WS11-1 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation WORKSHOP 11 FLEX TUTORIAL

WS11-2 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation

WS11-3 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation Flex Tutorial ● In this workshop, you swap a rigid lower control arm with a flexible control arm in a suspension template. ● First, you need to change the memory for A/View and A/Solver to Huge. Windows: Start Menu  Programs  MSC.Software  MD R2 Adams  Adams Settings – Adams Solver and Adams View – Preferences – MemSize = Huge Unix: Right Click Adams Toolbar – Start Registry Editor - Adams Solver and Adams View – Preferences – MemSize = Huge Note: You need to start a new A/Car session after this change

WS11-4 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation ● Opening a subsystem To open a subsystem: 1. From the File menu, select Open. 2. Right-click the Subsystem Name text box, point to Search, and then select \subsystems.tbl. 3. Double-click TR_Front_suspension.sub. 4. Select OK. Flex Tutorial

WS11-5 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation Flex Tutorial ● To create the flexible lower control arm: 1. From the Adjust menu, point to General Parts, point to Rigid- to-Flex. 2. In the Current Part Name text box, Pick and select gel_lower_control_arm. 3. In the Modal Neutral File text boxes, point to the files LCA_left_shl.mnf, located in the database. Adams/Car displays the flexible bodies on top of the rigid bodies. You can see bodies in this configuration when the model is displayed in wireframe mode. Tip: If your model is not displayed in wireframe mode, type an uppercase S to see the model in wireframe mode.

WS11-6 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation Flex Tutorial ● Identify the attachments: 1. On the Status bar, right-click the Information tool stack, and then select the Model Topology by Parts tool. The Information window displays the topology map. 2. Scroll to the top of the Information window and look for gel_lower_control_arm, the associated list of attachments, and their corresponding parts.

WS11-7 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation Flex Tutorial PICTURE ● Associate all connections to flexible body using the Preserve Expression tab 1. Select the Move tab to highlight all connections. 2. Next select Preserve expression. 3. Click Apply and repeat for the other side.

WS11-8 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation Flex Tutorial ● A warning message appears to indicate that the flexible body can not be resized simply by moving the hardpoints any more.

WS11-9 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation Flex Tutorial ● To run an analysis with your suspension with flexible control arm: 1. Save the subsystem as TR_Front_Suspension_flex to the acar_training database. 2. Create the assembly ● From the File menu, point to New, and then select Full-Vehicle Assembly. ● Fill in the dialog box as shown next, and then select OK. ● Click on the folder icon in Front Susp Subsystem field, to use the present subsystem in memory for the full vehicle model.

WS11-10 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation Flex Tutorial ● Changing Modal Content ● By default, when you integrate an MNF into an Adams/Car template, Adams/Flex enables all the modes that were defined during the FEM modeling except the probable rigid body modes. It is important to have the right modal content in flexible bodies, because an MNF has more modes than are needed to simulate a particular response. ● To increase the efficiency of the simulations, you could disable any modes that do not contribute to the motion that your flexible part will undergo during the simulation. Be careful when disabling modes, because a disabled mode corresponds to a constraint to the part. Changing the modal content of a flexible body corresponds to a flexible body setup. In addition, sometimes, it is not possible to know the contribution of one particular model to the overall deformation of the flexible body.

WS11-11 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation Flex Tutorial ● You can manually toggle modes on or off. This gives you greater flexibility and helps you avoid potential problems. You can enable and disable modes in several ways: ● Individually, based on their mode number. ● As a group, based on their mode number or frequency. ● Through a table editor. The table editor also lets you define displacement and velocity initial conditions associated with every mode. ● Based on their strain energy contribution, but you can only do this after a successful analysis. For more information on this technique, see the Adams/Flex online help.

WS11-12 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation Flex Tutorial ● To disable individual modes: ● Some of the modes of the flexible lower control arms do not contribute effectively to the dynamic behavior of the entire system. We recommend that you disable them to reduce the computational effort and to improve the efficiency of the simulation. ● You must disable these modes for both the left and the right side because a left and a right MNF defines the flexible lower control arms. 1. Zoom in on the front suspension. 2. Right click the gel_lower_control_arm_flex, point to Modify, and then select modify icon. The Flexible Body Modify dialog box appears.

WS11-13 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation 3. Select Modal ICs. The Modify Modal ICs dialog box appears. 4. Hold down the Shift key, select modes 28 and 29, and then select Disable Highlighted Modes. 5. Close the Modify Modal ICs dialog box. 6. Repeat Steps 2 through 6, for the right lower control arm, ger_lower_control_arm_flex. (You could also just right-click the Flexible Body text box, point to Flexible Body, point to Pick, and from the screen select ger_lower_control_arm_flex.) 7. Close the Flexible Body Modify dialog box. Flex Tutorial

WS11-14 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation ● Performing a Full-Vehicle Analysis ● You are now ready to perform the full-vehicle analysis. After you perform the analysis, you can change the inertia modeling of the flexible body to compare the effect of the modal flexibility on the dynamics of the vehicle. ● To perform the full-vehicle analysis: 1. From the Simulate menu, point to Full-Vehicle Analysis, point to Open-Loop Steering Events, and then select Step Steer. 2. Set up the analysis as follows: ● Full-Vehicle Assembly: fveh_assy ● Output Prefix: tst ● End Time: 4 Flex Tutorial

WS11-15 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation ● Number of Steps: 400 ● Initial Velocity: 70 (take the default of km/hr) ● Gear Position: 3 ● Initial Steer Value:0 ● Final Steer Value: -45 ● Step Start Time: 1 ● Duration of Step: 1 ● Steering Input: Angle 3. Keep the defaults for Cruise Control (off) and Quasi-Static Straight Line Setup (on). 4. Select Apply, so the dialog box stays open for the analysis you will run in the next section. The SDI test rig applies to the assembly the inputs you specified and performs a dynamic analysis. Flex Tutorial

WS11-16 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation ● To change the inertia modeling: 1. Right click the gel_lower_control_arm_flex, point to Modify, and then select modify icon to bring up the Flexible Body Modify dialog box. 2. Select the Mode Manager tool. 3. Set Inertia modeling to Rigid body. 4. Select OK. 5. Close the Modify Flexible Body dialog box. 6. Submit another step steer analysis using the same inputs as before, but changing the output prefix to tst_rigid. Adams/Car analyzes the assembly. Flex Tutorial

WS11-17 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation ● Plotting Analysis Results ● In this section, you create a set of plots that show the behavior of your vehicle assembly and then review how the modal flexibility of the lower control arm affects the overall dynamics of the vehicle. ● To plot the results: 1. Launch Adams/PostProcessor. 2. From the Plot menu, select Create Plots. 3. Fill in the dialog box as shown next, and then select OK. Flex Tutorial

WS11-18 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation Flex Tutorial ● Figure shows an example. The flexible lower control arms cause the differences between the curves for the Yaw Rate of the vehicle. 4. View the plots shown next and then return to Adams/Car.

WS11-19 ADM740, Workshop 11, June 2007 Copyright  2007 MSC.Software Corporation