1. WS2-1 ADM703, Workshop 2, August 2005 Copyright  2005 MSC.Software Corporation WORKSHOP 2 SPRING-DAMPER SYSTEM

2. WS2-2 ADM703, Workshop 2, August 2005 Copyright  2005 MSC.Software Corporation

3. WS2-3 ADM703, Workshop 2, August 2005 Copyright  2005 MSC.Software Corporation WORKSHOP 2 – SPRING-DAMPER SYSTEM n Problem Statement u Create differential equations to represent the acceleration and velocity of a simple spring-damper system. Compare with results from an MSC.ADAMS model. n Model Description u A simple mass constrained using a translation joint. A spring damper acts on the remaining translational degree of freedom.

4. WS2-4 ADM703, Workshop 2, August 2005 Copyright  2005 MSC.Software Corporation WORKSHOP 2 – SPRING-DAMPER SYSTEM (CONT.) n Creating differential equations u Here, you create differential equations to model the mass motion. n To create the differential equation: 1. Import the model install_dir/springdamper/smd.cmd, where install_dir is the directory where the training files are installed. 2. Modify the block part and spring damper, and note the block mass, spring stiffness coefficient, and spring damping coefficient. Store these values in ADAMS/View variables (that is, design variables) called m, k, and c, respectively.

5. WS2-5 ADM703, Workshop 2, August 2005 Copyright  2005 MSC.Software Corporation WORKSHOP 2 – SPRING-DAMPER SYSTEM (CONT.) n To create the differential equation (Cont.) 3. Create a dummy differential equation called Dif_eq_dummy.

6. WS2-6 ADM703, Workshop 2, August 2005 Copyright  2005 MSC.Software Corporation WORKSHOP 2 – SPRING-DAMPER SYSTEM (CONT.) n To create the differential equation (Cont.) 4. Create an explicit differential equation called Dif_eq_vel, by entering the following: Function = DIF (.smd.Dif_eq_dummy) Tip: Use the ADAMS/View Function Builder to build this function. The DIF and DIF1 functions are under the Data Element category.

7. WS2-7 ADM703, Workshop 2, August 2005 Copyright  2005 MSC.Software Corporation n To create the differential equation (Cont.) 5. Create an explicit differential equation called Dif_eq_accel, by entering the following: Function = 9.81-(c/m)*DIF1(.smd.Dif_eq_vel)-(k/m)*DIF(.smd.Dif_eq_vel) Note: 9.81 represents gravity. Make adjustments for units, if necessary. 6. Modify Dif_eq_vel as follows: Function = DIF (.smd. Dif_eq_accel) 7. From the Edit menu, select Delete, and then delete Dif_eq_dummy. 8. Create an ADAMS/Solver variable (that is, state variable) called box_velocity to track the box velocity by entering the following: Function = VR(cm) Note: VR is a “velocity along line-of-sight” solver function. WORKSHOP 2 – SPRING-DAMPER SYSTEM (CONT.)

8. WS2-8 ADM703, Workshop 2, August 2005 Copyright  2005 MSC.Software Corporation n Simulating and Postprocessing u Next, you run a simulation and post process the results. n To run the simulation and post process the results: 1. Run a dynamic simulation for 2.0 seconds with 100 steps. 2. In ADAMS/Postprocessor, change Source to Results Sets and compare the values of the differential equations to the values of the block velocity and displacement. Do they correlate? If not, investigate your differential equation. WORKSHOP 2 – SPRING-DAMPER SYSTEM (CONT.)

9. WS2-9 ADM703, Workshop 2, August 2005 Copyright  2005 MSC.Software Corporation WORKSHOP 2 – SPRING-DAMPER SYSTEM (CONT.)

10. WS2-10 ADM703, Workshop 2, August 2005 Copyright  2005 MSC.Software Corporation WORKSHOP 2 – SPRING-DAMPER SYSTEM (CONT.) n To run the simulation and post process the results (Cont.): u Tip: Another way to confirm differential equations is to export your.adm file. Select File  Export and change the file type to ADAMS/Solver Data Set to write an.adm file to your working directory. The differential equations should look like the figure shown below. You can also refer to the file,../springdamp_completed/smd.adm in the training materials provided.