1. S6-1 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation SECTION 6 CREATING AND SIMULATING SUSPENSIONS

2. S6-2 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation

3. S6-3 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation ● In this section, you learn how to create a suspension assembly in Adams/Car. You also learn about the available suspension analyses and how to submit them. Creating and Simulating Suspensions

4. S6-4 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation ● What’s in this section: ● Creating Suspension Assemblies ● Half-Vehicle Analyses ● Suspension Parameters ● Creating Loadcases ● Warning Messages ● Files Produced by Analyses Creating and Simulating Suspensions

5. S6-5 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation ● An assembly consists of a single test rig and one or more subsystems (a test rig by itself is just a specialized subsystem). ● You create suspension assemblies in Standard Interface: from the File menu, point to New, and then select Suspension Assembly. In the dialog box, specify all the subsystems to be included in the assembly, as well as the test rig. ● If you use subsystems created from new templates, you need to make sure the communicators match up. Communicators are special variables defined at the template level to bring the subsystems together, and with the test rig, to create an assembly. In the template-builder mode, you can test the communicators to make sure they match with other templates (communicators are described in more detail in Section 11 – Communicators). Adams/Car displays warning messages in the Message window for communicators that are not matched when creating an assembly. Creating Suspension Assemblies

6. S6-6 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Creating Suspension Assemblies (Cont.) ● The picture below shows a suspension assembly containing a suspension and steering subsystem, and test rig. ● Because simulations are activated by test rigs, to perform a simulation, you must use an assembly.

7. S6-7 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Suspension Assembly Illustrated Suspension Steering (optional) Testrig Suspension Assembly

8. S6-8 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Half-Vehicle Analyses ● You can perform the following types of suspension analyses in Adams/Car: ● Parallel wheel travel - Both wheels move in unison. ● Opposite wheel travel - Wheels move out of phase. ● Roll and vertical force - Sweeps roll angle while allowing wheels to find their own vertical position because the total force on both wheels is held constant. ● Single wheel travel - One wheel fixed, while other moves. ● Steering - Motion applied to steering wheel or rack.

9. S6-9 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation For more information, see the Running Analyses section in the Adams/Car online help. Half-Vehicle Analyses (Cont.) ● Static load - Force or displacement applied at specified locations (wheel center, tire contact patch), with or without steering. ● External files: ● Loadcase - Essentially a selection of previous events. ● Wheel envelope - A parallel wheel travel while moving the steering to get the volume the wheels take up in all exercises. ● When performing a suspension analysis, Adams/Car uses the first second to bring the wheel centers to the lowest position, and then uses as many seconds as you specify steps, to move the suspension to the upper position. ● Dynamic Analysis - Apply test data to drive the test rig actuators and carry out dynamic analysis

10. S6-10 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Suspension Parameters ● Some of the default request outputs need information that is not available in the model. Therefore, you must supply this additional information. This information has no bearing on the outcome of the simulation, as it only affects some of the user-defined results (for example, the roll center, among others). ● Adams/Car stores the input in an array named Suspension Parameters, which you can find in the Standard Interface under Simulate  Suspension Analysis  Suspension Parameters. ● The values you must supply are: ● Loaded tire radius

11. S6-11 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Suspension Parameters (Cont.) ● Tire stiffness (user-entered or from property file) ● Sprung mass ● CG height ● Wheelbase ● Drive ratio ● Brake ratio ● Adams/Car uses the parameters cg_height, wheelbase, sprung_mass, and tire stiffness when calculating: ● Percent anti-dive ● Dive ● Percent anti-lift ● Lift ● Percent anti-squat ● Roll center height

12. S6-12 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Suspension Parameters (Cont.) ● Adams/Car uses the tire stiffness when calculating: ● Suspension rates ● Total roll rate

13. S6-13 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Creating Loadcases ● A loadcase is an ASCII file containing all necessary information to run a simulation. It is basically a way of scripting suspension simulations with these five analysis types: ● Parallel, opposite and single, wheel travel ● Steering ● Static load ● Roll and vertical force ● When running a loadcase, Adams/Car searches for the particular loadcase file, stored in the database. You can call many loadcases, and Adams/Car will run them one at a time. ● You can create a loadcase file by selecting Simulate  Suspension Analysis  Create Loadcase. Then, select the type of analysis you want to run, and specify the relevant data.

14. S6-14 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Warning Messages ● When you create an assembly, you will sometimes see warning messages. For example, suppose you are creating a front MacPherson suspension assembly without a steering or body subsystem. Because steering and body parts are not specified in the test rig or another subsystem, certain communicators are attached to ground or not attached to anything. The Message window displays the following:

15. S6-15 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Dynamic Analysis ● Adams/Car now provides the ability to do a dynamic analysis in addition to the other analysis. ● Use a RPC File to drive the testrig using test data or use runtime View functions. ● Issues a Sim/Dynamics command to the test rig. ● Compliance Matrix is not calculated.

16. S6-16 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Warning Messages ● The models in the shared car database contain all the communicators that could possibly be used by other systems, and in many cases, not all communicators are used. However, be sure to check out which ones aren't being connected to see if it makes sense. Here, most of them could potentially be connected to the body, or to some other subsystem you currently don't care about in your analysis. By default, if Adams/Car cannot find the matching communicator, it attaches it to ground, which, in this case, is fine. So, you usually aren't concerned about it unless you see a communicator that should be used, but isn't.

17. S6-17 ADM740, Section 6, June 2007 Copyright  2007 MSC.Software Corporation Files Produced by Analyses ● It’s important to remember that all vertical products, including Adams/Car, are simply preprocessors for Adams/Solver. This means that they simply produce the.adm file (Adams/Solver data, the model) and the.acf file (Adams/Solver commands). These files are created in the working directory (File  Select Directory). ● The output files produced include message, request, results, graphics, and output files. Adams/Car may also produce a.dcf and.dcd file, as described in Driving Machine, in Section 8. Note that Adams/Car automatically saves a results file if it detects a flexible body. Adams/PostProcessor requires the results file to plot the deformation color contours, and so on, of the flexible body. ● When you import the analysis requests file (.req) in Adams/PostProcessor, Adams/Car also produces a special file, named the name file (.nam), which contains the name associated with every request in the interface. ● You can use the.adm,.acf, and.nam files to submit an analysis outside of the Adams/Car graphical interface.