Environment Loads: the load consists of a 1 MPa pressure applied to the 17 exterior surfaces of the cover.
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Project Schematic Open the Project page. From the “Units” menu verify: •
Project units are set to “Metric (kg, mm, s, ºC, mA, N, mV).
•
“Display Values in Project Units” is checked (on).
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. . . Project Schematic 1. From the Toolbox choose create a Static Structural system (drag/drop or RMB).
1.
2. 2. RMB in the Geometry cell and Import Geometry. Browse to the file “Cap_fillets.stp”.
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Preprocessing 3. Double click the “Model” cell to open the Mechanical application. When the Mechanical application opens the model will display in the graphics window and the Mechanical Application Wizard displays on the right.
3.
When Mechanical starts if the Wizard is not displayed, use the icon to open it.
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. . . Preprocessing 4. Set/check the units system: •
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From the main menu go to “Units > Metric (mm, kg, N, s, mV, mA).
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. . . Preprocessing 5. Select a suitable material for the part:
a. From the Mechanical Wizard choose “Verify Material” b. Notice the callout box indicates Engineering Data is accessible from the WB2 interface (Project Schematic).
a. b.
c. Return to the Project schematic window and double click “Engineering Data” to access the material properties.
c.
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. . . Preprocessing 7. Activate the Data S ource to ggle and highlight “General Materials” then click the ‘+’ next to “Aluminum Alloy”.
7.
8. Return to the Project.
•
Notice the Model cell indicates a refresh is necessary.
8.
9. Refresh the Model cell (RMB), then return to the Mechanical window. 9.
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. . . Preprocessing 10. Highlight “Part 1” and click the “Material > Assignment” field to change the material property to aluminum alloy.
10.
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. . . Preprocessing 11. Insert Loads:
a. Select “Insert Structural Loads” from the Wizard b. Follow the call out box to insert a “Pressure” load c. The tree will now include a Pressure load in the “Static Structural” environment branch
a. b.
c.
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. . . Preprocessing 12. Apply the l oad to geometry:
a) b) c) d)
Highlight one of the outer faces of the part. Use the “Extend to Limits” icon to select the remaining 16 faces (total 17 faces selected). Click “Apply” to accept the faces. Enter a “Magnitude” of 1MPa.
b.
a. c. d.
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. . . Preprocessing 13. Apply supports to constrain the part:
a. Select “Insert Supports” from the Wizard. b. Follow the callout box to insert a “Frictionless Support”. c. “Apply” it to the 4 counter bore surfaces of the part.
a.
b.
c.
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. . . Preprocessing 14. Repeat Steps 13.a. and 13.b. to insert a “Frictionless Support” on the inner surfaces of the bottom recess (use extend to limits after selecting one of the inner surfaces.
15. Repeat Steps 13.a. and 13.b. to insert a “Frictionless Support” on the lip surface at the bottom of the recess.
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. . . Preprocessing 16. From the Me chanical Wizard requ est:
a) Insert Structural Results (the call out will point to the Solution toolbar).
b) Deformation > Total. c) Stress > Equivalent (von-Mises). d) Tools > Stress Tool. c.
b.
d.
a.
Note the Stress Tool detail allows 4 different configurations (explained later). For this workshop we will leave the tool specified as “Max Equivalent Stress” theory. 17
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Solution 17. Solve the model:
a. Select “Solve” from the Wizard. b. Follow the callout box and click on “Solve”.
b.
a.
•
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Note how clicking on “Solve” in the Wizard does not automatically start solving the model but instead, points out the “Solve” icon to the user. Alternatively, you could right click on any branch in the “outline” and choose “Solve”
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Results 18. View the results:
a. Click “View Results” from the Wizard b. Follow the callout box to where the results are available under the “Solution” branch
a.
b.
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. . . Results Plotting a model’s deformation often provides a “reality check” in structural analysis. Verifying the general nature (direction and amount) of deflection can help avoid obvious mistakes in model setup. Animations are often used as well.
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. . . Results After reviewing stress results expand the Stress Tool and plot safety factor. Notice the failure theory selected predicts a minimum safety factor of just over 1.
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Report 19. Create an html report:
a. First choose the graphical items you wish to include in your report and insert a figure for each one (this is your choice).
b. Click the “Report Preview” tab to generate the report.
a.
b. 22
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. . . Report Notes on Figures: Figures are not limited to results items. Adding a plot of the environment branch, for example, will include an image of model boundary conditions in the Report. Figures are independent. You may set up individual figures and have their orientation, zoom level, etc. retained regardless of the active model orientation or other figures. Individual branches can have multiple figures associated with them.
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Workshop 3.1 2D Gear and Rack Analysis 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
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Assumptions Workshop 3.1 consists of a 2 part assembly representing spur and rack gear components from a 2500 N hand press. We will solve it as a 2D plane stress mod el (thickness = 12 mm).
2D Plane Stress Full Model
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Model
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Goals Analysis Goals: •
We are designing a press that should be capable of delivering 2500 N of force in the rack.
•
In order to design the mechanism for applying the load we need to know the required torque in the gear to produce the necessary force.
•
We’ll apply the desired force in the rack and extract the moment reaction at the gear.
•
We will use a “Remote Displacement” to constrain the gear (instead of a fixed support) because this type of constraint provides rotational, as well as translational, constraints.
Remote Displacement
Force = 2500 N 3
© 2012 ANSYS, Inc.
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Units Open the Project page. From the Units menu verify: •
Project units are set to “Metric (kg, mm, s, C, mA, mV).
•
“Display Values in Project Units” is checked (on).
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Project Schematic 1. Double click “Static Structural” analysis type to add a new system.
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2. RMB the Geometry cell and request “Properties”.
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. . . Project Schematic 3. In the “Analysis Type” field specify “2D”. •
Once this setting is made the properties window may be closed if desired.
Note this setting indicates the model to be analyzed is not a full 3D model but represents a symmetry section. It is important that this is set prior to importing geometry as this setting cannot be changed after the import.
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Geometry Setup 4.
From the “Geometry” cell, RMB > “Import Geometry” and browse to: “Gear_Set_2D.stp”. 4.
5.
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Double click the “Model” cell to start Mechanical.
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Preprocessing 6.
Set the working unit system: a. “Units > Metric (mm, kg, N, s, mV, mA)”. 6a.
7.
Set the Plane Stress options:
a. Highlight the “Geometry” branch. b. Verify the “2D Behavior” to be “Plane Stress”
7a.
(default).
7b.
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Preprocessing 8.
8a.
Set the geometry thickness: a. Highlight the Gear and Rack parts (use shift or control for multi-select). b. Set the thickness field to 12 m m. 8b.
9a.
9. Set the c ontact options:
a. Highlight the contact branch branch. b. Change the contact type to “No Separation”.
9b.
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Preprocessing 10. Create a r emote point: 10a.
a. Highlight the Model branch. b. Set the selection filter to “edge select”.
10b.
c. Select the circular inner edge of the gear. d. RMB > I nsert > Remote Point.
10d. 10c.
Note the annotation flag indicating the remote point location.
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Environment 11. Apply remote di splacement on the m odel:
a. Highlight the Static Structural branch. b. “RMB > Insert > Remote Displacement”. c. Change the scoping method to “Remote Point”. d. Select “Remote Point” from the RP list e. Set X, Y and Rotation Z = 0.
11a.
11c. 11d.
11b.
11e.
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…Environment 12. Apply frictionless support to the mo del:
a. Highlight the right edge of the rack. b. “RMB > Insert > Frictionless Support”. 12a.
12b.
We use a frictionless support along the edge of the rack to simulate the guide the part rides in.
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…Environment 13. Apply a force to the model:
a. Select the bottom edge of the Rack. b. “RMB > Insert > Force”. c. Change to the component method. d. Input a Y component = 2500 N. 13c.
13d.
13b.
13a.
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Solution 14. Solve the m odel.
15. Insert a Total Deformation result: a. Highlight th e So lution branch. b. RMB > Ins ert > To tal De formation. c. RMB > Ev aluate All Results.
14.
15a.
15b.
15c.
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…Postprocessing 16. Extract the mo ment reaction in th e gear:
16a.
a. Highlight the Sol ution branch. b. From the context menu choose “Probe > Moment Reaction”. c. In the probe details choose “Remote Displacement” from the drop down list. d. RMB > E valuate All Results.
16c.
16d.
16b.
Moment reaction about Z axis
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© 2012 ANSYS, Inc.
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Conclusion Our stated goal was to determine the required moment that must be applied to the gear in order to produce a 2500 N force in the rack. We conclude a torque of approximately 92,000 N*mm will be required.
- 92,000 N*mm
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Workshop 3.2 Named Selections 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals The goal of this workshop is to use several techniques to create named selections that will then be used to set up the boundary conditions shown below.
2
•
Two holes at one end of the model will be used to apply a fixed support.
•
On one of the remaining holes we will apply a radial displacement to simulate the effect of a fastener that has been press fit into it.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Begin a new Workbench session and, from the Project page, choose “Restore Archive . . . “ and browse to the file “Named_Selections.wbpz” and Open (location provided by instructor). When prompted, “Save” using the default name in the same location as the archive file.
From the “Units” menu verify: •
Project units are set to “Metric (kg, mm, s, ºC, mA, N, mV).
•
“Display Values in Project Units” is checked (on).
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. . . Project Schematic 1. From the S tatic Structural system double click (or RMB > Edit) the “Model” cell.
1.
2. When Mechanical opens, verify the units are set to “Metric (mm, kg, s, mV, mA)”.
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Preprocessing When Mechanical opens note the model’s orientation with respect to the global coordinate system: 3. Expand the Coordinate Systems branch and highlight “Global Coordinate System”.
3.
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. . . Preprocessing The first named selection will be created so that the constraints can be added to the geometry and conveniently modified. 4.
Highlight the cy lindrical fa ce of t he h ole nearest the global coordinate system srcin.
5.
RMB > Create Named Selection.
4.
5. 6
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. . . Preprocessing 6.
In the Selection dialog enter t he name “Fixture”.
6. 7.
7.
Choose “Apply geometry items of same:”.
8.
Check the box “Size”.
9.
In the tree, highlight the new named selection “Fixture” and note the scope of the selection is 4 faces.
8.
9.
Since our goal is to apply the constraints only to the 2 holes closest to the srcin, we need to add a location filter the worksheet.
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. . . Preprocessing In order to proceed we need to first determine the location of the features to be filtered. While there are a number of ways we might accomplish this, we’ll use the “selection information” feature. 10. Highlight the cylindrical face used previously.
10.
11. In the top menu click the box to activate “Selection Information”. 11.
The summary shows the face centroid is located at an X coordinate of 8 mm. Also note the radius of the cylinder is 2.5 mm.
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. . . Preprocessing In the worksheet shows the initial selection (select by size) is represented by the first row. 12. RMB in the worksheet and “Add Row”.
12. By inspection we can see that the centroid of both required holes must be at the same X location. Instead of using that criteria directly we’ll illustrate the use of a “filter”. 13. Configure the row to filter the selection based on X location in a range of 0 to 10 mm. 14. “Generate”.
14. 13. 9
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. . . Preprocessing 15. With the filter applied verify the scope of the selection is now 2 faces. 15.
16. In the graphics window review the selection.
16.
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. . . Preprocessing Again, there are a number of ways we might proceed with this step, but we’ll create a geometry based named selection and then convert it to a mesh based selection. Create a named selection where the press fit simulation will be applied: 17. Select the cylindrical face shown here. 18. RMB > Insert > Named Selection.
17.
19. In the tree RMB > Rename the new selection to “PressFace”. 18.
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. . . Preprocessing 20. Highlight the Named Selections branch, “RMB > Insert > Named Selection”. 20.
21. In the details for the new selection change the scoping method to
21.
22. In the worksheet RMB > Add Row and configure to add a face named selection, equal to “PressFace”.
22.
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. . . Preprocessing 23. In the worksheet RMB > Add Ro w and configure to convert to mesh nodes. 24.
23.
24. Generate the named selection.
25. In the tree, rename the selection to “PressNodes”.
25.
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. . . Preprocessing 26. Review the details and the graphics window (using the “Graphics” tab at the bottom of the worksheet), and note that we now have a named selection composed of 88 nodes associated with the desired face.
26.
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. . . Preprocessing As stated earlier we wish to simulate a press fit by displacing the nodes in the cylinder in a radial direction. We need a local cylindrical coordinate system to use as a reference. 27. Highlight the same face used t o create the previous named selection, RMB > Insert > Coordinate System. 27.
28. In the new c oordinate system details change the type to Cylindrical. 29.
29. Rename the new coordinate system “PressSystem”.
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28.
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Environment 30. Highlight the Static Structural branch, RMB > Insert > Fixed Support. 30.
31. In the details change the scoping method to “Named Selection”. 32. From the drop down list choose the named selection “Fixture”.
31. 32.
In the graphics window note the fixed support is scoped to the 2 holes closest to the global srcin.
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. . . Environment Before proceeding with the next step (applying the radial displacement to the nodes) it will be useful to review the basics of nodal loads (covered in Mechanical Intro Part 1). Recall: •
•
Nodal loads are applied to a nodal named selection. The directions in which nodal loads are applied, unlike their loads, are always with respect to each node’s individual coordinate system.
Because of this second point nodal orientations must sometimes be modified so that the correct load direction can be defined.
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. . . Environment 33. Highlight the Static Structural branch, RMB > Insert > Nod al Orientation.
33.
34. In the nodal orientation details for “Named Selection” choose “PressNodes” from the drop down list. 35. In the detail for “Coordinate System” choose “PressSystem” (defined earlier).
34. 35. 18
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. . . Environment 36. Highlight the Static Structural branch, RMB > Insert > FE Displacement.
37. In the FE Displacement details for “Named
36.
Selection” down list. choose “PressNodes” from the drop 38. Enter a value of 0.1 mm in the X component field. Recall that the earlier nodal rotation was done with respect to a local cylindrical system. For cylindrical systems the X, Y and Z directions are interpreted as radial (X), tangential (Y) and axial (Z) directions.
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37.
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Postprocessing Solve the model.
When the solution is complete various displacement plots can be used to verify the loading. In the figure on the right a directional deformation result is transformed into the local cylindrical system (PressSystem) defined earlier.
Total Deformation
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Transformed Deformation
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. . . Postprocessing A final verification can be done by plotting the Nodal Triads associated with each node. To create a clearer display, the coordinate display was scoped only to the face where the displacement is applied.
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Workshop 3.3 Object Generator 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals Workshop 3-3 consists of 2 plates separated by 45 mm. Each plate contains 12 holes which are to be connected using beam connections. Instead of creating 12 individual beam connections we’ll create a single beam and u se the Object Generator in Mechanical to create the remainder.
55 mm
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Assumptions We’ll assume that one of the plates is fixed around its edges.
The plates will be joined using the Body to Body bolt feature. A force load (1000 N) will be applied to the top surface of one of the plates.
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Project Schematic Open the Project page. From the Units menu verify: •
Project units are set to “Metric (kg, mm, s, C, mA, mV)”.
•
“Display Values in Project Units” is checked (on).
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. . . Project Schematic 1. From the Toolbox insert a “Static Structural” system into the Project Schematic.
1.
2. From t he G eometry cell, RMB an d “Import Geometry > Browse”. Import the file “Bolt_Plates.stp”. 2.
3. Double click the “Model” cell to st art the Mechanical application.
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Preprocessing 4. Set the working unit system: •
“Units > Metric (mm, kg, N, s, mV, mA)”. 4.
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. . . Preprocessing 5.
5a.
Create 2 Named Selections:
a. Select a face on one of th e holes in either plate (which hole or plate is arbitrary).
b. c. d. e.
RMB > Create Named Selection. In the dialog box enter the name “TopHoles” Set “Apply geometry items of same: Size”.
OK 5c. 5b. 5d.
5e. 7
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. . . Preprocessing 6.
Modify the Named Selection:
a. Highlight the “TopHoles” named selection branch. b. In the worksheet RMB > Add Row.
6a.
6b.
c. Configure the new row as shown below. d. Generate 6d.
6c. 8
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. . . Preprocessing The result of the configuration can be seen in the figure on the right. We chose to remove the faces located less than zero which resulted in the holes in the bottom plate being removed from the NS (note the global coordinate system).
7.
Create a second Named Selection:
a. Highlight the “TopHole” NS. b. RMB > Duplicate. c. Rename the new NS “BottomHoles”.
7a.
7c. 7b. 9
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. . . Preprocessing 8. Modify the “BottomHole” NS: a. Change the operator field from “Less Than” to “Greater Than”. b. Generate. 8b.
8a.
As shown here, this single modification reverses the selection set to only those faces in the bottom plate.
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Environment 9.
Create a Beam Connection:
a. Highlight the Connections branch. b. Hold the CTRL key and select 2 opposing
9a.
holes, one from each plate. Again the actual pair of holes selected is arbitrary.
9b.
c. RMB > Insert > Beam. d. In the beam details enter a radius of 2 mm.
9c.
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Release 14.5
. . . Environment 10. Apply the fixed sup port to the mount:
a. Highlight the beam branch under Connections. b. Toggle on the Object Generator icon.
10a.
10b.
Configure the Object Generator as shown here: The “Reference” and “Mobile” fields allow access to the Named Selections created earlier. Since we know the outer distance between the plates is 55 mm, we enter 45 and 55 for min/max distances. Since our named selections are defined between all 12 holes we leave “Ignore Original” checked so the existing beam is not duplicated. 11.
11. Generate. 12
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Solution Graphically all 12 beam connections can be seen. A check of the connections branch verifies this.
Next we’ll apply some simple boundary conditions, solve the model and see how the beam probe can be used to extract the reactions seen by the beams.
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Postprocessing 12. Add a fixed constraint to the bottom plate:
12a.
a. Highlight the Static Structural branch: b. Select one of the side faces on the bottom plate. c. Choose “Extend to Limits” (status bar should indicate 4 faces selected).
d. RMB > Insert > Fixed Support.
12b.
12c.
12d.
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Postprocessing 13. Add a p ressure load to the top plate:
a. b. c. d.
13a.
Highlight the top face of the top plate. RMB > Insert > Force. Change “Define By” to “Components.
Enter 1000 N for the Z component in the force details.
13b.
14. Solve
14.
13c.
13d. 15
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. . . Postprocessing Insert Total Deformation and Equivalent Stress results and evaluate. The plots would indicate that the solution progressed as expected and we can now look more closely at the beam connections.
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. . . Postprocessing 14. Verify the overall reaction force in the model: a.
Drag & Drop the “Fixed Support” in the tree onto the Solution branch.
b.
RMB > Evaluate All Results to calculate the “Force Reaction” result object.
14a.
14b.
A check of the details for the force reaction indicates we have a force balance in the solution.
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. . . Postprocessing 15. Retrieve beam probe results:
a. Drag & Drop the 12 branches representing the circular beams (use Shift key to multi-select).
b. RMB > Evaluate All Results.
15a.
15b.
As the details from one of the beam probes shows there are a number of quantities returned for each beam. Our goal is to verify the axial forces in the beams so we’ll reconfigure the probes. 18
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. . . Postprocessing 16. Modify the beam probes to retrieve only axial results:
a. Highlight all the beam probes in the Solution branch (use Shift key to multi-select).
16a.
b. In the details set the “Result Selection” field to “Axial Force”.
c. “Evaluate All Results”.
Results now show only the axial forces are returned to the beam probes.
16b.
16c.
19
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing •
•
•
•
20
A convenient way to combine all the probe results in one location is to use the chart/table feature and export the data to a spreadsheet. Since not all training machines may have Microsoft Excel installed we’ll simply describe the procedure here.
First highlight all the beam probes in the tree. Then select the Chart/Table icon from the toolbar. A new chart object is displayed in the tree. Notice the details in this case, indicate the chart relates to 12 objects.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing A closer look at the table area shows each of the axial force values from the beam probes is shown in individual columns.
•
•
21
Clicking in the “Steps” column selects the entire row of data and a RMB will allow an “Export” of the data (*.xls or *.txt formats).
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing •
•
22
As shown below a simple summation formula in Excel verifies the combined values for all beam connections.
This workshop has shown how the object generator can be used to create multiple beam connections. The object generator can be used for essentially any object in the tree that allows duplication (e.g. RMB > Duplicate).
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Workshop 4.2 Meshing Control 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals Use the various ANSYS Mechanical mesh controls to enhance the mesh for the model below. Problem statement: •
The model consists of a CAD file representing a solenoid.
•
Our goal is to mesh the model using all defaults and inspect the result. Next we will add mesh controls to modify the mesh in various regions of the model.
2
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Assumptions Since this is a meshing exercise we will not be applying loads or solving the model. Instead we will assume a linear static structural analysis is to follow the meshing operation.
Note, due to a certain randomness in the nature of meshing, the actual number of elements generated during the workshop may vary from machine to machine. This is normal.
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Units Open the Project page. From the “Units” menu verify: •
Project units are set to “US Customary (lbm, in, s, F, A, lbf, V).
•
“Display Values in Project Units” is checked (on).
4
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic 1. In the Toolbox, double click “Static Structural” to create a new analysis system. 1.
2.
2. RMB on the “Geometry” cell and “Import Geometry”. Browse to “Solenoid_Body.stp”. 3.
3. Double click the “Model” cell to start the Mechanical application. 5
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Basic Meshing Start by meshing the model using all defaults. This will establish a “base line” from which we can compare changes.
4.
Highlight the mesh branch, “RMB > Generate Mesh”.
4.
When mesh generation completes we can view the mesh and inspect the statistics in the details for the mesh branch. Note: node/element count may vary slightly across machines/platforms.
6
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Basic Meshing 5.
View the mesh metrics: a.
Highlight the mesh branch.
5a.
b. In the details under “Statistics > Mesh Metric” specify “Element Quality”. 5b.
7
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Mesh Size Control Based on our inspection we may decide a more refined mesh is necessary for our analysis. 6.
In the mesh branch details expand the “sizing” section and set the “Relevance Center” to “Medium.
7.
RMB the mesh branch and Generate Mesh.
The finer mesh is visually obvious. The details show an increase in the number of elements as expected.
8
© 2012 ANSYS, Inc.
December 19, 2012
6.
7.
Release 14.5
Mesh Shape Control A closer look at the mesh shows some anomalies where certain faces meet. By zooming to the area in question we can see several small “sliver” surfaces are forcing a fine mesh locally. We’ll attempt to clean this up using virtual topology.
9
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Virtual Topology 8.
Highlight the Model branch > RMB > Insert > Virtual Topology.
Since it appears that the sliver area is closer to being tangent to the sides, we will combine these into virtual cells.
8.
Sliver Side
10
© 2012 ANSYS, Inc.
In order to preserve the basic topology we will join pairs of surfaces into virtual cells rather than trying to combine all surfaces together. The result will be 3 cells per side, 6 in total.
December 19, 2012
Release 14.5
. . . Virtual Topology 9.
Create V irtual Cells:
9b.
9a.
a. Select one of the sliver surfaces. b. Hold the CTRL key and select the adjacent surface (as shown at right).
c. RMB > Insert > Virtual Cell. 9c.
The resulting virtual cell is displayed in red. Although underlying surfaces still exist, this is the surface the mesher will use.
11
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Virtual Topology Continue by creating the remaining 5 virtual cells (select in pairs as before). When complete you will have a total of 6 virtual faces and 4 virtual edges.
Remesh the model:
10.Highlight the Mesh branch, RMB > Generate Mesh.
10.
The resulting mesh shows a much more uniform mesh with a significant reduction in element count.
12
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Mapped Face Meshing 11. Map mesh se veral faces (h ighlight Mesh branch):
a. Select the 3 planar faces shown here. b. RMB > Insert > Mapped Face Meshing. c. RMB > Generate Mesh. 11a.
As shown map meshing results is elements on the selected faces which share very regular shapes.
11b.
11c.
13
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Face Size Control 12. Specify face sizi ng on s elected face:
a. Select the face of the gusset section shown here. 12a.
b. RMB > Insert > Sizing. c. Set Element Size = 0.03. d. Set Behavior = “Hard”.
12b.
13. Remesh the model (highlight the mesh branch): •
RMB > Generate Mesh.
13.
12c. 12d.
14
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Edge Size Control 14. Specify edge sizi ng on s elected edges:
a. b. c. d. e.
Select the 4 edges of the gusset shown here.
14a.
RMB > Insert > Sizing. Change “Type” to “Number of Divisions”. Set Number of Divisions = 25. Set Behavior = “Hard”.
15. Remesh the model (highlight the mesh branch): •
14b.
RMB > Generate Mesh.
15.
14c. 14d. 14e. 15
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Edge Size Control Review the mesh metric as compared to the srcinal mesh. With just a few refinements overall mesh quality has improved.
Original Mesh Metric
Final Mesh Metric
16
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Workshop 5.1 Linear Structural Analysis 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals Workshop 4 consists of a 5 part assembly representing an impeller type pump. Our primary goals are to analyze the assembly with a preload on the belt of 100N to test: • •
2
That the impeller will not deflect more than 0.075mm with the applied load. That the use of a plastic pump housing will not exceed the material’s elastic limits around the shaft bore.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Assumptions We’ll assume the pump housing is rigidly mounted to the rest of the pump assembly. To simulate this, a frictionless support is applied to the mounting face.
Similarly, frictionless surfaces on the mounting hole counter bores will be used to simulate the mounting bolt contacts. (Note if accurate stresses were desired at the mounting holes, a “compression only” support would be a better choice). Finally, a bearing load (X = 100 N) is used on the pulley to simulate the load from the drive belt. The bearing load will distribute the force over the face of the pulley only where the belt contact occurs.
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Open the Project page. From the Units menu verify: •
Project units are set to “Metric (kg, mm, s, C, mA, mV)”.
•
“Display Values in Project Units” is checked (on).
4
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Project Schematic 1. From the Toolbox insert a “Static Structural” system into the Project Schematic.
1.
2. From t he G eometry cell, RMB an d “Import Geometry > Browse”. Import the file “Pump_assy_3.stp”. 2.
3. Double click the “Model” cell to st art the Mechanical application.
5
© 2012 ANSYS, Inc.
December 19, 2012
3.
Release 14.5
Preprocessing 4. Set the working unit system: •
“Units > Metric (mm, kg, N, s, mV, mA)”.
5. Add “Polyethylene” the Engineering Data (return to Workbench window):
4.
a. Double click the Engineering Data cell. b. Activate the Data Source toggle and highlight General Materials and click the + sign next to “Polyethylene”.
c. Return to Project.
5a.
5b.
6
© 2012 ANSYS, Inc.
December 19, 2012
5c.
Release 14.5
. . . Preprocessing 6. Refresh the Model cell:
a. RMB > Refresh. 6a.
Return to the Mechanical window.
7. Change the material on the pump housing:
a. Highlight “PumpHousing” under geometry. b. From details change the material assignment to “Polyethylene”.
7
© 2012 ANSYS, Inc.
December 19, 2012
7a.
7b.
Release 14.5
. . . Preprocessing 8. Change the contact region behavior for the f irst 4 contact regions (shown below):
a. Hold the shift key and highlight the first 4 contact branches.
8a.
b. From the detail window change the contact type to “no separation”. •
The remainder of the contacts will be left as “bonded”.
8b.
8
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Environment 9. Apply the bearing load to the pulley:
a. b. c. d.
Highlight the “Static Structural” branch. Highlight the pulley’s groove surface. RMB > Insert > Bearing Load”. From the detail window change to “Components” and “X = 100 N”
9a.
9b. 9c. 9d.
9
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Environment 10. Apply supports to the assembly:
a. Highlight the mating face on the pump housing (part 1). b. “RMB > Insert > Frictionless Support”.
10a.
10b.
10
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Environment Now we will add the frictionless supports to the 8 countersink portions of the mounting holes (shown here). Each of the required surfaces could be selected individually while holding the CTRL key however we will use a macro (select by size) provided with Mechanical. After selecting the initial surface, running the macro finds and selects all surfaces of the same size (area). Note, this macro also works with edges or bodies.
11
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Environment 11. Select the countersunk holes (select by size macro):
a. Highlight 1 of the countersink surfaces (arbitrary). b. Choose “Tools > Run Macro . . .” and browse to:
11a.
C:\Program Files\ANSYSInc\v140\AISOL\DesignSpace\DSPages\macros
c. In the browser choose “selectBySize.js” d. Click “Open” 11c. 11b.
11d.
12
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Environment Constrain the countersunk hole surfaces:
12. From the context menu, click on “Supports” and choose “Frictionless Support” or “RMB > Insert > Frictionless Support”
13
© 2012 ANSYS, Inc.
December 19, 2012
12.
Release 14.5
Solution 13. Highlight the “Analysis Settings” and from the details window change “Weak Springs” from “Program Controlled” to “Off”.
13.
Note : Because of the presence of frictionless supports and non bonded contact, Workbench-Mechanical will trigger the use of weak springs during the solution. If we know the model is fully constrained we can turn off this function.
14. Solve the model: •
14
Choose solve from the tool bar or RMB Solution branch and choose “Solve”.
© 2012 ANSYS, Inc.
December 19, 2012
14.
Release 14.5
Postprocessing 15. Add results to solution:
a. Highlight the solution branch: b. From the context menu, choose Stresses > Equivalent (von-Mises) or RMB > Insert > Stress > Equivalent (von-Mises)
c. Repeat the step above, choose Deformation > “Total Deformation” •
Solve again. •
Note: adding results and re-solving the model will not cause a complete solution to take place. Requesting new results requires only a re-read of the results file.
15b.
15c.
15a. 15
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing While the overall plots can be used as a reality check to verify our loads, the plots are less than ideal since much of the model is displayed in few colors. (your results may vary slightly due to meshing differences).
To improve the quality of results available we will “scope” results to individual parts”. 16
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing 16. Scope the results to individ ual bodies/surfaces:
a. Highlight the “Solution” branch and switch t he
16a.
selection filter to “Body” select mode.
b. Select the impeller (part 2) c. “RMB > Insert > Stress > equivalent (von- Mises)” •
16b.
Notice the detail for the new result indicates a scope of 1 Body.
17. Repeat the procedure above to insert “Total Deformation” results for the impeller part.
16c.
18. Repeat to add individ ually scoped stress and total deformation results to the pump housing (part 1).
17
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing 19. Rename the new results:
a. RMB on the result > Rename b. Rename the results as shown here to simp lify postprocessing
19b. 19a.
20. Solve
18
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing By checking the impeller deformation we can verify that one of our goals is met. The maximum deformation is approximately 0.024mm (goal < 0.075mm).
19
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing Inspection of the housing stress shows that, overall, the stress levels are below the material’s elastic limit (tensile yield = 25 MPa). We could again use scoping to isolate the results in the area of interest.
20
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Workshop 5.2 Beam Connections 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals Workshop 5-2 consists of a flange containing 2 parts. The fasteners holding the flange together are not modeled. Instead we’ll use Mechanical’s beam feature to simulate them. We’ll then use a remote force to represent a structural load whose line of action is located some distance from the flange.
2
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Assumptions We’ll assume the mount is fixed to some larger assembly. As noted, we’ll use the Body to Body bolt feature to simulate the fasteners. Finally, a remote load (X = 1000 N) scoped to the flange face and located at Z = 100 mm..
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Open the Project page. From the Units menu verify: •
Project units are set to “Metric (kg, mm, s, C, mA, mV)”.
•
“Display Values in Project Units” is checked (on).
4
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Project Schematic 1.
From the Toolbox insert a “Static Structural” system into the Project Schematic.
1.
2.
From the Geometry cell, RMB and “Import Geometry > Browse”. Import the file “Flange Mount.stp”. 2.
3.
5
Double click the “Model” cell to st art the Mechanical application.
© 2012 ANSYS, Inc.
December 19, 2012
3.
Release 14.5
Preprocessing 4. Set the working unit system: •
“Units > Metric (mm, kg, N, s, mV, mA)”. 4.
6
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 5.
Change t he c ontact region b ehavior:
a. Highlight the contact branches. b. From the detail window change the contact type to “frictionless”.
5a.
Note: frictionless contact is nonlinear. We are using frictionless contact because this behavior allows separation.
5b.
7
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 6.
Add b eams to model fasteners:
a. Highlight the connections branches. b. From the connections context menu choose
6a.
“Body-Body > Beam”.
Mobile
The scope of the bolted connections is shown here for clarity. The next several slides describe the procedure.
Reference 8
© 2012 ANSYS, Inc.
December 19, 2012
6b. Release 14.5
. . . Preprocessing 7.
Add beam details:
a. Enter “5” mm for beam radius. –
Note, structural steel is the assumed material
b. Scope the Reference side of the beam as shown.
7a.
7b.
c. Scope the Mobile side of the beam as shown. 7c.
Note: the designation of which face is to be reference or mobile is arbitrary in this case. 9
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 8. Change beam behavior:
a. Change the reference behavior to “Deformable”. 8a.
b. Change the mobile behavior to “Deformable”. 8b.
Repeat steps 6 through 8 for the remaining three holes.
10
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Environment 9.
9b.
Add a remote force:
a. Highlight “Static Structural” in the tree.
9a.
b. Select the flange face shown. c. RMB > Insert > Remote Force.
9c. 9d.
d. Set the location to 0, 0, 100 as shown. 9e.
e. Switch to the component method and enter X component = 1000 N.
11
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Environment 10. Apply the fixed sup port to the mount:
a. Highlight the “Static Structural” branch. b. Highlight the mount surface shown. c. RMB > Insert > Fixed Support.
10a.
10b. 10c.
12
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Solution 11. Highlight the “Analysis Settings” and from the details window change “Weak Springs” from “Program Controlled” to “Off”.
11.
Note : Because of the presence of frictionless contact Workbench-Mechanical will trigger the use of weak springs during the solution. If we know the model is fully constrained we can turn off this function.
12. Solve th e mo del: •
13
Choose solve from the tool bar or RMB in the tree and choose “Solve”.
© 2012 ANSYS, Inc.
December 19, 2012
12.
Release 14.5
Postprocessing 13. Add results to solution:
a. Highlight the solution branch: b. From the context menu, choose Stresses > Equivalent (von-Mises) or RMB > Insert > Stress > Equivalent (von-Mises)
c. Repeat the step above, choose Deformation > “Total Deformation” 14. Solve again. •
Note: adding results and re-solving the model will not cause a complete solution to take place. Requesting new results requires only a re-read of the results file.
13b.
13c.
13a.
14
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing For beam connections, no contours are displayed however results can be obtained using a Beam Probe (see step 15).
Beam Connections
15
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing By turning on Auto Scale from the context menu (magnifying displacements) you can see the tendency for the flange to separate due to the remote force.
16
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing 15. Retrieve results for beams:
a. Highlight the 4 branches representing the circular
15a.
beams.
b. Drag and drop the beams on to the Solution branch. c. RMB > Evaluate All Results.
15b.
A sample of one of the details windows for the beam sections shown here displays the various results available
17
© 2012 ANSYS, Inc.
December 19, 2012
15c.
Release 14.5
. . . Postprocessing 16. Review F E Co nnections:
a. Highlight the Solution Information Branch. b. In the “FE Connection Visibility” section set “Display”
16a.
to “All FE Connectors”.
c. At the bottom of the graphics window change to the Graphics tab.
16c.
18
© 2012 ANSYS, Inc.
16b.
December 19, 2012
Release 14.5
. . . Postprocessing •
•
19
The figure on the left shows all constraint equations written as a result of the remote force and the beam connections. On the right the beam connections are shown.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Workshop 6.1 Contact Offset Control 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals Problem statement: •
The model consists of a workbench archive file representing a valve and piston assembly with loads applied (see figure on left).
•
As the figure on the right shows, a gap exists between the piston and bore (0.39 mm).
•
Our goal is to: –
Solve the model as is with no interface treatment (results will be non physical).
–
Solve the model a second time using an appropriate initial contact offset to close the gap.
2
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Begin a new Workbench session and, from the Project page, choose “Restore Archive . . . “ and browse to the file “Contact_Interface.wbpz” and Open (location provided by instructor). When prompted, “Save” using the default name and the same location.
From the “Units” menu verify: •
Project units are set to “Metric (kg, mm, s, ºC, mA, N, mV).
•
“Display Values in Project Units” is checked (on).
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Project Schematic 1.
From th e St atic S tructural system d ouble click (or RMB > Edit) the “Model” cell.
1.
2.
4
When Mechanical opens, verify th e un its are set to “Metric (mm, kg, s, mV, mA)”.
© 2012 ANSYS, Inc.
December 19, 2012
2.
Release 14.5
Preprocessing 3. Verify the boundary conditions are set as described here: •
Force (20N in +Y) applied to the end of the piston shaft.
•
Fixed supports applied to the 4 holes in t he valve.
•
Remote displacement applied to the inside face of the piston: – –
5
X=0
–
Y = Free Z=0
–
RotX = 0
–
RotY = 0
–
RotZ = Free
© 2012 ANSYS, Inc.
3.
December 19, 2012
Release 14.5
. . . Preprocessing 4. Check the current contact settings: •
•
•
Notice the contact type is frictionless and that no offset has been specified in the form of an interface treatment. All other settings are left as default.
Recall that a 0.39 mm gap exists between the piston and valve. With the boundary conditions as set, we should expect the piston to be initially free as the force is applied.
4.
0.39 mm Gap
6
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Solution 5.
•
•
•
7
Solve the model:
5.
When the solution completes a message should indicate possible rigid body motion has occurred. A quick check of the magnitude of total deformation should confirm the message. A magnified deformation shows the 2 parts have separated as expected.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Background Background: how would we find the size of the gap?
•
•
•
8
One method is to select the circular lines for the piston and the bore and request the “Selection Information”.
From the information panel we can see 8 .89 – 8.5 = 0.39 mm gap.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Background Background: how would we find the size of the gap?
•
•
•
9
A second method is to insert the Contact Tool at the Connections branch and “Generate Initial Contact Results”.
The initial information shows a Gap of 0.3851 mm.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Preprocessing To address the gap in the contact return to the contact details: 6.
In the “Offset” field enter 0.39. •
7.
Verify the Interface Treatment is set to “Add Offset, No Ramping”.
Re-solve t he m odel. •
The model should solve in se veral iterations. 7. 6.
10
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Postprocessing 8.
The deformation and stress results now appear to be reasonable.
Total Deformation
11
© 2012 ANSYS, Inc.
December 19, 2012
Equivalent Stress on the valve
Release 14.5
. . . Postprocessing 9.
Insert th e Contact To ol into the So lution branch. •
12
Check the Contact Status to verify contact has been maintained.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Conclusions Notes: •
•
•
13
The initial solution verified that rigid body motion was occurring when we tried to apply a force to parts which were separated by an initial gap. We were able to determine the gap size using 2 different methods in order to determine how to address the contact problem. With the gap size verified, we input an initial offset at the contact, effectively closing the gap.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Workshop 6.2 Using Joints 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals The goal of this workshop is to use joints to connect some parts in an assembly instead of contact. Joints can provide a convenient alternative to contact.
The 4 part assembly shown here would normally be connected using contact definitions. In this workshop the model contains a single contact region. We’ll use the automatic joint feature to setup the remainder of the connections and make several modifications before solving.
2
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Begin a new Workbench session and, from the Project page, choose “Restore Archive . . . “ and browse to the file “Joint_Connection.wbpz” and Open (location provided by instructor). When prompted, “Save” using the default name in the same location as the archive file.
From the “Units” menu verify: •
Project units are set to “Metric (kg, mm, s, ºC, mA, N, mV).
•
“Display Values in Project Units” is checked (on).
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Project Schematic 1. From the S tatic Structural system double click (or RMB > Edit) the “Model” cell.
1.
2. When Mechanical opens, verify the units are set to “Metric (mm, kg, s, mV, mA)”.
4
© 2012 ANSYS, Inc.
December 19, 2012
2.
Release 14.5
Preprocessing 3. Highlight the Connections branch. Notice that currently there is a bonded contact region between the Piston and Pin parts.
3.
4. From the Connections branch, RMB > Insert > Connection Group.
4.
5. In the connection group details change the connection type to “Joint”. 5.
5
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 6.
Highlight the “Joints” branch, RMB > Create Automatic Connections”. 6.
You should see 4 new joints have been created. Before inspecting the joints, we’ll rename them to make the process easier. 7.
7.
6
Highlight the Joints branch, RMB > Rename Based on Definition.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 8.
Highlight the “Crank To Con_Rod” joint.
8.
– A revolute joint has been defined between the crank and the connecting rod. We’ll keep this as it is.
9.
Highlight the “Con_Rod To Pin” joint. – A revolute joint has been defined here which we will
9.
also keep.
7
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing Highlight the “Pin To Piston” joint. – Notice in the Contacts branch there is a contact region
10.
already defined between these parts (“Bonded – Pin to Piston”). This joint can be deleted.
10. Highlight the joint “Revolute – Pint To Piston” > RMB > Delete.
11. Highlight the “Fixed - Con_Rod To Piston” joint, RMB > Delete the fixed joint. – A fixed joint has been defined between 2 adjacent
11.
faces. This joint is not only unnecessary, it will prevent proper motions in the assembly.
8
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Environment 12. Highlight the Static Structural branch.
12.
13. Highlight the tapered cylindrical face on the crank shown here. 13.
14. RMB > Insert > Fixed Support.
14.
9
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Environment 15. Highlight the cylindrical face on the crank shown here.
15.
16.
16. RMB > I nsert > Cy lindrical Support.
17. In the details configure: •
Radial = Fixed
•
Axial = Free
•
Tangential = Free 17.
10
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Environment 18. Highlight the cylindrical face on the piston shown here.
18.
19. RMB > I nsert > Fr ictionless Support.
20. Highlight the circular top face on the piston shown
19.
here. 21. RMB > In sert > P ressure. 20.
22. In the details enter a Magnitude = 0.5 MPa.
21. 22.
11
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Environment 23. Solve th e mo del.
23.
When the solution completes plot displacement and stress to review. Drag and drop the “Cylindrical Support” and “Fixed Support” onto the Solution branch to obtain the reaction forces.
12
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Environment Let’s review the loading to determine if the forces balance: •
•
Highlighting the top face of the piston shows (in the status bar), the approximate surface area is 9740 mm^2. Applying a 0.5 Mpa pressure should result in an approximate applied force of 4870 N in the –Y direction.
Reviewing the details for the reactions we see: •
Y reaction at the fixed support = 4004 N
•
Y reaction at the cylindrical support = 922 N
•
Total Y reaction (4004 + 922) = 4926
Note, using a default mesh may result in slight differences in your results compared to those here. The difference here, (~56 N) represents approximately a 1% difference. 13
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Workshop 7.1 Remote Boundary Conditions 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals The goal of this workshop is to analyze the base of the ja ck assembly shown here. Our assumption is the mechanism has been proven already so we choose to not include the additional parts and model only the base.
2
•
The weight of a vehicle will be simulated using a point mass.
•
We’ll assume there are lateral loads acting on the jack as well which will be applied using a remote force.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals Since we won’t be modeling the entire assembly, we need to know the location where the jack will be contacting the vehicle. We assume this to be the centroid of the top member of the jack assembly. Centroid = (-2, 247, 0)
247 mm Analysis Model
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Begin a new Workbench session and, from the Project page, choose “Restore Archive . . . “ and browse to the file “Remote_BC.wbpz” and Open (location provided by instructor). When prompted, “Save” using the default name in the same location as the archive file.
From the “Units” menu verify: •
Project units are set to “Metric (kg, mm, s, ºC, mA, N, mV).
•
“Display Values in Project Units” is checked (on).
4
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Project Schematic 1. From the S tatic Structural system double click (or RMB > Edit) the “Model” cell.
1.
2. When Mechanical opens, verify the units are set to “Metric (mm, kg, s, mV, mA)”.
5
© 2012 ANSYS, Inc.
December 19, 2012
2.
Release 14.5
Preprocessing When Mechanical opens we will have only the base part. Since we’ll be using remote conditions as well as a point mass all at the same location, it makes sense to use a remote point as a reference. – Note, the use of a remote point means multiple conditions at the same loction (like point masses, remote loads, etc.), can all reference that location without duplicating the constraint equations used to apply them.
3. 4.
Highlight the Model branch in the tree. Select the 8 split faces shown here, RMB > Insert > Remote Point.
3. 4.
6
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 5.
Highlight the remote point, RMB > Rename: “Load Point”.
6.
In the Remote Point details enter the location:
– X=-2 – Y = 247 – Z=0
5.
6.
As said earlier, this location represents the centroid of the top pad of the jack where the vehicle will make contact when it is lifted.
7
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 7.
Highlight the Geometry branch. 7.
8.
RMB > Insert > Point Mass.
9.
In the poto int“Remote mass detPoint”. ails change the Scoping Method
10. In the Remote Points field choose “Load Point” from the list.
11. Enter a mass of 350 kg in the details.
8
© 2012 ANSYS, Inc.
December 19, 2012
8.
9. 10.
11.
Release 14.5
. . . Preprocessing 12. Highlight the Static Structural branch, RMB > Insert > Remote Force. 12.
13. In the details change the Scoping Method to “Remote Point”. 14. Select “Load Point” from the drop down list of remote points.
13. 14.
15. In the details enter the following loads:
9
•
X Component = 2
•
Y Component = 0
•
Z Component = 4
© 2012 ANSYS, Inc.
December 19, 2012
15.
Release 14.5
. . . Preprocessing 16. Highlight the bottom face of the part, RMB > Insert > Fixed Support.
16.
17. Highlight the Static Structural branch, RMB > Insert > Standard Earth Gravity.
17.
18. Specify –Y direction for gravity.
18.
10
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Postprocessing Solve the model.
When the solution is complete various displacement plots can be used to verify the loading.
In this workshop we’ve shown how remote boundary conditions can be used to simplify the geometry model making for a more efficient solution.
11
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Workshop 7.2 Constraint Equations 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals The model shown represents a hook fastener often used to snap components together in an assembly. The goal of this workshop is construct a constraint equation that will simulate the Y displacements in the hook’s tip as it is pressed into place in the X direction. Only the hook section is modeled. Note, although there are a number of ways this simulation could be set up, the purpose of this workshop is to gain practice with constraint equations. Y
X
2
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Background Using the dimensions shown here we can readily see that a simple relationship exists between the X and Y directions. Specifically, the –Y displacements will be 1/5 of the – X displacements. In other words, when the part has displaced 25 mm in the X direction it will have displaced 5 mm in the Y. Thus:
(1/5)*UX = (UY)
UX = 5*(UY)
0 = 5*(UY) - UX
5 mm
Y X 25 mm
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Begin a new Workbench session and, from the Project page, choose “Restore Archive . . . “ and browse to the file “ConstEqn.wbpz” and Open (location provided by instructor). When prompted, “Save” using the default name in the same location as the archive file.
From the “Units” menu verify: •
Project units are set to “Metric (kg, mm, s, ºC, mA, N, mV).
•
“Display Values in Project Units” is checked (on).
4
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Project Schematic 1. From the S tatic Structural system double click (or RMB > Edit) the “Model” cell.
1.
2. When Mechanical opens, verify the units are set to “Metric (mm, kg, s, mV, mA)”.
5
© 2012 ANSYS, Inc.
December 19, 2012
2.
Release 14.5
Preprocessing Constraint equations are written in terms of remote points. Before we can write the necessary expression we first need to create the remote points. 3.
Highlight the Model branch in the tree.
4.
Highlight the top face of the hook tip (shown here), RMB > Insert > Remote Point.
3.
4.
5.
Right click the new remote point and rename “Tip Point”. 5.
6
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 6.
Highlight the rectangular end of the hook.
7.
RMB > Insert > Remote Point.
6.
7.
8.
Right click the new remote point and rename “Press Point”. 8.
7
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 9.
Highlight the St atic Structural branch, RMB > Insert > Remote Displacement.
9.
10. In the details for the remote displacement change the scope method to “Remote Point”. 11. In the “Remote Points” field choose the point “Press Point”.
10. 11.
8
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 12. In the “Definition” section of the remote point details enter a value of -25 for the X component. In all other fields enter 0. 12.
13. From the Static Structural branch RMB > Insert > Constraint Equation. 13.
9
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 14. In the constraint equation worksheet “RMB > Add” to insert the first row. 14.
15. Referring to the expression from page 5: •
Coefficient = 5
•
Remote Point = “Tip Point”
•
DOF Selection = Y Displacement
15.
16. Add a s econd row and c onfigure as sh own below (coefficient = -1, remote point = “Press Point” and DOF = X displacement).
16. 10
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Solution 17. Highlight the “Analysis Settings” branch. 18. In the details change “Large Deflection” to “On”.
17.
Since we are applying a displacement of 25 mm on the model it means the geometry will change location significantly. The large deflection option instructs the solver to track the change in location of each node. While beyond theinscope of thisMechanical course, theStructural subject is covered in detail the ANSYS Nonlinearities course.
19. Solve.
11
© 2012 ANSYS, Inc.
18.
19.
December 19, 2012
Release 14.5
Postprocessing Viewing deformation in the Y direction can confirm the desired behavior is being simulated. Animation can also provide insight into how the constraint equation is performing.
12
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Solution Note In the workshop we created 2 remote points as a part of the exercise however only one was really necessary. The upper figure shows our srcinal expression. The lower figure is equivalent.
0 = 5*(UY)tippoint – (UX)prespoint
This is equivalent in this case
0 = 5*(UY)tippoint – (UX)tippoint
13
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Workshop 8.1 Multistep Analysis 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals The goal of this workshop is to perform a 3 step analysis on the pipe clamp shown here:
2
•
The bolt will receive a pretension bolt load in LS 1 (locked for LS 2 and 3).
•
The pipe will receive an internal pressure during LS 2.
•
The pipe will receive an axial force load during LS 3.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Begin a new Workbench session and, from the Project page, choose “Restore Archive . . . “ and browse to the file “Pipe_Clamp.wbpz” and Open (location provided by instructor). When prompted, “Save” using the default name and the same location.
From the “Units” menu verify: •
Project units are set to “Metric (kg, mm, s, ºC, mA, N, mV).
•
“Display Values in Project Units” is checked (on).
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Project Schematic 1.
From th e St atic S tructural system d ouble click (or RMB > Edit) the “Model” cell.
1.
2.
4
When Mechanical opens, verify th e un its are set to “Metric (mm, kg, s, mV, mA)”.
© 2012 ANSYS, Inc.
December 19, 2012
2.
Release 14.5
Preprocessing Before we begin preprocessing let’s inspect the model as it is currently set up. 3.
Expand the Connections and Contact branches t o view the contacts. – Browse the 4 contact pairs. They appear to be scoped
3.
correctly but all behavior is currently bonded which we will change (see below).
Contact below the bolt head and between the upper bolt and hole: assumed no separation.
Contact in threaded area: assumed bonded. 5
© 2012 ANSYS, Inc.
December 19, 2012
Contact between the clamp and pipe: assumed bonded. Release 14.5
. . . Preprocessing 4.
Highlight the 1 st and 3d contact regions.
5.
In the details change the “Type” to “No Separation”.
Our assumption of no separation contact means some sliding can occur in those locations. Note, the contact between the clamp and the pipe would normally be frictionless in an application like this. However in the interest of time we wish to avoid doing a nonlinear analysis and only demonstrate multi-step solutions. Thus bonded contact is retained. 6.
5.
6.
Toggle the “Show Mesh” icon to display themesh.
–
6
4.
Notice a body size control has been added to the bolt. As documented, it is recommended that a more refined mesh be used with bolt pretension.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing •
Note toggle off “Show Mesh” before proceeding. 7.
7.
Highlight the Analysis Setting branch.
8.
In the details set Number Of Steps = 3.
9.
Highlight the cy lindrical face o n the bolt, RMB > Insert > Bolt Pretension.
8.
9.
7
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Solution 10. In the tabular data enter a preload of 1 for the first load step (row 1).
10.
11. In rows 2 and 3 change the first column to “Lock”. 11.
•
When complete the table should appear as shown here.
12. Highlight the inner surface of the pipe. 12.
8
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Solution 13. RMB > In sert > Pr essure. 14. In the tabular data enter a value of 0.1 in row 2. – When complete, the table should appear as shown below. Note, the first 2 rows should default to 0 while the 3d row should maintain the load entered.
–
13.
The graph (on left) provides a visual confirmation. 14.
Notice in the table there appears to be a duplication of rows. Why? In nonlinear and transient analyses loads are often ramped from a starting to an ending value. Step 1 appears twice in the table to allow ramping from 0 to 1. In static analysis it is meaningless. 9
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Solution
15.
15. Highlight the end face of t he pipe. 16. RMB > Insert > Force. 17. In the tabular data enter a value of 10 in row 3 (LS 3). •
Note, when complete the table should appear as below. It may be necessary to enter a 0 for LS 2. 16.
17.
10
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Solution 18. Highlight the cylindrical face of the mounting hole.
18.
19. RMB > Insert > Fixed Support.
19.
20. Solve: this will cause all load steps to be solved sequentially. 20.
11
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Background •
12
Note, highlighting the Analysis Settings branch and displaying the legend (RMB > Show Legend). This graphically shows the solution processes. Use the “Visibility” section of the details to further configure the display.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Postprocessing 8.
13
Request deformation and stress plots to review the solutions. Retrieve different time points to see the complete solution.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Workshop 9.1 Free Vibration Analysis 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals Our goal is to investigate the vibration characteristics of the machine frame shown here. We want to solve 2 modal analyses using different mounting points on the frame.
2
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Assumptions The frame contains 8, 20 mm diameter mounting holes. In the first analysis the frame will be constrained by all 8 holes. In the second analysis we’ll only constrain the corner holes. To simplify the setup we’ll create several named selections.
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Units Open the Project page. From the “Units” menu verify: •
Project units are set to “Metric (kg, mm, s, C, mA, N, mV).
•
“Display Values in Project Units” is checked (on ).
4
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic 1. From the Toolbox double click “Modal” to create a new system. 1.
2. RMB the “Geometry” cell and browse to “Machine_Frame.stp”. 3. Double click “Model” to open the Mechanical application. 2. 3.
5
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Setup 4. Set the working Unit System: •
Units > Metric (mm, kg, N, s, mV, mA)
4.
6
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Create Named Selections 5.
Create the first Named Selection: a.
Highlight the Model branch, RMB > Insert > Named Selection.
5a.
b.
In the Named Selection details change the scoping method to “Worksheet”.
5b.
7
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Create Named Selections 6.
Create the first Named Selection: a.
In the Worksheet, RMB > Add Row.
b.
Pick the action “Add” and configure as shown below.
c.
Generate.
d.
Rename to “Eight Holes”.
6a.
6d. 6c.
6b.
Knowing the holes are 20 mm diameter we use the “radius” criteria to create a named selection containing all of the mounting holes.
8
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Create Named Selections 7.
Create a second Named Selection: a.
Highlight the named selection “Eight Holes”, RMB > Duplicate.
b.
Rename the new named selection “Four Holes”.
c.
In the details verify the scoping method is still set to “Worksheet”.
7a.
7b. 7c.
9
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Create Named Selections 8.
Create a second Named Selection: a.
RMB and “Add Row”.
b.
Pick the action “Remove” and configure as shown below.
c.
Generate.
8a.
8c.
8b.
Using the “remove” operation and a range in the X direction we have eliminated the interior holes from the named selection.
10
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Environment 9.
Apply supports to model (highlight the “Modal” branch (A5):
a. From the Supports menu select a “Cylindrical Support”.
9a.
b. Switch the scoping method to “Named Selection”. c. From the named selection list choose “Eight Holes”. d. Change the Tangential setting to “Free”. 9b. 9c.
9d.
11
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Analysis Settings Set Options for Modal Analysis: 10. Highlight “Analysis Settings” to set th e “Max Modes to Find” (defaults to 6 modes).
10.
As a final check verify the status symbols next to the branches. All branches should have either: •
Yellow Lightening bolt (ready to be solved).
•
Green check mark (fully defined).
DO NOT SOLVE YET!
12
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic 11. Add a second modal analysis: •
Return to the Workbench Project, highlight the “Setup” cell, RMB > Duplicate.
11.
The schematic should look like this after duplicating.
13
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Environment 12. Change the supports in the second environment: a.
Highlight the “cylindrical support” in the second environment (Modal (B5)).
12a.
b.
In the details pick the named selection “Four Holes” from the list. 12b.
14
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Environment 13. Solve both environments: a.
Highlight the M odel branch.
b.
RMB > Solve.
13a.
Note, by solving from the Model branch, both environments will be solved.
15
© 2012 ANSYS, Inc.
December 19, 2012
13b.
Release 14.5
Results 14. Select Mode shapes to view (repeat this for both Solution branches):
a. Click on the “Solution” branch. This will display the “Graph” and the “Tabular Data” showing a summary of the frequencies at which the modes occur.
b. In the “Graph” RMB > “Select All” to select all modes. –
Note : This can be done from the “Tabular Data” as well.
c. RMB > “Create Mode Shape Results”. d. Click Solve to view the results.
14d.
14a. 14c. 14b.
16
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Results Comparing the 2 solutions shows very little difference in the 2 environments until the 6th mode.
8 Holes Constrained
4 Holes Constrained
17
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Results Comparing the 6th mode from each solution shows the difference. •
Note: using the viewports “Horizontal Viewports” option you can display both results as shown here.
8 Holes Constrained
4 Holes Constrained
18
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Results 16. Create a histogram to compare the two results: a. Hold the CTRL key a nd highlight both Solution branches. b. Click the “Chart/Table” icon. 16b.
16a.
19
© 2012 ANSYS, Inc.
The chart/table tool provides a convenient method to compare multiple items.
December 19, 2012
Release 14.5
Workshop 10.1 Steady State Thermal Analysis 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals In this workshop we will analyze the pump housing shown below for its heat transfer characteristics. Specifically a plastic and an aluminum version of the housing will be analyzed using the same boundary conditions. Our goal is to compare the thermal results for each configuration.
2
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Assumptions Assumptions: The pump housing is mounted to a pump which is held at a constant 60 C. We assume the mating face on the pump is also held at this temperature. °
The interior surfaces of the pump are held at a constant temperature of 90 C by the fluid. °
The exterior surfaces are modeled using a simplified convection correlation for °
stagnant air at 20 C.
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Open the Project page. From the Units menu verify: •
Project units are set to “Metric (kg, mm, s, C, mA, mV).
•
“Display Values in Project Units” is checked (on).
4
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
… Project Schematic 1. From t he T oolbox, do uble c lick “Steady-State Thermal” to create a new Steady State Thermal system.
1.
2. RMB th e G eometry c ell a nd “Import Geometry” – browse to the file: “Pump_housing.stp”.
5
© 2012 ANSYS, Inc.
December 19, 2012
2.
Release 14.5
… Project Schematic 3. Double click “Engineering Data” and activate the Data Source filter.
3.
4. With “General Materials” highlighted click the ‘+’ next to “Aluminum Alloy” and “Polyethylene” properties to add them to the project.
4.
5. “Return to Project”. 6
© 2012 ANSYS, Inc.
December 19, 2012
5.
Release 14.5
… Project Schematic 6. Double click the “Model” cell to open the Mechanical application. 6.
7. From the Un its menu c hoose/verify: •
“Metric (mm, kg, N, s, mV, mA)”
•
“Celsius (For Metric Systems)” 7.
7
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Preprocessing 8. Change t he material and mesh on the pump housing (part ‘1’):
a. Highlight “1” under geometry. b. From details assign the material
8a.
“polyethylene”.
c. Highlight the Mesh branch and set the mesh relevance = 100.
8b.
8c.
8
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Environment 9. Apply temperatures (highlight the Steady 9a. State Thermal branch):
9b.
a. Select the interior surfaces (13 faces) of the pump housing (hint: use “Extend To Limits” selection feature).
b. RMB > Insert > Temperature. c. Set “Magnitude” field to 90 C. °
d.
Select the m ating surface of t he pump housing. e. “RMB > Insert > Temperature”. f. Set “Magnitude” field to 60 C.
9c.
°
9e.
9d. 9f.
9
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Environment 10. Apply Convection:
10b.
a. Select the exterior (32) surfaces of the pump housing
10a.
(hint: use extend to limits).
b. “RMB > Insert > Convection”. c. In the “Details of Convection” click in the “Film Coefficient” field and choose “Import . . . ”.
Be sure to choose import for co nvections.
d. “Import” the correlation “Stagnant Air – Simplified Case”.
e. Set the “Ambient Temperature” field to 20 C. °
10c. 10d.
10e. 10
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Solution – Model A 11. Solve the model.
11.
12. When the solution is complete insert Temperature and Total Heat Flux results (solve to evaluate results). 12.
Results for polyethylene model.
11
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Model B Setup 13. From the project schematic RMB in the A1 cell and “Duplicate”.
13.
14. Double click the Model branch in the second (B) system.
14.
15. When the new model opens change the material to “Aluminum Alloy” as in step 8. 15.
16. Solve the m odel. 16.
12
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Solution – Model B
Results for aluminum alloy model.
13
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Postprocessing Compare Heat Flux: •
Highlight the “Total Heat Flux” results from e ach model and switch to vector display mode. Activate vector display
Control vector density
Polyethylene
14
© 2012 ANSYS, Inc.
December 19, 2012
Aluminum
Release 14.5
Workshop 11.1 Meshing Evaluation 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals In this workshop an arm from a me chanism will be solved using several different meshes for comparison. Our goal is to explore how meshing changes can have dramatic effects on the quality of the results obtained.
2
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Assumptions In the loading conditions being simulated the arm is experiencing both tensile and bending loads as shown here. Our area of interest is the web section that reinforces the interior of the arm.
3
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Open the Project page. From the Units menu verify: •
Project units are set to “Metric (kg, mm, s, C, mA, mV).
•
“Display Values in Project Units” is checked (on).
4
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
… Project Schematic 1.
From the Toolbox double click “Static Structural” to create a new system.
1.
2.
RMB the geometry cell and “Import Geometry” and browse to “Mesh_Arm_2.stp”.
3.
Double click the “Model” cell to open the Mechanical application.
5
© 2012 ANSYS, Inc.
December 19, 2012
2.
3.
Release 14.5
Preprocessing 4. Set the working unit system: –
“Units > Metric (mm, kg, N, s, mV, mA)”. 7.
5. Apply the tensile force on the a rm (hi ghlight the stat ic structural branch):
a. Highlight the smaller interior cylindrical face. b. RMB > Insert > Force c. In the detail window choose the component method and c.
enter 5000N in the Y direction. b.
a.
6
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 6.
Apply the bending force to the arm:
a. Highlight the circular face at the base of the smaller end of the arm.
a.
b. “RMB > Insert > Force”. c. In the detail window choose the component method and enter 1000N in the -Z direction.
b.
c.
7
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Preprocessing 7.
Apply the fixed support on the arm:
a. Select the larger diameter interior cylindrical face. b. RMB > Insert > Fixed Support.
b.
a.
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© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Meshing 8.
Mesh the arm using all default settings:
a. Highlight the mesh branch. b. “RMB > Generate Mesh”. a.
b.
Inspection of the completed mesh shows a very coarse result. In real applications we would likely refine the mesh before solving.
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© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Meshing 9. Check the element quality:
a. Highlight the Mesh branch. b. In the Statistics details set “Mesh Metric” to “Element Quality”.
a.
b.
The element quality plot shows that some elements are of a relatively low quality. However, to illustrate some of the practices and tools we’ll solve the model as it is.
10
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December 19, 2012
Release 14.5
Solution 10. Request Results:
a. Highlight the “Solution” branch (A6). b. RMB > Insert > Stress > Equivalent Von Mises Stress. c. RMB > Insert > Stress > Error. b. a.
c.
11. Solve the mo del:
a. Click Solve. a.
11
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Result Interpretation 12. View Initial Results: The stress result shows one of the web sections may be an area of concern. In reviewing the error plot however we confirm there is a rapid transition from high to low energy in adjacent elements. This is an indication that mesh refinement is recommended.
Structural Error 12
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Re-Meshing At this point there are numerous mesh controls w e could employ to improve the mesh. We’ll focus on the potential problem area indicated in the results using several meshing controls. 13. Change the globa l mesh setti ngs:
a. Highlight the mesh branch. b. In the details change the “Relevance Center” to “Medium”.
b.
a.
13
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Re-Meshing 14. Add a me sh size control:
a. Highlight the 2 faces at the bottom of the cavity (shown at right). b. Choose “Extend to Limits”. c. RMB > Insert > Sizing. d. In the details set the element size to 3mm.
a.
c.
b.
d.
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Note: extend to limits should result in 72 faces being selected.
Release 14.5
. . . Re-Meshing 15. Remesh the model:
a. Highlight the “Mesh” branch. b. RMB > Generate Mesh.
a.
b. The new mesh shows we’ve accomplished refinement around the region of interest.
15
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December 19, 2012
Release 14.5
. . . Re-Meshing 16. Again reviewing the element quality metric from the mesh statistics detail an improvement can be seen.
Original Mesh
16
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December 19, 2012
Refined Mesh
Release 14.5
. . . Results – Solve the model and review results as before. – A comparison of stresses from our srcinal mesh shows the maximum value has gone from approximately 62 to 60.6 MPa
Original Mesh
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December 19, 2012
Refined Mesh
Release 14.5
. . . Results Compare error plots for the region of interest.
Original Mesh •
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Refined Mesh
It’s clear the refinement has reduced the rapid transition in energy values when compared to the srcinal mesh.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Conclusion Notice that there are still areas of high energy transition in the model. Our mesh refinement has addressed our stated goal but not the entire model. Each simulation is unique and will require different approaches to insure high quality results.
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Release 14.5
Workshop 12.1 Parameter Management 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals •
•
Use the Workbench Parameter Workspace to setup multiple scenarios to explore structural responses in the bracket shown. Material thickness will be varied in the gusset with the bracket thickness held constant then the process will be reversed.
Bracket Gusset
2
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Project Schematic Open the Project page. From the Units menu verify: •
Project units are set to “Metric (kg, mm, s, C, mA, mV).
•
“Display Values in Project Units” is checked.
3
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December 19, 2012
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. . . Project Schematic 1. From the Toolbox double click “Static Structural” to create a new system.
1.
2. RMB the geometry cell and “Import Geometry” and browse to “Bracket.stp”.
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2.
Release 14.5
Preprocessing 3. Double click the “Model” cell to open the Mechanical application.
3.
4. Set/verify the working unit system: – “Units > Metric (mm, kg, N, s, mV, mA)”.
5
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December 19, 2012
4.
Release 14.5
. . . Preprocessing 5. Highlight the part “Bracket” and enter a thickness = 2mm in the details. 6. Highlight the part “Gusset” and enter a thickness = 1mm in the details. 7. Make both thicknesses parametric by toggling the check box.
5. 7. 6. 8. Highlight the Geometry branch and, in the Property details, toggle the Mass parameter on.
8. 6
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December 19, 2012
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. . . Preprocessing 9.
Highlight the Connections branch, RMB > In sert > Connections Group.
9.
10. In the details for the connections group change the Auto Detections for Face/Edge to “Yes”.
10.
11. Highlight the connections group “RMB > Create Automatic Connections”. 7
© 2012 ANSYS, Inc.
December 19, 2012
11. Release 14.5
Environment 12. Apply constraints to the model (highlight “Static Structural” branch (A5):
a.
a. Select the edge of one hole. b. RMB > Insert > Fixed Support. c. Highlight the face surrounding the fixed hole. d. RMB > Insert > Frictionless Support.
b.
d.
c.
8
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December 19, 2012
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. . . Environment 13. Apply Loads to the model:
a. b. c. d.
Select the of the hole shown below.
RMB > Insert > Force.
c.
In the Details switch to the component method. Enter a magnitude of -20 N in th e X direction.
d. a. b.
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Solution Setup 14. Insert Results (highlight Solution branch (A6):
a.
a. RMB > Insert > Stress > Equivalent (von Mises).
15. In the resul t detail, toggle the “Maximum” result as a parameter.
15.
10
© 2012 ANSYS, Inc.
December 19, 2012
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Parameter Management 16. Access the Parameter Set:
a. From the schematic double click “Parameter Set”. When the parameter workspace opens make sure the 2 thicknesses, the mass and the stress are all shown in the parameter list.
a.
11
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December 19, 2012
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. . . Parameter Management 17. Enter thickness values as shown below. For the first 3 DPs the bracket will be held constant while the gusset thickness varies. For the last 3 the reverse will be solved.
17.
18. “Update All Design Points” will instruct Mechanical to execute a solve for each scenario in the Design Point table.
18. 12
© 2012 ANSYS, Inc.
December 19, 2012
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. . . Para meter Management Once the update process begins a message will appear as shown here. In fact the Mechanical application window will close during the update process. This is normal.
When the updates are complete the table will show calculated values for both output parameters.
13
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December 19, 2012
Release 14.5
. . . Parameter Management 19. There are several wa ys we can pre sent the design point information. In this case we’ll see how output quantities vary with each design point:
a. Highlight the output parameter “Equivalent Stress Maximum” (P5 here). b. Double click the “Design Points Vs P5” choice in the Toolbox (again, parameter numbers will vary depending on the order of their definition).
b. a.
•
14
Repeat the above steps with the “Geometry Mass” parameter (P3 in this case).
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Parameter Management 20. Highlight the stress per design point chart to display (here the charts have been renamed according to their content):
20.
Stress per Design Point
15
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December 19, 2012
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. . . Para meter Management 21. Highlight the mass plot to display.
21.
Mass per Design Point
16
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December 19, 2012
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. . . Para meter Management Repeat step 19 and create a stress vs DP plot. In the properties window choose to display “Geometry Mass” on the right side Y axis as shown below.
Plots like this one allow us to visualize the trade off that often accompanies these kinds of choices. 17
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December 19, 2012
Release 14.5
Appendix A Linear Buckling Analysis 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Chapter Overview In this chapter, performing linear buckling analyses in Mechanical will be covered.
Contents:
A. Background On Buckling B. Buckling Analysis Procedure C. Workshop 7-1
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A. Background on Buckling Many structures require an evaluation of their structural stability. Thin columns, compression members, and vacuum tanks are all examples of structures where stability considerations are important. At the onset of instability (buckling) a structure will have a very large change in displacement { x} under essentially no change in the load (beyond a small load perturbation).
F
F Stable
3
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Unstable
Release 14.5
… Background on Buckling Eigenvalue or linear buckling analysis predicts the theoretical buckling strength of
an ideal linear elastic structure. This method corresponds to the textbook approach of linear elastic buckling analysis. •
The eigenvalue buckling solution of a Euler column will match the classical Euler solution.
Imperfections and nonlinear behaviors prevent most real world structures from achieving their theoretical elastic buckling strength. Linear buckling generally yields unconservative results by not accounting for these effects. Although unconservative, linear buckling has the advantage of being computationally cheap compared to nonlinear buckling solutions.
4
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… Basics of Linear Buckling For a linear buckling analysis, the eigenvalue problem below is solved to get the buckling load multiplier i and buckling modes i:
K l S y i
i
0
Assumptions: •
[K] and [S] are constant:
– Linear elastic material behavior is assumed – Small deflection theory is used, and no nonlinearities included
It is important to remember these assumptions related to performing linear buckling analyses in Mechanical.
5
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B. Buckling Analysis Procedure A Static Structural analysis will need to be performed prior to (or in conjunction with) a buckling analysis.
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… Geometry and Material Properties Any type of geometry supported by Mechanical may be used in buckling analyses: •
Solid bodies
•
Surface bodies (with appropriate thickness defined)
•
Line bodies (with appropriate cross-sections defined)
– Only buckling modes and d isplacement results are available for line bodies. •
Although Point Masses may be inclu ded in the model, only inertial loads affect point masses, so the applicability of this feature may be limited in buckling analyses
For material properties, Young’s Modulus and Poisson’s Ratio are required as a minimum
7
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… Contact Regions Contact regions are available in free vibration analyses, however, contact behavior will differ for the nonlinear contact types exactly as with modal analyses. Discussed earlier (see chapter 5).
Contact Type Bonded NoSeparation Rough Frictionless
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Initially Touching Bonded NoSeparation Bonded NoSeparation
Linear Buckling Analysis Inside Pinball Region Outside Pinball Region Bonded Free NoSeparation Free Free Free Free Free
Release 14.5
… Loads and Supports At least one structural load, which causes buckling, should be applied to the model: •
All structural loads will be multiplied by the load multiplier (l) to determine the buckling
load (see below). •
Compression-only supports are not recommended.
•
The structure should be fully constrained to prevent rigid-body motion.
Fx
= Buckling Load
In a buckling analysis all applied loads (F) are scaled by a multiplication factor ( ) until the critical (buckling) load is reached 9
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
… Loads and Supports Special considerations must be given if constant and proportional loads are present. •
• •
10
The user may iterate on the buckling solution, adjusting the variable loads until the load multiplier becomes 1.0 or nearly 1.0. Consider the example of a column with self weigh t WO and an externally applied force A. A solution can b e reached by iterating while adjusting th e value of A until insures the self weight = actu al weight or WO * WO .
© 2012 ANSYS, Inc.
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= 1.0. This
Release 14.5
… Buckling Setup Buckling analyses are always coupled to a structural analysis within the project schematic. • •
11
The “Pre-Stress” object in the tree contains the results from a structural analysis.
The Details view of the “Analysis Settings” under the Linear Buckling branch allows the user to specify the number of buckling modes to find.
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
… Solving the Model After setting up the model the buckling analysis can be solved along with the static structural analysis. •
•
12
A linear buckling analysis is more computationally expensive than a static analysis on the same model. The “Solution Information” branch provides detailed solution output.
© 2012 ANSYS, Inc.
December 19, 2012
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… Reviewing Results After the solution is complete, the buckling modes can be reviewed: •
The Load Multiplier for each buckling mode is shown in the Details view as well as th e graph and chart areas. The load multiplier times the applied loads represent the predicted buckling load.
Fbuckle = (Fapplied x
13
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)
Release 14.5
… Reviewing Results Interpreting the Load Multiplier ( ): •
14
The tower model below has been solved twice. In the first case a unit load is applied. In the second an expected load applied (see next page)
© 2012 ANSYS, Inc.
December 19, 2012
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… Reviewing Results Interpreting the Load Multiplier ( ):
BucklingLoad
15
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l *Unit
BucklingLoad
BucklingLoad
BucklingLoad Actual _ Load
_ Load
l
l * Actual _
l
Load
Safety _ Factor
Release 14.5
… Reviewing Results The buckling load multipliers can be reviewed in the “Timeline” section of the results under the “Linear Buckling” analysis branch •
16
It is good practice to request more than one buckling mode to see if the structure may be able to buckle in more than one way under a given applied load.
© 2012 ANSYS, Inc.
December 19, 2012
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C. Workshop AA.1 – Linear Buckling •
•
Workshop WSAA.1 – Linear Buckling Goal: – Verify linear buckling results i n Mechanical for the pipe model shown below. Results will be compared to closed form calculations from a handbook.
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© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Goals The goal in this workshop is to verify linear buckling results in ANSYS Mechanical. Results will be compared to closed form calculations from a handbook. Next we will apply an expected load of 10,000 lbf to the model and determine its factor of safety. Finally we will verify that the structure’s material will not fail before buckling occurs.
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Assumptions The model is a steel pipe that is assumed to be fixed at one end and free at the other with a purely compressive load applied to the free end. Dimensions and properties of the pipe are: OD = 4.5 in ID = 3.5 in. E = 30e6 psi, I = 12.7 in^4, L = 120 in. In this case we ass ume the pipe conforms to the following handbook formula where P’ is the critical load:
E I P' K L 2
2
For the case of a fixed / free beam the parameter K = 0.25.
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Assumptions •
Using the formula and data from the previous page w e can predict the buckling load will be:
2 P ' 0.25 30e6 12 2 .771 65648.3lbf ( 120 )
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Project Schematic 1. Double click Static Structural in the Toolbox to create a new system.
1. 2. Drag/drop a “Linear Buckling” system onto the “Solution” cell of the static structural system.
2.
21
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Project Schematic •
When the schematic is correctly set up it should appear as shown here.
“Drop Target”
•
22
The “drop target” from the previous page indicates the outcome of the drag and drop operation. Cells A2 thru A4 from system (A) are shared by system (B). Similarly the solution cell A6 is transferred to the system B setup. In fact, the structural solution drives the buckling analysis. © 2012 ANSYS, Inc.
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Release 14.5
Project Schematic Verify that the Project units are set to “US Customary (lbm, in, s, F, A, lbf, V). Verify units are set to “Display Values in Project Units”.
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. . . Project Schematic 3. From the static structural system (A), double click the Engineering Data cell.
3.
4. To match the hand calculations referenced earlier, change the Young’s modulus of the structural steel. Highlight Structural Steel. a. b. Expand “Isotropic Elasticity” and modify
c.
Young’s Modulus to 3.0E7 psi. “Return to Project”.
a.
c. Note : changing this property here does not affect the stored value for Structural Steel in the General Material library. To save a material for future use we would “Export” the properties as a new material to the material library. 24
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b. Release 14.5
. . . Project Schematic 5. From the static structural system (A), RMB the Geometry cell and “Import Geometry”. Browse to the file “Pipe.stp”.
5.
6. Double click the M odel cell to s tart Mechanical. 6.
•
25
When the Mechanical application opens the tree will reflect the setup from the project schematic. © 2012 ANSYS, Inc.
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Release 14.5
Preprocessing 7. Set the working unit system to the U.S. customary system: a. U.S. Customary (in, lbm, psi, °F, s, V, A).
8. Apply constraints to the pipe:
a.
a. Highlight the Static Structural branch (A5). b. Select the surface on one end of the pipe. c. “RMB > Insert > Fixed Support”.
b. c.
a.
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Environment 9. Add bu ckling l oads:
a. Select the surface on the opposite end of the pipe from the
a.
fixed support.
b. “RMB > Insert > Force”. c. In the force detail change the “Define by” field to “Components”.
d. In the force detail enter “1” in the “Magnitude” field for the “Z Component” (or use -1 depending on which ends of the pipe are selected).
b.
c. d.
27
© 2012 ANSYS, Inc.
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. . . Environment 10. Solve the model:
a. Highlight the Solution branch for the Linear Buckling analysis (B6) and Solve.
– Note, this will automatically trigger a solve for the static structural analysis above it.
11. When the solu tion completes:
a. Highlight the buckling “Solution” branch (B6). graph and the Tabular Data will display – The Timeline st
the 1 buckling mode (more modes can be requested).
a.
b. RMB in the Timeline and ch oose “Select All”. c. RMB > “Create Mode Shape Results” (this will add a “Total Deformation” branch to the tree).
c. a. b. 28
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Results – Click “Solve” to view the first mode
29
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. . . Results 12. Change the force value to the expected load (10000 lbf):
a. Highlight the “Force” under the “Static Structural (A5)” branch
b. In the details, change the “Z Component” of the force to 10000 (or use -10000 depending on your selections).
11a.
13. Solve:
a. Highlight the Linear Buckling Solution branch (B6), RMB and “Solve”.
12a.
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11b. Release 14.5
. . . Results When the solution completes note the “L oad Multiplier” field now shows a value of 6.56. Since we now have a “real world” load applied, the load multiplier is interpreted as the buckling factor of safety for the applied load.
Given that we have already calculated a buckling load of 65600 lbf, the result is obviously trivial (65600 / 10000). It is shown here only for completeness.
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Verification A final step in the buckling analysis is added here as a “best practices” exercise.
We have already predicted the expected buckling load and calculated the factor of safety for our expected load. The results so far ONLY indicate results as they relate to buckling failure. To this point we can say nothing about how our expected load will affect the stresses and deflections in the s tructure.
As a final check we will verify that the expected load (10000 lbf) will not cause excessive stresses or deflections before it is reached.
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. . . Verification 14. Review Stresses for 10,00 0lbf load:
a. Highlight the “Solution” branch under the “Static Structural” environment (A6).
b. RMB > Insert > Stress > Equivalent Von Mises Stress. c. RMB > Insert > Deformation > Total. d. Solve. a.
b.
c.
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. . . Verification A quick check of the stress results shows the model as loaded is well within the mechanical limits of the material being used (Engineering Data shows compressive yield = 36,259 psi). As stated, this is not a required step in a buckling analysis but should be regarded as good engineering practice.
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Appendix B Submodeling 14.5 Release
Introduction to ANSYS Mechanical 1
© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
C. Workshop BB.1 – Submodeling •
•
Workshop WSBB.1 – Submodeling Goal: – Solve a full model (coarse mesh) and then setup and solve a submodel representing a portion of the full model (fine mesh).
Full Model 2
© 2012 ANSYS, Inc.
December 19, 2012
Submodel Release 14.5
Approach Submodeling requires the use of 2 geometry models. One model to represent the full geometry and another representing a portion of the full model. For this exercise we used the ANSYS DesignModeler application to slice a piece from the full model.
Full Model 3
© 2012 ANSYS, Inc.
December 19, 2012
Submodel Release 14.5
Project Schematic Begin a new Workbench session and, from the Project page, choose “Restore Archive . . . “ and browse to the file “Submodeling_WS_APPXB.wbpz” and Open (location provided by instructor). When prompted, “Save” using the default name and the same location.
From the “Units” menu verify: •
Project units are set to “Metric (kg, mm, s, ºC, mA, N, mV).
•
“Display Values in Project Units” is checked (on).
4
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. . . Project Schematic When the archive is opened note the existing static structural system has been renamed “Full Model”. 1.
From the Static Structural system double click (or RMB > Edit) the “Model” cell.
2.
When Mechanical opens, verify the units are set to “Metric (mm, kg, s, mV, mA)”.
5
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1.
2.
Release 14.5
Preprocessing 3.
Highlight the mesh branch, RMB > G enerate Mesh.
3. 4. Apply a pressure load:
a. With the static structural branch highlighted, select one of the interior surfaces of the housing and choose “Extend to Limits” (should result in 13 faces).
b. “RMB > Insert > Pressure”. c. Enter Magnitude “1000” Mpa in the details.
4b. 4c.
4a. 6
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. . . Preprocessing 5.
Add a force to the housing: a. Select the cylindrical face of the center hole in the housing.
5a.
b. “RMB > Insert > Force”. c. Define by components and enter 200 N X componen t.
6.
Add a compression only support: a. Select the planar surface on the back of the housing. b. “RMB > Insert > Compression Only Support”.
5b.
6a.
5c.
6b. 7
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December 19, 2012
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. . . Preprocessing 7.
Create a named selection containing the countersink faces:
a. Highlight one countersink face, RMB > Create Named Selection.
b. In the dialog box enter “Countersinks” and “Apply geometry
7a.
items of same: size” and OK.
– The resulting NS should contain 8 faces as shown.
7b.
8
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. . . Preprocessing 8.
Add frictionless supports to countersink faces: a.
Highlight the Static Structural branch.
b.
RMB > Insert > Frictionless Support.
c.
In the details change scoping method to “Named Selections”.
d.
Select the “Countersinks” named selection.
8a.
8c. 8d.
8b. 9. 9
Solve © 2012 ANSYS, Inc.
9. December 19, 2012
Release 14.5
Full Model Solution 10. When the solution completes highlight the Solution branch:
a. Insert an Equivalent Stress object, RMB > Evaluate All Results.
10a.
As the plot shows the potential problem areasare around the countersink holes in the housing. An efficient approach to investigatethese areas in more detail is to create a submodel of this part of the geometry. In this example we have used ANSYS DesignModeler geometry application to slice out a portion of the model which we will use next.
10
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Submodeling Schematic 11. Set up the Submodel in the project: a. Drag & Drop a new standalone Static Structural system into the project and rename “Submodel”. b. From the geometry cell in the new system RMB > Import Geometry > browse to the file “Submodel3.stp”. c. Drag & D rop the Solution cell from th e full model onto the Setup cell in the submodel.
11a.
d. Double click the Model cell to start Mechanical.
11b .
11d. 11c 11
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Release 14.5
. . . Preprocessing 12. When Mechanical opens, mesh the submodel: a. Highlight the Mesh branch and, in the Sizing section of the details enter Element Size = 2 mm. b. From the Mesh branch RMB > Insert > Method and scope it to the body of the geometry.
12a.
c. Change the method to “Hex Dominant”. d. From the mesh branch RMB > Generate Mesh.
12b.
Note that in the interest of time we have not refined the mesh as much as one might in actual practice.
12c.
12d. 12
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Importing Displacements In the new Mechanical session you will see a “Submodeling” branch. 13. Import displacements from the full model: a. Highlight “Submodeling” RMB > Insert > Displacement.
13d.
13
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December 19, 2012
Release 14.5
. . . Importing Displacements 14. Map displacements from the full model onto the submodel:
14a.
a. Select the 3 faces on the model representing the cut boundaries.
b. In the details of the imported displacement “Apply” the selected geometry.
c. Highlight “Imported Displacement” RMB > Import Load.
14b.
Since the solution of the full model was static, the default import is from the “End Time”. If the full model had been a multi-step or transient analysis we could have chosen any solution points to map from. 14
© 2012 ANSYS, Inc.
December 19, 2012
14c. Release 14.5
Adding Boundary Conditions Add boundary conditions to match the full model. 15. Highlight the static structural branch and add a frictionless support: a. Select the countersink face, RMB > Insert > Frictionless Support.
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16. Highlight the static structural branch and add a compression only support: a. Select the bottom fac e of the submodel , RMB > Insert > Compression Only Support.
Recall that the full model contained both a pressure load and a force. Since no part of the submodel contains regions where these loads were applied we do not add them. Their effect is seen in the displacements mapped to the cut boundaries.
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© 2012 ANSYS, Inc.
December 19, 2012
16a.
Release 14.5
Solving the Submodel 17. Solve.
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If we add equivalent stress to the submodel and compare it to the full model, a significant change can be seen (> 20%). A part of any submodeling solution should include some form of verification regarding the location of the cut boundaries. The goal is to evaluate the results of both models on or near the cut boundary to make sure they are in reasonable agreement. If they do not agree it indicates the cut boundaries are too close to the stress concentration.
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© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
Cut Boundary Verification One technique might be to simply query the model using probes to get a feel for how well the 2 results agree. While this is quick and easy, a drawback is it relies on an “eyeball” location for the probes. Another technique is to compare path plots (see next page).
Although not part of the workshop, if time permits, you may complete the verification techniques shown on the remainder of the pages.
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© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Cut Boundary Verification In the submodel we choose the corner points and connect them with a path. From the selection information we can determine where these end points need to be in the full model in order to duplicate the path. Here we have located 2 coordinate systems in the full model using the selection information from the submodel.
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© 2012 ANSYS, Inc.
December 19, 2012
Release 14.5
. . . Cut Boundary Verification Comparing the 2 path plots indicates we have reasonably good agreement between the models near the cut boundaries.
Submodel 19
© 2012 ANSYS, Inc.
December 19, 2012
Full Model Release 14.5
