WS13b-1 WORKSHOP 13B MODAL ANALYSIS OF A CAR CHASSIS WITHOUT RIGID BODY MODES NAS122, Workshop 13b, August 2005 Copyright 2005 MSC.Software Corporation

WS13b-2 NAS122, Workshop 13b, August 2005 Copyright 2005 MSC.Software Corporation

WS13b-3 NAS122, Workshop 13b, August 2005 Copyright 2005 MSC.Software Corporation MODAL ANALYSIS OF A CAR CHASSIS WITHOUT RIGID BODY MODES n Problem Description u The purpose of this workshop is to perform a Normal Modes analysis of a Body-in-White model of a car.

WS13b-4 NAS122, Workshop 13b, August 2005 Copyright 2005 MSC.Software Corporation MODAL ANALYSIS OF A CAR CHASSIS WITHOUT RIGID BODY MODES n Suggested Exercise Steps 1. Open the database called car.db. 2. Submit the model to Nastran for a Normal Modes analysis. 3. Attach the XDB result file after the analysis is completed. 4. Use the Quick Plot feature in the Result Menu to visualize the Eigenvector of the model.

WS13b-5 NAS122, Workshop 13b, August 2005 Copyright 2005 MSC.Software Corporation Step 1. File / Open Open the database called car.db. a.File / Open. b.Select car.db. c.Click OK. a b c

WS13b-6 NAS122, Workshop 13b, August 2005 Copyright 2005 MSC.Software Corporation Step 2. Analysis: Analyze / Entire Model / Full Run Submit the model for analysis. a.Analysis: Analyze / Entire Model / Full Run. b.Enter car_nm_no_rigid as the Job Name. c.Click on Solution Type. d.Select NORMAL MODES. e.Click OK. a c d e b

WS13b-7 NAS122, Workshop 13b, August 2005 Copyright 2005 MSC.Software Corporation Step 2. Analysis: Analyze / Entire Model / Full Run (Cont.) Submit the model for analysis (cont.). a.Click on Subcases. b.Select Default. c.Click Subcase Parameters. d.Enter 0.01 for the Lower Frequency Range of Interest. e.Click OK. f.Click Apply. g.Click Yes when the Warning Message appears. h.Click Cancel to exit the Subcases form. i.Click Apply. a c d f e b g h i

WS13b-8 NAS122, Workshop 13b, August 2005 Copyright 2005 MSC.Software Corporation Step 3. 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_nm_no_rigid.xdb. d.Click OK. e.Click Apply. a b c d e

WS13b-9 NAS122, Workshop 13b, August 2005 Copyright 2005 MSC.Software Corporation Step 4. Results: Create / Quick Plot Create a Deformation and Fringe plot of the normal modes. a.Results: Create / Quick Plot. b.Select the A2:Mode 1. c.Select Eigenvector, Translational in both Result boxes. d.Click Apply. a b c d c

WS13b-10 NAS122, Workshop 13b, August 2005 Copyright 2005 MSC.Software Corporation Summary Summary of Frequencies and Modes for project _______________ ModeFreq (Hz) Description