WS17-1 WORKSHOP 17 DIRECT TRANSIENT ANALYSIS OF A CAR CHASSIS NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation

WS17-2 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation

WS17-3 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation DIRECT TRANSIENT ANALYSIS OF A CAR CHASSIS n Problem Description u In this particular problem, the user is asked to perform a Direct Transient Analysis on a car model to simulate the effect of going over a bump on the road. A time-dependent enforced displacement will be used to simulate the bump and is applied to the right front suspension of the car. In the end, the user will examine the bump effect at three locations on the car by plotting a displacement vs. time plot.

WS17-4 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation DIRECT TRANSIENT ANALYSIS OF A CAR CHASSIS n Problem Description (cont.) Time Dependent Enforce Displacement Pin Constraint to simulate contact with road

WS17-5 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation DIRECT TRANSIENT ANALYSIS OF A CAR CHASSIS n Suggested Exercise Steps 1. Import the car geometry from a Nastran Input File. 2. Create a field that represents the displacement over time when a car encounter a bump. 3. Verify the field by using Field: Show feature. 4. Create a time dependent load case called Bump. 5. Create a constraint on the rear suspension and apply the field from step 2 to the left front suspension. 6. Submit the model to Nastran for analysis. 7. Attach the XDB results file. 8. Create a XY Graph of the results to view the displacement over time at various locations on the car.

WS17-6 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation CREATE NEW DATABASE Create a new database called car_direct_transient.db. a.File / New. b.Enter car_direct_transient as the file name. c.Click OK. d.Choose Default Tolerance. e.Select MSC.Nastran as the Analysis Code. f.Select Structural as the Analysis Type. g.Click OK. a b c d e f g

WS17-7 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 1. File / Import Import the model from a Nastran Input File. a.File / Import. b.Select MSC.Nastran Input as the Source. c.Select car_w_suspension.bdf and click Apply. d.Click OK when the Nastran Input File Import Summary appears. b c a c d

WS17-8 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 2. Fields: Create / Non Spatial / Tabular Input Create a time dependent non-spatial field. a.Fields: Create / Non Spatial / Tabular Input b.Enter bump for the Field Name. c.Select Time (t) as the Active Independent Variables. d.Click on Input Data button. e.Click on Map Function to Table. f.Enter the function sind(10*360*t). g.Enter the Start Time of 0.1, End Time of 0.15, and 20 for the Number of Points. h.Click Apply. a b c e g d f h

WS17-9 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 2. Fields: Create / Non Spatial / Tabular Input (Cont.) Create a time dependent non-spatial field (cont.). a.Change the values of the first two inputs to 0. b.Enter 2 additional time steps at the end of the table as shown in the figure. c.Click OK. d.Click Apply. a b c d

WS17-10 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 3. Fields: Show Use the Show feature to verify the field created in the previous step. a.Fields: Show b.Select bump for the Select Field To Show. c.Click on Specify Range button. d.Check the Use Existing Points option. e.Click OK. f.Click Apply. g.Click on Unpost Current XYWindow after verifying the field. a b c e d f g

WS17-11 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 4. Load Cases: Create Create a Time Dependent load case called bump. a.Load Cases: Create. b.Enter bump for the Load Case Name. c.Change the Load Case Type to Time Dependent. d.Click Apply. a b c d

WS17-12 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 5. Loads/BCs: Create / Displacement / Nodal Apply a pin constraint to the rear suspension. a.Loads/BCs: Create / Displacement / Nodal. b.Enter pin_rear_suspension for the New Set Name. c.Click on Input Data button. d.Enter for the Translations. e.Click OK. f.Click Select Application Region. g.Change the Geometry Filter to FEM. h.Select the bottom of the two rear suspension structures. i.Click Add and Click OK. j.Click Apply. a b c d e h i i j f g

WS17-13 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 5. Loads/BCs: Create / Displacement / Nodal (Cont.) Apply an enforced displacement to one of the front suspension that incorporate the bump field. a.Enter bump for the New Set Name. b.Click on Input Data button. c.Enter for the Translations and select bump from the Time/Freq. Dependent Fields. d.Click OK. e.Click Select Application Region. f.Select the bottom of the left front suspension. g.Click Add and Click OK. h.Click Apply. a b c d f g g h e

WS17-14 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 5. Loads/BCs: Create / Displacement / Nodal (Cont.)

WS17-15 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 6. Analysis: Analyze / Entire Model / Full Run Submit the model for analysis. a.Analysis: Analyze / Entire Model / Full Run. b.Enter car_bump for the Job Name. c.Click on Solution Type. d.Select TRANSIENT RESPONSE. e.Change the Formulation to Direct. f.Click on Solution Parameters. g.Enter 0.1 for the Struct. Damping Coefficient. h.Enter 46.0 for W3, Damping Factor and for W4, Damping Factor i.Click OK on the two sub- forms to return to the main analysis menu. a b c d e f g i i h

WS17-16 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 6. Analysis: Analyze / Entire Model / Full Run (Cont.) Submit the model for analysis (cont.). a.Click on Subcases. b.Select bump from the Available Subcases box. c.Click on Subcase Parameters. d.Click on DEFINE TIME STEPS. e.Enter the value and setting as shown in the table. f.Click OK twice. a b c d f e f

WS17-17 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 6. Analysis: Analyze / Entire Model / Full Run (Cont.) Submit the model for analysis (cont.). a.Click on Output Request. b.Select Accelerations from the Select Result Type box. c.Click OK. d.Click Apply. e.Click Cancel. a b c d e

WS17-18 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 6. Analysis: Analyze / Entire Model / Full Run (Cont.) Submit the model for analysis (cont.). a.Click on Subcase Select. b.Click on Default in the Subcase Selected box to unselect the Default subcase. c.Click on bump in the Subcases For Solution Sequence box. d.Click OK. e.Click Apply to submit the model to Nastran for analysis. a c d e b

WS17-19 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 7. Analysis: Access Results / Attach XDB / Result Entities Attach the XDB result file. a.Analysis: Access Results / Attach XDB / Result Entities. b.Click on Select Results File. c.Select car_bump.xdb. d.Click OK. e.Click Apply. a b d e c

WS17-20 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X Create a graph of Z-displacement versus frequency. a.Results: Create / Graph / Y vs X. b.Click on SC1 result case. c.Click on Filter. d.Click Apply. e.Click on Close. a b c d e

WS17-21 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.) Create a graph of Z-displacement versus frequency (cont.). a.Select Displacement, Translational. b.Change the Quantity from Magnitude to Z Component. c.Click on Target Entities Icon. d.Type in the nodes shown in the figure on the next page. e.Click Apply. a c d e b

WS17-22 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.) Node 8640 Node 7858 Node 8798

WS17-23 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.)

WS17-24 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.) Create a graph of X-displacement versus frequency. a.Click on Select Results. b.Select Displacement, Translational. c.Change the Quantity from Z Component to X Component. d.Click Apply. a b c d

WS17-25 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.)

WS17-26 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.) Create a graph of Y-displacement versus frequency. a.Change the Quantity from X Component to Y Component. b.Click Apply. a b

WS17-27 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.)

WS17-28 NAS122, Workshop 17, August 2005 Copyright 2005 MSC.Software Corporation