1. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation WORKSHOP 5 CO-SIMULATION MODIFIERS FOR EASY 5

2. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation

3. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Overview Investigate the effect of including a EASY5-defined spring-damper element in an aircraft landing gear. Use Adams/Controls modifiers to perform a proper static analysis before the co-simulation begins and investigate the effect of interpolation order on simulation results and solution time.

4. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Investigate the Model Run a nominal simulation to investigate the model within the Adams/View environment, without Adams/Controls interaction. Start Adams/View, set the working directory to /mod5_cosimmodifiers and load the model named oleo_start.cmd. Run the simulation script named static_then_drop using the menu picks: Simulate > Scripted Controls Animate the model and note how a large force is developed in the force element “spring_force” as the drop test progresses. Modify the simulation script to inspect the commands further. Why are different constraints being activated/deactivated depending on simulation mode (static or dynamic)? __________________________________________________________ _____________________________(i)

5. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Export the Plant The force element in the model will be modified to use a spring- damper implemented in EASY5. To export the plant for this Adams model Click on the ribbon Plugin-  Controls  Plant Export - Bring up the Adams/Controls Plant Export dialog box and specify: File prefix = oleo_out Initialization cmd = ‘file/command=oleo_setup.acf’ Initial static = no Input signals = OLEO_FORCE Output signals = REL_POS, REL_VEL Target = EASY5 Other settings default Verify that the oleo_out.inf, oleo_out.adm files needed for the co- simulation get created in the working directory.

6. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Export the Plant (Cont.) Inspect the initialization command file named oleo_setup.acf by opening it in a text editor. Compare the joint IDs with the various joints in the Adams/View model. Does the sequence of activation/deactivation make sense for the static and dynamic simulation cases? (Hint: Consider the effect of joint activation/deactivation on the number of redundant constraints found in the system.) _________________________________________________________________ _________________(ii)

7. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Easy5: Setup and Co-simulation Set up the EASY5 model for co-simulation: a.Start EASY5 and load the oleo_easy5.0.ezmf model file. b.Modify the Adams block and choose Select/Configure Adams Model. Select the oleo_out model file and configure the block for Co- Simulation (Discrete) mode. c.In the Inputs tab specify: -Communication_Interval = 0.001 -ADAMS_Output_Interval = 0.005 -Both Interpolation Orders = 0 d.Verify the Inputs and Variables tabs in the block: the input/output variables REL_POS, REL_VEL and OLEO_FORCE should be defined. Run a simulation with the default EASY5 model for 1.5 seconds and a 0.001 time increment. Ensure that output files named oleo_out.msg, oleo_out.res, etc. are created in the working directory. Import these analysis files into the Adams/View model, then animate the mechanical system to verify that the EASY5 spring-damper is operating as expected.

8. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Easy5: Setup and Co-simulation (Cont.) Does the Adams_init command appear to be working as expected, running the setup script before the co-simulation? ________________________________________________________ __________________________________________________ (iii) (Hint: The animation will indicate if things are working properly. To double check the commands that are being executed, open the.msg file in a text editor and look for the initialization commands near the start of the file.)

9. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: Baseline Result Run two additional simulations to compare the effect of interpolation on simulation speed and results quality. Alter the.inf file settings in the Configure Adams Block (AD) to generate results output with unique names. To generate a baseline (no interpolation) result: 1.Edit the Configure Adams Block as shown below.

10. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: Baseline Result (Cont.) 1.Click on Done. 2.Edit the AD block and ensure that EASY5_Interpolation_Order and ADAMS_Interpolation_Order are both 0. 3.Re-run the last co-simulation. The results should be identical to the last run. 4.Save the EASY5 data file with a new name by: -In Easy5 Plotter: File -> Rename Data File… -Select the oleo_easy5.simulation.ezrpd to rename -Provide a new name of “interp0” Next, the effect of EASY5 interpolation order will be studied.

11. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: EASY5 Interpolation Run a co-simulation with the EASY5 interpolation order set to be 1. To do this: 1.Edit the Configure Adams Block as shown below.

12. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: EASY5 Interpolation (Cont.) 1.Click on Done. 2.Edit the AD block and ensure that EASY5_Interpolation_Order = 1 and ADAMS_Interpolation_Order = 0. 3.Re-run the last co-simulation. 4.Save the EASY5 data file with a new name by: 1.From Easy5 Plotter: File -> Rename Data File… 2.Select the oleo_easy5.simulation.ezrpd to rename 3.Provide a new name of “ezinterp1” Next, compare the results with/without interpolation.

13. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: EASY5 Comparison Use the EASY5 plotter to compare the results: If the EASY5 plotter is open, close it and return to the main EASY5 window. Analysis -> Open Plotter… Select the interp0.ezrpd file to plot. Open the other analysis by: - File -> Open Data Files… - Select ezinterp1.ezrpd as the data file. Use the ‘Create comparison layout file…’ button to overlay the two analyses. The result comparison should be similar to what is shown in the following figure. Use the left-mouse button to “window zoom” on the plots.

14. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: EASY5 Comparison (Cont.)

15. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: EASY5 Comparison (Cont.) Compare the simulation time as reported by Adams/Solver. To do this: Open both the interp0.msg and ezinterp1.msg files in a text editor. At the end of each file there is listed the CPU Time and Function Evaluations. Compare these for the two simulations. Consider the Questions on the following page.

16. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: EASY5 Comparison (Cont.) Questions: From the plot comparison: does interpolation order have an effect on how ‘smooth’ the inputs to the EASY5 model are? ______________________________ (iv) From the CPU Time and Function Evaluations reported in the.msg files, does the EASY5 Interpolation order have an effect on the Adams/Solver portion of the solution? ______________________________ (v)

17. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: Adams Interpolation Run the previous co-simulation with the Adams interpolation order set to be 1. To do this: Use a prefix of ezinterp1_adamsinterp1 in the.inf file. Remember to save the.inf file. Edit the AD block and set the ADAMS_Interpolation_Order to be 1. Re-run the co-simulation. Save the EASY5 data file as ezinterp1_adamsinterp1.ezrpd.

18. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: Adams Comparison To gauge the effect of the ADAMS_Interpolation_Order parameter, consider the following data: ● Create a comparison plot in EASY5 between the interp0 and ezinterp1_adamsinterp1 data files. Use the 4 th plot in EASY5 named ‘CPUSEC’ to compare overall co- simulation speed as in the following figure.

19. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Interpolation Order: Adams Question Question: Does the ADAMS_Interpolation_Order affect the overall simulation speed? ______________________________ (vi)

20. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Answers I.A temporary fixed joint (JOINT_204) is used to suspend the gear in the air in order to find static equilibrium. In dynamics this joint is not needed, but others are needed to keep the gear from toppling over. II.Yes, the sequence should make sense. The joint combination for dynamics should result in no redundant constraints in the system. The statics configuration contains three redundant constraints, but the model simulates well despite this.

21. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation Answers (Cont.) iii.The animation should show the simulation starting from the static “wheel drop” position rather than from the design configuration of the wheel assembly. This indicates that the static simulation was successful. Alternatively, open the.msg file and look near the beginning where the.acf commands from ‘oleo_setup.acf’ should be apparent. iv.The EASY5 interpolation order certainly affects the ‘smoothness’ of the Adams outputs to EASY5. Clearly EASY5 is getting a smoother output to work with. v.The CPU Time and Function Evaluations in Adams typically aren’t affected by the EASY5 Interpolation Order. vi.Typically the ADAMS_Interpolation_Order will improve the simulation speed as it provides Adams with smoother input values. Drastic changes (as in the “zero-order” sample-and-hold communication scheme) in Adams inputs generally cause problems for Adams/Solver, meaning that a smaller communication interval must be used for an interpolation order of zero.

22. ADM711, Workshop 5, January 2013 Copyright  2013 MSC.Software Corporation