WS1a-1 WORKSHOP 1A NORMAL MODES ANALYSIS NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation

WS1a-2 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation

WS1a-3 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation NORMAL MODES ANALYSIS n Problem Description u For this problem, we use the Lanczos method to find the first ten natural frequencies and mode shapes of a flat rectangular plate. Below is a finite element representation of the rectangular plate. It also contains the geometric dimensions and the loads and boundary constraints. Table 1 contains the necessary parameters to construct the input file (see next page).

WS1a-4 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation NORMAL MODES ANALYSIS n Problem Description (cont.) u Table1

WS1a-5 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation NORMAL MODES ANALYSIS n Suggested Exercise Steps 1. Create a geometry surface using the given dimensions. 2. Mesh the surface with Quad elements using Global Edge Length of Assign the boundary conditions to the model. 4. Create the appropriate material properties and call it mat_1. 5. Assign the appropriate element properties to the model and call it prop_1. 6. Submit the model to MSC.Nastran for analysis. 7. Attach the.XDB results file. 8. Post Process results – create a quick plot for each of the 10 mode shapes.

WS1a-6 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation CREATE NEW DATABASE Create a new database called ws1.db. a.File / New. b.Enter ws1a 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

WS1a-7 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation Step 1. Geometry: Create / Surface / XYZ Create a 5 x 2 surface. a.Geometry: Create / Surface / XYZ. b.Enter as the Vector Coordinates List. c.Turn off Auto Execute. d.Click Apply. a d c b

WS1a-8 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation Step 2. Elements: Create / Mesh / Surface Create the finite elements on the surface. a.Elements: Create / Mesh / Surface. b.Select Quad for Elem Shape and IsoMesh for Mesher. c.Screen pick Surface 1 for the Surface List. d.Uncheck the Automatic Calculation option. e.Change the Global Edge Length value to 0.5. f.Click Apply. a b c d e f

WS1a-9 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation Step 3. Loads/BCs: Create / Displacement / Nodal Assign the boundary constraints to the finite element model. a.Loads/BCs: Create / Displacement / Nodal b.Enter constraint for the New Set Name. c.Click Input Data. d.Input the value for the Translation and for the Rotation e.Click OK. f.Click on Select Application Region. g.Change the Geometry Filter to FEM. h.Select all the nodes on the left edge of the plate. i.Click Add and OK. j.Click Apply. a b c d e f g h i i j

WS1a-10 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation Step 4. Materials: Create / Isotropic / Manual Input Create the material properties. a.Materials: Create / Isotropic / Manual Input. b.Enter mat_1 for the Material Name. c.Click Input Properties. d.Enter 3e7 for the Elastic Modulus and 0.3 for Poisson Ratio. e.Enter for the Density. f.Click OK. g.Click Apply. a b c d e f g

WS1a-11 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation Step 5. Properties: Create / 2D / Shell Assign element properties to the model. a.Properties: Create / 2D / Shell. b.Enter prop_1 for the Material Name. c.Click Input Properties. d.Click in the Material Name icon, and select mat_1 from the Select Material box. e.Enter 0.1 for the Thickness. f.Click OK. g.Select Surface 1 in the Select Members box. h.Click Add and click Apply. a b c e f g h h d

WS1a-12 NAS122, Workshop 1a, 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.Click on Solution Type. c.Select Normal Modes. d.Click on Solution Parameter. e.Enter for Wt- Mass Conversion. f.Click OK. g.Click OK. a b c d e f g

WS1a-13 NAS122, Workshop 1a, 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 Default in Available Subcases c.Click on Subcase Parameters. d.Select Lanczos Extraction Method. e.Enter 10 as the Number of Desired Roots. f.Select Mass for Normalization Method. g.Click OK. h.Click Apply. i.Click Cancel. j.Click Apply. a i c d e f g h j b

WS1a-14 NAS122, Workshop 1a, 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 ws1a.xdb. d.Click OK. e.Click Apply. a b c d e

WS1a-15 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Quick Plot Create a Quick Plot of the first mode shape. a.Results: Create / Quick Plot. b.Click on A1:Mode1. c.Select Eigenvector, Translational in both Fringe and Deformation result boxes. d.Click Apply. a b c d c

WS1a-16 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Quick Plot

WS1a-17 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation Summary Summary of Frequencies and Modes for project _______________ ModeFreq (Hz) Description

WS1a-18 NAS122, Workshop 1a, August 2005 Copyright 2005 MSC.Software Corporation