WS14a-1 WORKSHOP 14A MODAL ANALYSIS OF A TOWER NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation

WS14a-2 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation

WS14a-3 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation n Problem Description u In this workshop, perform a normal modes analysis of a tower structure model, and observe the resulting eigenvalues and eigenvectors.

WS14a-4 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation n Suggested Exercise Steps 1. Import the finite element model of the tower from an MSC.Nastran input file named enf111.bdf. 2. Use MSC.Patrans mass properties tool to check the total mass of the model. 3. Submit the model to MSC.Nastran for a normal modes analysis. 4. Open the.f06 file and observe the weight generator table. 5. Attach the.XDB result file after the analysis is completed. 6. Use the Quick Plot feature in the Results menu to visualize the eigenvectors of the model.

WS14a-5 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation CREATE NEW DATABASE Create a new database called tower.db. a.File / New. b.Enter tower 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

WS14a-6 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation Step 1. File / Import Import the model from a MSC.Nastran Input File called enf111.bdf. a.File / Import. b.Select MSC.Nastran Input as the Source. c.Select enf111. bdf and click Apply. d.Click OK when the Nastran Input File Import Summary appears. b c a c d

WS14a-7 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation Step 1. File / Import (Cont.)

WS14a-8 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation Step 2. Tools / Mass Properties: Show / 3D Check the total mass of the tower. a.Tools / Mass Properties. b.Show / 3D. c.Click on Define Region. d.Select default_group. e.Click OK. f.Click Apply. b c d a e f

WS14a-9 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation Step 3. Analysis: Analyze / Entire Model / Full Run Submit the model for analysis. a.Analysis: Analyze / Entire Model / Full Run. b.Enter tower normal modes as the Job Name. c.Click on Solution Type. d.Select NORMAL MODES. e.Click on Solution Parameters button. f.Make sure the value for Wt-Mass Conversion is 1.0. g.Enter 1 for the Node i.d. for Wt. Gener. h.Click OK. i.Click OK. a c d e i b f g h

WS14a-10 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation Step 3. Analysis: Analyze / Entire Model / Full Run (Cont.) Submit the model for analysis (cont.). a.Click on Subcase Select… b.Select UNTITLED.SC1 in the Subcases For Solution Sequence and Unselect the Default load case. c.Click OK. d.Click Apply. b a c d

WS14a-11 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation Step 4: Study Weight Generator Table in the.f06 file

WS14a-12 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation Step 5. 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 tower_normal_modes.xdb. d.Click OK. e.Click Apply. a b c d e

WS14a-13 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation Step 6. Results: Create / Quick Plot Create a Deformation and Fringe plot of the normal modes. a.Results: Create / Quick Plot. b.Select the Mode 1. c.Select Eigenvector, Translational in both Result boxes. d.Click Apply. e.Repeat the same procedures for the remaining 9 normal modes. a b c d c

WS14a-14 NAS122, Workshop 14a, August 2005 Copyright 2005 MSC.Software Corporation Summary Summary of Frequencies and Modes for project _______________ ModeFreq (Hz) Description