Getting Started Using Adams/Chassis - MD Adams 2010

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Getting Started Using Adams/Chassis • Introducing Adams/Chassis • Working with Half-Suspension Models • Analyzing the Effect of Design Changes • Working with Full-Vehicle Models • Working with Leaf Springs • Integrating Control Systems in Your Model

2 Getting Started Using Adams/Chassis

Introducing Adams/Chassis

Introducing Adams/Chassis 3 Overview

Overview This chapter contains the basics of the Adams/Chassis analysis environment and introduces the tutorials found in later chapters: • About Adams/Chassis ... • What You Will Learn • Starting Adams/Chassis • Familiarizing Yourself with Adams/Chassis

4 Getting Started Using Adams/Chassis About Adams/Chassis

About Adams/Chassis Adams/Chassis provides a complete analysis environment for automotive Adams analysis. It does this by providing standard model types, two analysis types, and post-processing. You You run Adams/Chassis in conjunction with Adams/Solver and Adams/PostProcessor. Adams/Chassis comes with many standard suspensions such as: • Short-long arm • MacPherson • Hotchkiss • 4 Link • Quadralink

Using Adams/Chassis, you can perform the following types of analyses, also referred to as events: • Half-vehicle analyses - During half-vehicle analyses you examine the behavior of suspensions.

Half-vehicle analyses include: • Ride motion • Roll motion • Steering • Compliance • Full-vehicle analyses - During full-vehicle analyses you examine the behavior of complete

vehicles. Full-vehicle analyses include: • Step steer • Frequency response • Oncenter handling • Constant radius

The majority of these standard events come wi th standard postprocessing; that is, plots or reports or both. Adams/Chassis also helps you with the virtual prototyping process by: • Substituting rigid bodies with flexible bodies through Adams/Chassis Makeflex and

Adams/Flex. • Modeling complex leaf spring interactions with Adams/Chassis Makeleaf. • Using Adams/SmartDriver to learn how to best drive a course.

Introducing Adams/Chassis 5 What You Will Learn

What You Will Learn This guide contains five tutorials that step you through the traditional iterative analysis process, which is one of the many ways you can solve complex system problems using Adams/Chassis. The first three tutorials build on each other and assume that you work through them in sequence. The last tw o tutorials in the final chapter are independent of the other tutorials. How ever, they still assume that you have learned the Adams/Chassis interface by running through the other tutorials. In the tutorials, you will perform the following tasks: • Build half-suspension, full-vehicle models, and leaf-spring models. • Analyze models in different virtual tests. • Review analyses using animation, plotting, and reports. • Modify models and review the effects of your design changes. • Iterate your design to achieve performance targets for your model.

6 Getting Started Using Adams/Chassis Starting Adams/Chassis

Starting Adams/Chass Adams/Chassis is In this section you learn how to start Adams/Chassis in the UNIX and the Windows environment. You You must run Adams/Chassis in a directory to which you have write permissions. The example models in the installation are always write protected. You must use Database Utilities to copy the example model from the installation directory to your working directory. Database utilities automatically changes the permission for you so that the files can be overwritten.

To start Adams/Chassis in the UNIX environment: 1. At the command prompt, prompt, enter enter the command to start start the Adams Toolbar, Toolbar, and then then select Enter. mdadamsx, where x is the version The standard command that MSC.Software provides is mdadamsx, mdadams2010. number, for example mdadams2010. The Adams Toolbar appears. 2. Sele Select ct the the Adams/Chassis tool

.

3. Sel Select OK . The Adams/Chassis main window appears as shown in the figure below.

To start Adams/Chassis in the Windows environment: 1. From From the the Start menu, point to Programs, point to MSC.Software, point to MD Adams 2010 , point to AChassis , and then select Adams - Chassis . 2. Sel Select OK . The Adams/Chassis window appears as shown below. below.

Introducing Adams/Chassis 7 Starting Adams/Chassis

Treeview

Property Editor

Figure 1

Adams/Chassis Build Mode

8 Getting Started Using Adams/Chassis Familiarizing Yourself with Adams/Chassis

Familiarizing Yourself with Adams/Chass Adams/Chassis is Here you will learn about the Adams/Chassis work modes and toolbars.

Adams/Chassis Work Modes Adams/Chassis is divided into four work modes: • Build • Test • Review • Improve

Build The Build mode allows you to edit model data and change system configuration. You can also work on multiple models at once. The Build mode is the default for starting Adams/Chassis.

Test The Test mode allows you to build and run your model.

Review The Review mode allows you to visualize analysis results using Adams/PostProcessor. Adams/PostProcessor. You You can postprocess the output of standard Adams/Chassis events. Postprocessing has two formats: reports and plots. A majory of standard Adams/Chassis events have either a report, a plot, or both. You You can also create an animation of your event.

Improve The Improve mode allows you to refine models with Adams/Insight. Here you can use the features from Adams/Insight to create sophisticated experiments for measuring the performance of your model. It also provides a collection of statistical tools for analyzing the results of your experiments so that you can better understand how to refine and improve your model.

Learning About the Toolbars The toolbars in Adams/Chassis change according to the work mode. Below is the basic toolbar that is available in all work modes.

Introducing Adams/Chassis 9 Familiarizing Yourself with Adams/Chassis

Figure 2

Adams/Chassis Basic Toolbar

The following figures show the toolbars that are available in each work mode:

Figure 3

Adams/Chassis Build Mode Toolbar

Figure 4

Adams/Chassis Test Mode Toolbar

10 Getting Started Using Adams/Chassis Familiarizing Yourself with Adams/Chassis

Figure 5

Adams/Chassis Review Mode Toolbar

Figure 6

Adams/Chassis Improve Mode Toolbar

Introducing Adams/Chassis 11 Familiarizing Yourself with Adams/Chassis

Learning about the Treeview The Adams/Chassis treeview changes according to the work mode. The treeview has different features in each work mode. Below are the two basic secti ons of the treeview:

Bookshelf

Treeview

12 Getting Started Using Adams/Chassis Learning About Preferences

Learning About Preferences You set preferences to define the work environment specific to the machine you are using. Before running Adams/Chassis, you must either set up the preferences or load an existing preferences file. Incorrect preference settings can prevent Adams/Chassis from performing even the most basic functions. You must have the following preferences set for Adams/Chassis to work properly: • Working directory - specifies the directory for all output files • Temporary file directory - must be a valid directory

To set preferences: 1. From From the the Edit menu, select Preferences. The Preferences window appears. 2. In the Prefere Preferences nces window, window, select select the Find tool

next to Current Working Directory.

The Browse for Folder window appears. 3. Select a current current working directory directory from from the list, and then select select OK . 4. In the Preferences window, make sure sure that a text editor is present for Text Editor Command. 5. Optionally, enter a Graphical Difference Command to launch a graphical differencing differencing tool such as SGI/usr/sbin/gdiff or freeware tool, ExamDiff for Windows. 6. In the Prefere Preferences nces window, window, select select the Find tool

next to Temporary Files Directory.

7. Select Select a direct directory ory from from the the Browse for Folder window, and then select OK .

Note:

This directory must already exist and the directory path must not contain spaces.

8. The remaining remaining options options in the Preferences Preferences window window are optional. optional.

Working with Half-Suspension Models 1

Working with Half-Suspension Models

2 Getting Started Using Adams/Chassis Overview

Overview In this chapter you complete a build-run-modify-compare analysis cycle. Adams/Chassis has been developed to make this process as quick and easy as possible. This chapter contains the following sections: • Copying Example Vehicle Database • Registering a Database • Selecting a Vehicle System File • Running an Analysis • Animating a Model • Plotting Analysis Results • Running an Analysis with Alignment • Comparing Results

The tutorial takes about 45 minutes to complete.

Working with Half-Suspension Models 3 Copying Example Vehicle Database

Copying Example Vehicle Database In this section, you load example data files for your Adams/Chassis session. Data files are the inputs to Adams/Chassis. They contain the full set of parameters for vehicle models.

To copy a database: 1. In the the Build Build mode, mode, from from the the Utilities menu, select Database Utilities. The Database Utilities window appears. 2. In the Copy Database Database tab, tab, select select the the Find tool

.

The Select .vdb Directory to Copy window appears. 3. In the Select Select .vdb .vdb Directory Directory to Copy Copy window, window, select select achassis_gs.vdb, and then select OK. 4. In the Database Database Utilities Utilities window, window, select select Copy Database to Working Directory. Adams/Chassis copies the achassis_gs example database to your working directory. 5. At the the promp prompt, t, selec selectt OK. 6. Close the Database Database Utilities Utilities window. window.

4 Getting Started Using Adams/Chassis Registering a Database

Registering a Database You can reference multiple registered databases for access. Databases are registered in the Preferences window. Here you register achassis_gs.vdb. To register a database: 1. From From the the Edit menu, select Preferences. 2. In the Database Database Registr Registration ation section section,, select select Add New. 3. Sel Select achassis_gs.vdb from your working directory, and then select Ok . 4. Sel Select Save to save these settings.

Working with Half-Suspension Models 5 Selecting a Vehicle System File

Selecting a Vehicle System File Here you will select your vehicle system file.

To select a vehicle system file: 1. From From the toolb toolbar, ar, selec selectt the Load Model

button.

2. In the the Select Select File File window, window, select achassis_gs from the Registered Databases section.

3. Select lect achassis_gs_front_sys.xml, and then select Open. Adams/Chassis loads the model into the treeview.

6 Getting Started Using Adams/Chassis Running an Analysis

Running an Analysis You now run an analysis on the front suspension to exercise the left and right wheel centers 20 mm into jounce, then 20 mm into rebound.

To run an analysis: 1. From the the main toolbar, toolbar, select select the the Test mode

.

2. In the book bookshe shelf, lf, expa expand nd Suspension. 3. Doub Double le-c -cli lick ck Front Ride Motion. You will see that the event, achassis_gs_front_sys_fride has been added to the fingerprint tree and displayed in the property editor.

4. Do one one of the the follow following ing:: • Right-click achassis_gs_front_sys_fride and then select Build and Run Selected Events . • Select the Build and Run Selected Events tool

.

5. When the event event is complete, complete, close close the command command window. window.

Working with Half-Suspension Models 7 Animating a Model

Animating a Model You animate the model to t o see the effects of the analysis, to check that your model is being assembled as you like, and to check model geometry.

To animate your model: 1. From From the toolb toolbar, ar, selec selectt the Review mode

.

2. In the the treev treeview, iew, select select achassis_gs_front_sys_fride. 3. From From the toolb toolbar, ar, selec selectt the Execute Selected Animations tool

.

Adams/Chassis launches Adams/PostProcessor, a post-processing tool that lets you view the results of simulations you performed. See the online help for Adams/PostProcessor for more information. 4. On the the menu menu toolbar, toolbar, select the Play tool

.

This animates the ride motion simulation. 5. After the suspensi suspension on goes through through a complete complete animation, animation, select the Pause tool

.

6. To exit Adams/PostPr Adams/PostProcess ocessor, or, from from the File menu, select Exit, and then select Exit, Don’t Save .

8 Getting Started Using Adams/Chassis Plotting Analysis Results

Plotting Analysis Results Most Adams/Chassis standard analyses have plots or reports, or both, associated with them. For the halfsuspension ride motion analysis, there are plots and reports. To check if there are plots or reports associated with t he analysis you just ran, look for checkboxes in the property editor, next to analysis name, under Plots and Reports. Notice that there are plots and reports associated with the achassis_gs_front_sys_fride analysis.

To plot analysis results: 1. In the the Adams/Ch Adams/Chassis assis window, window, make sure that achassis_gs_front_sys_fride is selected in the treeview. 2. From From the toolb toolbar, ar, sele select ct the Execute Selected Plots tool

.

To display the plots, Adams/Chassis launches Adams/PostProcessor. The standard plots for ride motion include: Toe, caster, and camber versus wheel travel Wheel rate versus wheel travel Vertical force versus wheel travel The figure below shows some of the standard plots.

Working with Half-Suspension Models 9 Plotting Analysis Results

Figure 7

Standard Plots for Ride Motion

3. To review the differen differentt plot pages, in the treeview treeview on the left, click click each page. 4. From From the the File menu, select Exit. Adams/PostProcessor asks you if you want to save the plots. 5. Select lect Exit, don’t save.

10 Getting Started Using Adams/Chassis Running an Analysis with Alignment

Running an Analysis with Alignment In this section, you run an analysis with the same model data, but with wit h toe, caster, and camber alignment. Before you run the analysis, you add an event to your session. We call this a fingerprint session. You You can save and load fingerprints. In Adams/Chassis you can create an unlimited number of events in a single session. When using a fingerprint, you can refer to the same vehicle configuration files for all t he analyses, or use different vehicle configuration files.

To add an event tab to the current fingerprint: 1. From From the toolb toolbar, ar, sele select ct the Test mode tool . 2. From the booksh bookshelf, elf, double-clic double-click k Front Ride Motion. Adams/Chassis adds another analysis to your fingerprint tree. The second analysis refers to the same vehicle configuration files as the first analysis. If you modify one of the vehicle configuration files, the modification will affect future builds for both events. Adding an event did database, that is, the not create copies of the of the vehicle configuration file or database, second analysis will use the same files.

To run an analysis with alignment: 1. In the the propert property y editor, editor, select select Front Auto-Alignment. 2. Set Total Toe to 0.1. 3. Set Avg. Caster to 4.0. 4. Set Avg. Camber to -0.5. 5. Sele Select ct the the Build and Run Selected Events tool

.

Adams/Chassis analyzes your model. At the beginning of the analysis, Adams/Chassis invokes the auto-aligner. The auto-aligner adjusts various parts of the front suspension to iteratively achieve the desired values for toe, caster, and camber. 6. When the analysi analysiss is complete, complete, close close the the window. window.

Working with Half-Suspension Models 11 Comparing Results

Comparing Results In this section, you compare the results of the two analyses you ran.

To compare results: 1. From From the toolb toolbar, ar, selec selectt the Review mode

.

Note that both analyses appear in the fingerprint tree. 2. Shift-click Shift-click to select select both analyses analyses in the fingerprint fingerprint tree. tree. 3. Veri Verify fy tha thatt Overlay Plots/Reports of Same Events is checked. This option overlays the plot data for the two analyses so you can easily compare results. 4. Select lect Execute Selected Plots

.

Adams/PostProcessor displays two curves in every plot, similar to the figure below.

Figure Figure 8

Compariso Comparison n Plots

12 Getting Started Using Adams/Chassis Comparing Results

Notice that for achassis_gs_front_sys_fride_2 for achassis_gs_front_sys_fride_2:: achassis_gs_front_sys_fride_2 is aligned at zero wheel travel. The curve for LF wheel travel versus toe intersects the x-axis at 0.05 degrees. You input 0.1 total toe, which is left toe plus right toe. Caster intersects at 4.0 degrees. Camber intersects at -0.5 degrees. 5. From From the the File menu, select Exit, and then select Exit, don’t save. Adams/Chassis returns to the main window.

Analyzing the Effect of Design Changes 1

Analyzing the Effect of Design Changes


Overview In this chapter, you modify model components to analyze the effects of design changes. You will modify tie-rod geometry and bushing stiffness. This chapter contains the following sections: • Inspecting Data Elements • Analyzing the Effect of Changes to Tie-Rod Geometry • Running a Compliance Analysis • Analyzing the Effect of Changes to Bushing Stiffness

The tutorial takes about 45 minutes to complete.

Analyzing the Effect of Design Changes 3 Inspecting Data Elements

Inspecting Data Elements Before you modify the example data, you will first focus on the different data elements in the vehicle configuration files. Adams/Chassis has a set of utilities that gives you visual access to the XML subsystem. You use the property editor edit or to gain quick access to every data element in your model.

To inspect data elements: 1. Sele Select ct the the Build mode

.

2. In the the toolb toolbar, ar, select select achassis_gs_front_sys. The property editor allows access to all the vehicle data, as shown below.

4 Getting Started Using Adams/Chassis Analyzing the Effect of Changes to Tie-Rod Geometry

Analyzing the Effect of Changes to Tie-Rod Geometry In this section, you modify the front suspension tie-rod geometry and analyze th e effect of the changes, as outlined next: • Modifying Tie-Rod Geometry Hardpoints • Running an Analysis • Plotting Analysis Results

Modifying Tie-Rod Geometry Hardpoints To modify tie-rod geometry hardpoints: 1. In the the treevi treeview, ew, expa expand nd achassis_gs_front_suspension, and then expand Hardpoints. 2. Sel Select tierod_outer. 3. In the the box box comm common on to to tierod_outer and Left Z, enter 548. 4. Sel Select Save As. The Select File window appears. 5. At the bottom bottom of the the window, window, in the File name text box, enter achassis_gs_front_suspension_new.xml. 6. Sel Select Save. A dialog box appears and asks if you want to update references to this data in the system file. 7. Sel Select Yes. The .xml file you just created appears in the treeview.

Note:

These changes will only be in effect during this session since you are not saving the system file.

Running an Analysis You now run an anal ysis on the modified tie rod to assess the effect of the changes to its geometry. geometry.

To run an analysis: 1. From From the tool toolbar bar,, select select Test mode. 2. In the the bookshe bookshelf, lf, double-click double-click Front Ride Motion. 3. In the the propert property y editor, editor, select select Front Auto-Alignment and set the following: 4. Total Toe to 0.1 5. Avg. Caster to 4.0 6. Avg. Camber to -0.5

Analyzing the Effect of Design Changes 5 Analyzing the Effect of Changes to Tie-Rod Geometry

7. Select lect Build and Run Selected Events . Adams/Chassis runs the analysis and, in the Adams run Python window, shows you the analysis steps. 8. When the the analysis analysis is complete, complete, close close the window. window.

Plotting Analysis Results To plot the analysis results: 1. From From the toolb toolbar, ar, selec selectt the Review mode. 2. In the the treev treeview, iew, select select fingerprint_1. 3. Clear Clear the the select selection ion of of achassis_gs_front_sys_fride by clicking the checkbox under Plots. 4. Veri Verify fy tha thatt Overlay data of same events is selected. 5. Select lect Execute Selected Plots. The overlay plot shows the effect of the new ti e-rod geometry (see Fi Figu gure re 9). The change made the toe curve more vertical. Later in this guide, you analyze how that change affects full-vehicle performance.

6 Getting Started Using Adams/Chassis Analyzing the Effect of Changes to Tie-Rod Geometry

Figure 9

Plot of Modified Tie-Rod Geometry

6. Exit the Adams/PostP Adams/PostProces rocessor sor without without saving the plots. plots. 7. Return Return to Adams/ Adams/Cha Chassi ssis. s.

Analyzing the Effect of Design Changes 7 Running a Compliance Analysis

Running a Compliance Analysis In this section, you modify the compliance of the front suspension, run a compliance analysis, and examine the analysis results. • Starting a New Fingerprint • Running an Analysis • Animating the Model • Creating a Report • Plotting Analysis Results

Starting a New Fingerprint To start a new fingerprint: 1. From From the toolb toolbar, ar, selec selectt the Test mode. 2. From From the toolb toolbar, ar, selec selectt the New Fingerprint tool

.

Running an Analysis In this analysis you will model a series of loads applied to the suspension. This will enable you to calculate various suspension compliances.

To run an analysis: 1. Make Make sur suree that that fingerprint_2 is selected in the treeview. 2. In the book bookshe shelf, lf, expan expand d Suspension. 3. From the list in the bookshelf, bookshelf, doubledouble-click click Front Compliance. 4. In fingerprint_2, select achassis_gs_front_sys_fcomp. 5. Sele Select ct the the Build and Run Selected Events tool. 6. When the the analysis analysis is complete, complete, close close the window. window.

Animating the Model You animate the model to see the effects of the analysis.

To animate the model: 1. From From the toolb toolbar, ar, selec selectt the Review mode. 2. Select lect fingerprint_2 in the treeview. 3. Sele Select ct the the Animate tool. 4. On the the menu menu toolbar, toolbar, select the Play tool.

8 Getting Started Using Adams/Chassis Running a Compliance Analysis

5. After the suspens suspension ion goes through through a complete complete animation, animation, select the Pause tool. 6. Exit Adams/PostP Adams/PostProcess rocessor or and return return to Adams/Chassis Adams/Chassis..

Creating a Report You can create a report for the front compliance analysis. The analysis consisted of several 2-second subevents where forces were applied at various points and in various directions on the wheel. The report tabulates the results of the subevents and calculates different front wheel compliances.

To create a report: 1. In th the Review mode, verify that Reports is selected. 2. Sel Select Execute Selected Reports tool

.

Adams/Chassis creates the report and opens it in your default text editor. 3. After viewing viewing the the report, report, exit the the report report window. window.

Plotting Analysis Results To plot the analysis results: 1. In th the Review mode, make sure Plots is selected. 2. Sel Select Execute Selected Plots. Adams/PostProcessor displays a series of plots with force/moment versus displacement/rotation, as shown in Fi Figu gure re 10.

Analyzing the Effect of Design Changes 9 Running a Compliance Analysis

Figure 10

Compliance Test Plots

3. Exit Adams/PostP Adams/PostProces rocessor sor without without saving the the plots. 4. Return Return to Adams/ Adams/Cha Chass ssis. is.

10 Getting Started Using Adams/Chassis Analyzing the Effect of Changes to Bushing Stiffness

Analyzing the Effect of Changes to Bushing Stiffness You now increase the stiffness rate for the front lower control arm bushing and view the results, as explained next: • Modifying Bushing Stiffness • Running an Analysis • Plotting Analysis Results

Modifying Bushing Stiffness To modify the bushing stiffness: 1. From From the toolb toolbar, ar, sele select ct the Build mode. 2. Make Make sure sure achassis_gs_front_suspension_new is selected. 3. In th the property editor, select the Connectors tab. A table of bushings appears. 4. Sel Select lca_front and then click in the Left_K-X box. 5. Chan Change ge the the Left _K-X stiffness for the Spring Rate to 6.450E+04. Since this is symmetrical, the right side also changes.

Running an Analysis To run the analysis: 1. From From the toolb toolbar, ar, sele select ct the Test mode. 2. Doub Double le-c -cli lick ck Front Compliance to add a new event to the fingerprint. 3. Sel Select Build and Run Selected Events .

Plotting Analysis Results To see the effect of increasing the bushing’s stiffness, you now plot the analysis results.

To plot analysis results: 1. In th the Review mode, make sure Plots is selected for fingerprint_2. 2. Sel Select Execute Selected Plots. The figure below shows the resulting plots. The plots show that your design change affected steer compliance (toe change per unit force) and lateral compliance. For example, in the plot named LF Parallel Lat Force vs. Toe, the the overall toe change is less than the toe change.

Analyzing the Effect of Design Changes 11 Analyzing the Effect of Changes to Bushing Stiffness

Figure 11

Compliance Test Plots (Modified)

3. Exit Adams/PostP Adams/PostProces rocessor sor without without saving the the plots. 4. Return Return to Adams/ Adams/Cha Chass ssis. is.

12 Getting Started Using Adams/Chassis Analyzing the Effect of Changes to Bushing Stiffness

Working with Full-Vehicle Models 1

Working with Full-Vehicle Models


Overview In this chapter, you work with a full-vehicle model and perform full-vehicle analyses. This chapter contains the following sections: • Setting Up a Full-Vehicle Model • Performing a Swept Steer Analysis • Performing a Constant Radius Analysis • Reviewing the Effects of the Tie-Rod Geometry Change • Optimizing Full-Vehicle Handling

The tutorial takes about one hour to complete.

Working with Full-Vehicle Models 3 Setting Up a Full-Vehicle Model

Setting Up a Full-Vehicle Model In this section, you set up a full-vehicle model.

Loading a Full-Vehicle Model To load a full-vehicle model: 1. In the Build mode, select the Load Model

button.

2. Select lect achassis_gs_full_sys.xml from the achassis_gs database.

Creating a New Fingerprint To create a new fingerprint: 1. From From the toolb toolbar, ar, selec selectt the Test mode. 2. From From the toolb toolbar, ar, selec selectt the New Fingerprint tool

.

4 Getting Started Using Adams/Chassis Performing a Swept Steer Analysis

Performing a Swept Steer Analysis When you perform a swept steer analysis, Adams/Chassis applies a steering wheel input to your model and stops when it reaches the specified lateral acceleration.

Running the Analysis To run the analysis: 1. In the test mode, make make sure the new fingerprint fingerprint you created created is selected selected in the treeview. treeview. 2. From From the booksh bookshelf elf,, expand expand Full Vehicle and then expand Handling Analyses. 3. Doub Double le-c -cli lick ck Swept Steer. 4. In the the treevi treeview, ew, sele select ct achassis_gs_full_sys_swpt, and then Build and Run Selected Events .. 5. After the event event is complete, complete, close close the command command window. window.

Animating the Model To animate the model: 1. Sele Select ct the the Review mode. 2. Select the swept swept steer event event in the treeview, treeview, and and then select select Execute Selected Animations.. 3. Play the animation, exit Adams/PostProcessor, Adams/PostProcessor, and then return to the Adams/Chassis window. window.

Working with Full-Vehicle Models 5 Performing a Constant Radius Analysis

Performing a Constant Radius Analysis One of the most useful full-vehicle analyses is the constant radius analysis. You can use this analysis to measure the steady-state performance of your vehicle and calculate such measures as understeer and roll gradient. In this section, you do the following: • Running the Analysis • Animating the Model • Creating a Report • Plotting Analysis Results

Running the Analysis To run the analysis: 1. From the the Test mode booksh bookshelf, elf, expand expand Full Vehicle, expand Handling Analyses, and then double-click Constant Radius . 2. In the the property property editor, editor, in the Turn radius text box, enter 60.0.

Note:

The constant radius event turns bold in the treeview to indicate that changes have been made.

3. Select the constan constantt radius event event in the treeview treeview and then then Build and Run Selected Events . 4. When the event event is complete, complete, close close the command command window. window.

Animating the Model To animate the model: 1. In the Review mode, select the constant radius event, and then select Execute Selected Animations. 2. Return Return to the Adams/Chass Adams/Chassis is window. window.

Creating a Report You now create a report to view the t he numerical results of the analysis. You You can use numerical results in optimization and design sensitivity studies.

To create a report: 1. In the Review mode, make sure that the correct fingerprint is selected in the treeview. 2. Veri Verify fy tha thatt Reports is selected.

6 Getting Started Using Adams/Chassis Performing a Constant Radius Analysis

3. Sel Select Execute Selected Reports. Adams/Chassis creates the report. When reviewing the report, focus on the section named Understeer Budget. This section lists the relative contributions of different subsystems to understeer, and can help point out which parameters you can modify to cause the greatest change in understeer. 4. Exit Exit the repo report rt window window..

Plotting Analysis Results To plot the analysis results: 1. In th the Review mode, select Plots. 2. Sel Select Execute Selected Plots. Adams/PostProcessor displays a series of plots, as shown in Fi Figu gure re 12. 3. Return to the Adams/Chass Adams/Chassis is window. window.

Figure 12

Constant Radius Plots

Working with Full-Vehicle Models 7 Reviewing the Effects of the Tie-Rod Geometry Change

Reviewing the Effects of the Tie-Rod Geometry Change Now you review the effects of the tie-rod geometry change to see how that change affects the understeer. Remember that in Analyzing the Effect of Changes to Tie-Rod Geometry, Geometry, the change made t he toe curve more vertical. In this section, you do the following: • Performing an Analysis • Plotting Results of Both A nalyses • Comparing Reports

Performing an Analysis You create a new event, modify the turn radius, and run another analysis. You later compare this analysis to the analysis you performed in Performing a Constant Radius Analysis.

To perform an analysis: 1. Sele Select ct the the Build mode. 2. In the treeview, treeview, select select the the front suspen suspension. sion. 3. In the the property property editor, editor, select select the the Hardpoints tab. 4. Select lect tierod_outer, and in the Left-Z column, enter 548. 5. Sele Select ct the the Test mode. 6. In the the bookshe bookshelf, lf, doubledouble-click click Constant Radius . 7. Enter 60.0 for Turn radius. 8. Make sure the constant constant radius radius event is selected selected in the treeview, treeview, and then Build and Run Selected Events. 9. When the event event is complete, complete, close close the command command window. window.

Plotting Results of Both Analyses To plot: 1. In the Review mode, select both constant radius analyses. 2. In the property property editor, editor, make make sure that Overlay Plots/Reports of Same Events is checked. 3. Select lect Execute Selected Plots. 4. Close Close the comm command and windo window. w. The first plot shows that modifying the tie-rod geometry had an effect on steering wheel angle versus lateral acceleration.

8 Getting Started Using Adams/Chassis Reviewing the Effects of the Tie-Rod Geometry Change

Figure 13

Constant Radius Comparison Plots

Working with Full-Vehicle Models 9 Reviewing the Effects of the Tie-Rod Geometry Change

5. Return Return to Adams/ Adams/Cha Chass ssis. is.

Comparing Reports To look at the numerical data associated with the analyses, you generate a second report and compare it to the one you generated in Creating a Report.

To compare reports: 1. Create a report report for the second second constan constantt radius event. event. 2. In the property property editor, editor, make make sure that Overlay Plots/Reports of Same Events is checked. 3. Compar Comparee the two two repor reports ts (achassis_gs_full_sys_cnrd (achassis_gs_full_sys_cnrd and achassis_gs_full_sys_cnrd_2). achassis_gs_full_sys_cnrd_2 ). The front roll steer in the second report is less than the roll steer in the first report. Roll steer is approximately toe change versus roll angle, and because the tie-rod geometry modification caused a more vertical toe curve, the roll steer has been reduced. Consequently, the understeer gradient is also reduced.

10 Getting Started Using Adams/Chassis Optimizing Full-Vehicle Handling

Optimizing Full-Vehicle Handling In this section, you modify vehicle parameters to try to achieve a specific numerical analysis result. For instructional purposes, you will use the target value of 2.4 deg/g for the understeer gradient.

To optimize full-vehicle handling: 1. Modify the tie-rod geometry just as you did did in Analyzing the Effect of Changes to Tie-Rod Tie-Rod Geometry. 2. Generat Generatee report reports. s. 3. Repeat this this process process until until you achieve achieve the target target value.

Working with Leaf Springs 1

Working with Leaf Springs


Overview Adams/Chassis supports two types of leaf springs: SAE 3-link and beam element. This chapter introduces you to the different types of leaf springs and contains two tutorials for modeling leaf springs in Adams/Chassis. • Working with SAE 3-Link Leaf Springs • Working with Beam Element Leaf Springs

Working with Leaf Springs 3 Working with SAE 3-Link Leaf Springs

Working with SAE 3-Link Leaf Springs When you work with 3-link leaf springs, you use the VisEdit Property Spring Tab to display and edit rotation spring and second stage rates, as shown Fi Figu gure re 14. The next two sections explain the data displayed in the table.

Figure 14

Adams/Chassis Dataview Table

4 Getting Started Using Adams/Chassis Working with SAE 3-Link Leaf Springs

Rotational Spring Rates • KT X = Longitudinal twist stiffness of that section (front or rear) of the spring. It is important for

roll stiffness. • KT Y = Lateral bending stiffness of that section (front or rear) of the spring. It is important for

the lateral stiffness of the suspension. Vertical bending stiffness of that section (front or rear) of the t he spring. This value is • KT Z = Vertical important since it defines the spring rate of the spring. • TO Z = The torque applied to the interleaf bushings (that is, front-to-middle link and middle-to-

rear link). This value is important in defining the spring rate of the leaf spring.

Second Stage Rates • If the vehicle has a second stage (auxiliary leaf), Adams/Chassis models the second stage as a

single-component force (SFORCE ( SFORCE)) between the body and the axle. • You can enter a simple linear rate (denoted by a positive value) or a nonlinear rate.

SAE 3-Link Leaf Spring Model Tutorial This tutorial explains how to select the files associated with 3-link beam elements, integrate them i nto a rear suspension, and run an analysis and view the results. Note that you will use the model that you create here in next tutorial, Beam Element Leaf Spring Model Tutorial. In the Beam tutorial, you will integrate a beam element spring in place of the 3-link leaf spring. The tutorial takes about one hour to complete.

Loading Example Vehicle Database and System File In this section, you will copy over an example vehicle database that uses a hotchkiss rear supension for study. 1. From From the the Utilities menu, select Database Utilities. 2. Sele Select ct the the Find tool next to the Vehicle Database text box. Choose the big_truck.vdb database by double-clicking the selection and selecting OK in the Selection dialog box.

Hint:

The path is: \achassis\examples\vehicles\big_truck.v \achassis\examples\vehicles\big_truck.vdb db

3. Sel Select Copy Database to Working Directory . 4. Sel Select OK at the prompt, and then close the Database Utilities window. 5. Sele Select ct the the Load Model button. 6. In the the Select Select File File window, window, select select big_truck.vdb for the Registered Database.


7. Select lect big_truck_rear_sys.xml, and then select Open.

Viewing Leaf Spring Data Before you run the simulation, view the data in the VisEdit Property Editor.

To view the data: 1. In the the treevi treeview, ew, selec selectt big_truck_rst.. 2. In the the property property editor, editor, select select the the Springs tab as shown below.

6 Getting Started Using Adams/Chassis Working with SAE 3-Link Leaf Springs

3. View View the the data data..

Figure 15

Leaf Spring Visual Editing Panel


Running an Analysis To run an analysis: 1. Sele Select ct the the Test mode. 2. In the book bookshe shelf, lf, expan expand d Suspension, and the double-click Rear Ride Motion. 3. Select the the rear ride motion motion event event in the treeview, treeview, and then then Build and Run Selected Events . 4. When the event event is complete, complete, close close the command command window. window.

Animating the Model To animate the model: 1. Sele Select ct the the Review mode. 2. In the the treev treeview, iew, select select big_truck_rear_sys_rride. 3. Select lect Execute Selected Animations. 4. From the dashboard, dashboard, select the Play tool

.

5. After the suspensi suspension on goes through through a complete complete animation, animation, select the Pause tool

.

6. Exit Adams/PostPr Adams/PostProcess ocessor, or, and return to Adams/Chas Adams/Chassis. sis.

Modifying the Leaf Spring You modify 3-link leaf springs using the same methods you have already learned for suspensions and full vehicles: modify properties in the property editor, editor, save the changes as a new file, and compare the results.

8 Getting Started Using Adams/Chassis Working with Beam Element Leaf Springs

Working with Beam Element Leaf Springs A beam element leaf spring model is a series of small parts connected by beams based on first principles. Adams/Chassis provides a Leaf Spring Preprocessor in which you can quickly and efficiently prepare the beam element leaf spring. You You run the Preprocessor whenever you change the leaf properties. The next sections explain more about working with beam element leaf springs and provide a tutorial that steps you through the process of adding and analyzing leaf springs: • Beam Element Leaf Spring Model Tutorial • Viewing and Editing Beam Element Leaf Springs

The following is a flowchart that shows how to generate a model containing beam element leaf springs. The tutorial, Beam Element Leaf Spring Model Tutorial, runs you through the steps needed to generate the model in Adams/Chassis.

Working with Leaf Springs 9 Working with Beam Element Leaf Springs

Gather Data Measure the leaf spring geometry in the free position. Measure the mass of the shackle. Measure the bushing rates of the three leaf spring bushings. Measure the height of the leaf spring leaf

Enter Data

.ltf

Enter data in the leaf spring .ltf file.

Generate Model Run Leaf Preprocessor to exercise leaf model to design position. Adams/Chassis creates a leaf .py file. It contains parts, markers, beams, and so on, that define the leaf spring. Turn off the 3-link leaf spring and turn on the beam element leaf spring

Figure 16

Flowchart for Working with Beam Element Leaf Spring Models

Viewing and Editing Beam Element Leaf Springs Just as for the 3-link leaf spring, Adams/Chassis provides you with the ability to view and edit the information defining the leaf spring. For beam springs, the editor is the Leaf Preprocessor. The next sections explain the information about beam element leaf springs that you can view and edit in the Leaf Preprocessor. • General Leaf Spring Information • Axl Axle e • Shackle • Geometr y


• Leaf Eyehook • Bushing • Leaf Profile

General Leaf Spring Information You can view and edit the following general information about the beam element leaf spring: • Number of leaves - The number of leaves in the model. • Frictional coefficients - Leaf-to-leaf friction. • Impact exponent - Level of impact. • Leaf spring mounting - Where the leaf spring will be mounted in t he vehicle. Used mainly for

part numbering. order.) • Fitting algorithm - Polynomial fitting of the leaf profile. (Generally, you use second order.)

Axle For the axle, you can specify: • Extra mass on dummy axle - The extra mass used to assemble the spring pack and connect it to

the axle. • Reference marker to leafpack -The z height of the reference marker for the axle with respect to

the coordinate system used to define the profiles. • Axle mount type - Either underslung or overslung, as shown in the following figure. If the

leaves are mounted above the axle, it is overslung. If the leaves are mounted below the axle, it is underslung. • Front and rear inactive lengths - Sections of the leaf spring regarded as rigid near the point

x=0.0. • Reference marker height at design load - The z height of reference marker used to stop the

simulation. Once the axle reaches this point, it is at design load.


Figure 17

Illustration of Underslung and Overslung Leaves

Shackle For the shackle, you can specify: • Shackle length - The physical length of the shackle part, from eye center to eye center, specified

in millimeters. • Shackle mass and inertia - The mass and inertial properties of the leaf spring shackle, in the

units shown. • Shackle location - Whether the shackle is at the front or rear of the leaf spring pack. • Shackle position - Whether the shackle is used in tension or compression. If the leaf eye is

below the shackle-to-body point, the link is in compression; if the leaf eye is above the shackleto-body point, the link is in tension.

Geometry For geometry, geometry, you indicate points in space where t he leaf springs will be constructed. Enter the x, y, and z positions for both the front and rear chassis connection points. You You must do this for both LEFT and RIGHT springs. You need another entry for the chassis contact points if you define an auxiliary leaf spring in the template. This information is formatted such that it can be taken directly from the Adams/Chassis templates.


• Front leaf eye bushing - Corresponds to Points 1 and 2 in the subsystem file. • Shackle to frame - Corresponds to Points 20 and 21 in the file.

Leaf Eyehook For the leaf eyehook, you can specify: • Front and rear eyehook inner diameter - Diameter of the inside of the eyehook. • Front and rear eyehook shape - The shape of the eyehook, as shown below. Downturned Eyehook

Berliner Eyehook

Figure Figure 18

Upturned Eyehook

Eyehook Eyehook Shapes Shapes

Bushing For bushings, you specify the translational and rotational spring and damping rates. You You can choose to call the bushing spring rates from the subsystem file by turning on the flag in the lower right corner of the Leaf Preprocessor. Calling the rate information from the subsystem file reduces bookkeeping, and allows you to modify the bushings for variation studies. The leaf-to-leaf bushings keep the leaves from moving laterally or twisting from each other. They should have rather large values (~1.0 E+9 for translational rates and ~1.0 E+7 for rotational rates).

Leaf Profile • Auxiliary leaf flag - Whether the leaf is defined as an auxiliary leaf (1) or not (0). The leaf flag

does not apply to Leaf 1, because Leaf 1 is always the leaf with eyehooks. The auxiliary leaf should generally be the last leaf you specify. An auxiliary leaf is located on top of the leafpack and, after the leaf spring has been compressed to a point, the auxil iary leaf contacts the chassis and augments the spring pack. • Z-offset - The sum of all previous leaf thickness and gap distances. • Leaf length - The length of the front and rear sections of the leaf from the point x=0.0 defined in

the profile. • # of elements (<=45) - The leaf being defined will be broken up into discrete sections, each of

which will be modeled using an Adams BEAM element (see the BEAM statement in the online help for Adams/Solver.) Adams/Solver.) • Seat thickness and width - Thickness (z-direction) and width (y-direction) of the leaf being

defined at the point X=0.0. Young’s modulus of elasticity (Emod), S hear modulus of elasticity • Emod, Gmod, density - Young’s (Gmod), and density of leaf spring material. U sed to define the beam statements and part masses.


• ASY, ASZ - Correction factor for shear deflection in the y (ASY) and z (ASZ) directions,

according to Timoshenko beam theory. • Damping ratio - The ratio for calculating the structural damping matrix for the Adams beam.

Adams/Solver multiplies the stiffness matrix by this value to obtain the damping matrix. • X column - The position along the arc length of the spring, which is determined by flattening the

spring. Negative values are forward with respect to the vehicle. t op of the spring at the points on the spring that correspond to x. • Z column - The curvature of the top • Thickness column - The Thickness column defines the thickness of the leaf at each x value. The

column is flexible about the amount of data entered. You You can define data only at desired points or at all points. The only restriction is that you enter at least one value. Adams/Chassis processes the data in the following way: • Empty points between defined points are linearly interpolated. • Empty points at the ends of the spring (outside of defined points) are held constant at the last

defined value. • Number of contact points - Used to keep the leaves from passing through each other as they

deflect, in effect modeling the physical contact of the top of the current leaf with the bottom surface of the one above it. • Gap distance - The gap between the leaf and the one above it.

Tips for Using Beam Element Leaf Spring Models • Increasing the thickness of the leaves increases the ride rate. • Increasing the number of contacts between the leaves results in an increase in computational

time. t o move the leaf spring to design position: • You define two reference markers that are intended to •

The reference marker height marker height at design load is the height of the axle center at design.

marker to leafpack is the distance from the reference marker to the bottom • The reference marker to of an overslung leaf or the top of t he underslung leaf. A positive number indicates overslung, while a negative number indicates underslung. When Adams/Chassis builds the leaf spring, it exercises the model until the reference marker to leafpack reaches the height, which is the sum of the two heights. The leaf will be in its deformed position.

Beam Element Leaf Spring Model Tutorial This tutorial creates a beam element leaf spring and incorporates it into a rear suspension. It shows you how you use the Leaf Spring Preprocessor to generate all the necessary flexible parts (beam elements, parts, markers, and so on) needed to define the leaf spring in your model. The process for creating a model containing a beam element leaf spring includes gathering data and entering the data in an.ltf an.ltf file. For this tutorial, we’ve gathered t he data for you and provided you with example.ltf. a sample .ltf file called example.ltf.


This tutorial builds upon the model you created in the tutorial earlier in this chapter, SAE 3-Link Leaf Spring Model Tutorial. Therefore, be sure to run through that tutorial first. The tutorial takes about one hour to complete.

Viewing the Leaf Spring example.ltf, which contains a profile of a leaf spring. The leaf spring contains You will use the file, example.ltf, four leaves.

To run the Leaf Preprocessor: 1. Copy example.ltf located in /examples/ltf into the springs.tbl folder in the big_truck database in your working directory. The data in example.ltf appears in the Leaf Spring Preprocessor, P reprocessor, as shown in the following figure. 2. From From the the Utilities menu, select the Leaf Spring Editor tool

.

3. Sele Select ct the the Find tool for the .ltf text box. 4. Double-click Double-click the database database to which you copied the example example file, double-click double-click springs.tbl, and then select example.ltf .


General properties about the entire leaf

Information about each leaf in the spring

Figure 19

Plot of leaf springs

Leaf Spring Preprocessor


Note:

If you modify the leaf spring, you must save the data before you select GO.

5. To view a plot of each leaf in the file, select select each of the leaf tabs in the lower portion of of the Preprocessor. Adams/Chassis highlights the selected leaf in the plot to the right. 6. View the general information about the the leaf spring by selecting each tab at the top of the Preprocessor. For explanations of the information displayed in each of the tabs, see Viewing and Editing Beam Element Leaf Springs.

Running Makeleaf To implement the leaf spring into your Adams/Chassis model, you must first run the Leaf Spring example.py, which Preprocessor (Makeleaf). The Leaf Spring Preprocessor generates a file called example.py, contains the beam elements, parts, markers, and so on, needed to define the leaf spring in your model.

To run Makeleaf from the Leaf Spring Preprocessor: 1. Sel Select GO. 2. In the command command window, window, at the prompt, prompt, select select Enter. 3. To return return to the Adams/Chas Adams/Chassis sis main window, window, select select Exit.

Note:

The leaf spring processor can also be executed from the command line by issuing the following command: achassis_script -makeleaf example.ltf (where achassis_script" is the command to start up Adams/Chassis) "achassis_script"

Incorporating the Beam Element Leaf Spring into You r Model To incorporate the spring into your model: 1. In the the treevi treeview, ew, sele select ct big_truck_rst. 2. In the property property editor, editor, select select the Springs tab. 3. Doub Double le clic click k on sae3link_leafspring. 4. Under “Select “Select Current Current Property Property”, ”, select select the Create New button. 5. In the “Enter “Enter Name Name and Type” Type” dialog dialog box, select select SpringLeaf under Type. Enter “beam_leaf ” in the Name field. 6. Select Select the the newly newly creat created ed beam_leaf property. 7. Sele Select ct the the Find tool next to the property file, and then select example.py.


8. Select lect Save as along the bottom, and save your new rear subsystem file as hotch_beam.xml. 9. Select lect Yes to update references in the system file.

Running an Analysis and Animating It To run an analysis of the model with a beam element leaf spring: 1. In the Test mode, expand Suspension in the bookshelf. 2. Doub Double le-c -clic lick k Rear-Ride Motion. 3. Select the event event in the the treeview, treeview, and and then Build and Run the Selected Event . Note that this analysis takes significantly longer to run than the 3-link beam analysis because the model is more complex. 4. When the analysis analysis is is completed, completed, close close the command command window.

To animate the model: 1. Switc Switch h to to the the Review mode. 2. Select the the event in in the treeview, treeview, and and then select select Execute Selected Animations. 3. Play the animat animation ion.. In the animation, you see many more elements than you saw in the previous 3-link leaf spring model. Adams/Chassis modeled each leaf spring as a series of beam elements. 4. Return Return to the Adams/Chass Adams/Chassis is window. window.

Analyzing Effects of Leaf Spring Design Changes Now you’ll use the model you created to examine the e ffect of leaf spring thickness on wheel rate. First, you’ll change the thickness of Leaf 1 of the leaf spring, and then you’ll run an analysis and compare t he results of analysis with the previous analysis to see the effect of the different thicknesses.

To change the leaf spring thickness: 1. From From the the Utilities menu, select the Leaf Spring Editor . 2. Load Load the file file example.ltf. 3. Select lect Leaf 1, and change its thickness to 13 mm by entering 13 in the Thickness column (third column in the middle table). For more information about the Thickness column, see Leaf Profile. 4. Select lect Save as, and change the name of your modified file to example2.ltf . 5. Rebuild Rebuild the leaf model model by by selecting selecting GO. 6. Sele Select ct the the rear suspension and select the new spring property. 7. Select lect Save as along the bottom, and save your new rear subsystem file as hotch_beam2.xml.


8. To update update references references in in the system system file, select select Yes. 9. To save save the the system system file, file, select Save.

To run an analysis: 1. Switch Switch to the Test Test mode mode.. 2. Double Double-cl -click ick the Rear Ride Motion event. 3. Sel Select Build and Run Selected Events . 4. When the analysi analysiss is complete, complete, close close the the window. window.

To plot the analysis results: 1. In the Review mode, select the two rear ride motion analyses in the fingerprint tree. 2. Veri Verify fy tha thatt Overlay Plots/Reports of Same Events is selected. 3. Sel Select Execute Selected Plots. 4. In the treeview treeview of Adams/Pos Adams/PostProces tProcessor, sor, select select p03_Rear_Ride_motion. Now you’ll view plots that show the effect of modifying Leaf 1’s thickness from from 8 mm to 13 mm on wheel rate. 5. Exit Adams/Post Adams/PostProces Processor sor and Adams/Ch Adams/Chassis assis.. As you can see from this tutorial, modeling with beam element leaf springs requires one additional modeling step when investigating design changes.

Integrating Control Systems in Your Model 1

Integrating Control Systems in Your Model


Overview This tutorial explains how to integrate a control system into your model. It uses the example of adding an ABS controller to a brake model to improve the braking performance of the vehicle so that the wheels do not lock up. It explains: • About Adding Control Systems • Loading Example Data Files • Running an Open-Loop Braking Event • Creating the Control System Utility • Building and Running the Model with Control System Included • Analyzing Effect of the Control System

The tutorial takes about one hour to complete.

Integrating Control Systems in Your Model 3 About Adding Control Systems

About Adding Control Systems External controllers are becoming more and more common in vehicles today, and it is sometimes necessary to include them in your model to accurately predict how your vehicle will behave under various conditions. Therefore, we’ve added the ability for you to add external control systems into your Adams/Chassis model. Adams/Chassis standard templates have logic for control systems built directly into them. The logic is represented as lists of standard control system inputs and outputs. We’ve constructed these lists so they support some of the most common control systems in use today. You You can attach the inputs and outputs represented in these lists to an external control system with no customization to the Adams/Chassis preprocessing templates. And, with customization, you can connect anything else in your Adams/Chassis model to the control system. You represent the control system as FORTRAN or C code. The code must contain a main calling program that serves as the interface to your Adams/Chassis model. The calling program's parameter list must adhere to strict requirements. For more information about control system subroutines, see the Adams/Chassis online reference. The following tutorial takes you through the process of adding a simple ABS brake system to your model. You will set up the inputs and outputs to this control system, create a new custom Adams/Solver library that contains the ABS system, and compare your model's performance in a braking maneuver with and without the controller. controller.

4 Getting Started Using Adams/Chassis Loading Example Data Files

Loading Example Data Files In this section, you load the component example data files for your Adams/Chassis session.

To load files: 1. In the the Build Build mode, mode, from from the the Utilities menu, select Database Utilities. The Database Utilities window appears. 2. In the Copy database database tab, tab, select select the the Find tool

next to Database to Copy.

3. In the Browse Browse for Folder Folder window, window, select select f_car.vdb, and then select OK . 4. The The path path is: is: \achassis\examples\vehicles\f_car.vdb . 5. Sel Select Copy Database to Working Directory . Adams/Chassis copies the f_car example database to your working directory. 6. Sel Select OK at the prompt and then exit the Database Utilities window.

To load example brake subsystem data: 1. Sele Select ct the the Load model tool, double-click f_car.vdb, double-click systems.tbl, and then open f_car_full_sys.xml. 2. Sel Select f_car_full_sys in the tree. 3. In the property property editor, editor, select select the Find tool for Brakes. 4. From the list list of databases databases in the Select Select File window, window, select shared_chassis_database. 5. Sel Select brake_simple.xml, select Open, and then select Apply in the property editor. 6. Save Save the the syste system m file. file. To learn more about the simple brake model, review the Brake System documentation in the Adams/Chassis online help.

Integrating Control Systems in Your Model 5 Running an Open-Loop Braking Event

Running an Open-Loop Braking Event In this section, you’ll run an open-loop braking event and then view the results. Before doing so, you’ll change the default preferences to generate road graphics.

To change preferences: 1. From From the the Edit menu, select Preferences. 2. In the the Preference Preferencess window, window, select select Use Road Graphics. 3. Select lect Save. 4. Go to the the Test mode.

To run an open-loop braking event: 1. In the book bookshe shelf, lf, expan expand d Full Vehicle, expand Braking Analyses, and then double-click Open Loop Braking. 2. In the tree, select select the open-loop open-loop braking braking event, and then then change Brake Pedal Force to 200 N. 3. Select lect Build and Run Selected Events. Adams/Chassis builds your model and runs it through an open-loop braking analysis. 4. When the the analysis analysis is complete, complete, close close the window. window. Now you’ll view the results of the open-loop braking event.

To animate the results: 1. In the the Review Review mode, select the open loop braking event in the tree. 2. Select lect Execute Selected Animations. Adams/PostProcessor animates the analysis. During the animation, note the severe braking in the maneuver. 3. After reviewing reviewing the animation, animation, exit exit Adams/PostProc Adams/PostProcessor essor..

To plot the results: 1. Plot the the analysis analysis by selectin selecting g Execute Selected Plots. 2. Use th the Display Next Page tool

to view the plots.

Review plots in the lower-left corner of page 3. Not ice the tire patch slip ratios for the rear tires are going to -100%, indicating wheel lockup.

6 Getting Started Using Adams/Chassis Creating the Control System Utility

Creating the Control System Utility To add the ABS controller to your model you use the Control System utility. Using the Control utility, you can add up to five control systems to your model. For each system, you will specify control system inputs, outputs, and supporting source code fil es. • Activating and Setting Up Control System Utility • Specifying Control System Inputs • Specifying Control System Outputs • Specifying Control System Libraries and Saving System Data

Activating and Setting Up Control System Utility To activate the Control System utility: 1. Return Return to the the Build Build mode mode.. 2. Sel Select f_car_full_sys, and in the property editor, select the Check box to the left of Controls. This makes the text box active and allows you to create a new controls file.

To set up the Control System utility: 1. Make Make sure sure to activ activate ate the the Controls subsystem by selecting the check box on the left. 2. Sele Select ct the the Find tool for Controls. 3. In the Select File window, window, select select the shared_chassis_database, and then open brakes_controls_abs.xml. 4. In the the propert property y editor, editor, select select Apply. 5. In the the treevi treeview, ew, sele select ct brakes_controls_abs. 6. Sele Select ct the the Controls tab. 7. In th the Name text box, verify that it is ABS_example. 8. In th the Subroutine Name text box, verify that it is ABS. 9. In th the Step Size text box, verify that it is .01. 10. Sele Select ct FORTRAN as the Code Type.

Specifying Control System Inputs Now you’ll specify the inputs to the control system. In the example abs.f that we’ve supplied, the input parameters to the subroutine are as follows: • Master cylinder pressure • Left front wheel omega (left front wheel rotational speed) • Right front wheel omega

Integrating Control Systems in Your Model 7 Creating the Control System Utility

• Left rear omega • Right rear omega

Note:

Control system inputs and outputs must be selected for them to appear in the subroutine's parameter list.

To specify control system inputs: 1. Sele Select ct the the Input tab. 2. Select lect Master Cylinder Pressure. 3. Sele Select ct the the Add

button to add the input to the Selected List.

4. To select the four wheel omega inputs at once, hold down the left mouse button, and and then highlight Wheel Omega FL through Wheel Omega RR . 5. Select lect Add

to add these four to the Selected List.

You have now selected the five subroutine inputs. Note that variable IDs and scale factors are present for each input. For these standard inputs, the necessary Adams/Solver VARIABLES are contained in the standard Adams/Chassis templates, and will be automatically added to your model when you include this control system. The scale factors are also the default for the standard list, and are associated with the default units for each input. If the source code is expecting a different unit than shown, you may have to modify the scale factor for one of the default inputs. For user factors, you must supply the variable ID and scale factor. You must then customize Adams/Chassis such that an Adams/Solver variable with your specified ID is included in your model.

Specifying Control System Outputs The four output parameters for this tutorial are: • Left front brake-line pressure • Right front brake-line pressure • Left rear line pressure • Right rear line pressure

To specify the control system outputs: 1. Sele Select ct the the Output tab. 2. Holding Holding down the the left mouse mouse button, button, highlight highlight Brake Line Pressure FL through Brake Line Pressure RR to select the four brake-line pressure outputs at once. 3. Select lect Add

to move these four to the Selected List.

8 Getting Started Using Adams/Chassis Creating the Control System Utility

The four outputs of the controller have now been selected. As with the inputs, the standard outputs have default units and scale factors. You may have to modify the scale factor or add a user output for different control systems. For user outputs, you must supply the variable ID, and customize Adams/Chassis such that the variable is included in your model.

Specifying Control System Libraries and Saving System Data In this section, you specify abs.f as your control system library and save it. The file abs.f is the only source file you need.

To specify a control system library and save it: 1. Copy Copy exam exampl plee abs.f . 2. To find find the top director directory, y, enter enter From the shell: achassis_top. 3. Copy /examples/f/abs.f to your working directory. 4. Sele Select ct the the Control Libraries tab. 5. Sele Select ct the the Find tool. 6. Sel Select abs.f . 7. Sel Select Open. 8. Sel Select Add

Note:

to move abs.f to the Control Library List.

For information on the format of control system libraries, see the Adams/Chassis online help.

Your control system specification is now complete. You’ll You’ll now save it.

To save the control system: 1. In the lower right corner, corner, select select Save as. 2. Sele Select ct the the f_car database in the upper left corner. Then double-click the 3. Enter abs_example.xml. 4. Sel Select Save. 5. Select to to update update reference reference in in system system file. file. 6. Sel Select Save as and enter f_car_abs.xml.

Controls.tbl folder.

Integrating Control Systems in Your Model 9 Building and Running the Model with Control System Included

Building and Running the Model with Control System Included You will now begin the process of integrating the control system into your model and performing an open-loop braking event.

To integrate the control system: 1. In the the Test Test mode, mode, selec selectt f_car_abs as your system file. 2. In the book bookshe shelf, lf, expan expand d Full Vehicle, expand Braking Analyses, and then double-click Open Loop Braking to add an additional event. 3. Make sure your your event parameters parameters are the the same as in the original model. model.

Note:

Ensure that the pedal force is 200.

4. Select lect Build and Run Selected Event . Adams/Chassis displays a message stating that the control system abs_example has been included in the model. During the build process, Adams/Chassis will compile and li nk abs.f nk abs.f to ABS_example.{so, sl, dll}. This library should reside in the working create a control library ABS_example.{so, directory.

Note:

In order for Adams/Chassis to compile and link the native ADAMS library, library, it must have access to both the FORTRAN and C compilers. If the compile or li nk process fails, it may be due to the fact that Adams/Chassis was launched from a command shell without the proper compiler settings (on Windows, executing the batch file "ifortvars.bat" located in the FORTRAN installation directory will set up the correct e nvironment for the compilers). For more information, refer to the hardware and software specifications included with your installation instructions, and on the MSC Adams Product Support Page. http://www.mscsoftware.com/products http://www.mscs oftware.com/products/adams_support.cfm /adams_support.cfm

10 Getting Started Using Adams/Chassis Analyzing Effect of the Control System

Analyzing Effect of the Control System To see the effects of the ABS control system: 1. Sele Select ct the the Review mode. 2. Activate Activate the plots for the original original and control-s control-system ystem analyses analyses.. 3. Sel Select Execute Selected Plots. You can now compare the plots to see the effect of the ABS system; the rear wheels do not lock with the ABS system activated.

Getting Started Using Adams/Chassis - MD Adams 2010

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