WS4-1 WORKSHOP 4 MODAL TRANSIENT ANALYSIS NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation

WS4-2 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation

WS4-3 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation n Problem Description u Using the Modal Method, determine the transient response of the flat rectangular plate, created in Workshop 3, subject to time- varying excitation. This example structure is excited by a 1 psi pressure load over the total surface of the plate varying at 250 Hz. In addition, a 25 lb force is applied at a corner of the tip also varying at 250 Hz, but starting seconds after the pressure load begins. Both time-dependent dynamic loads are applied for the duration of seconds only. Use a modal damping of z = 0.03 for all modes. Carry out the analysis for 0.04 seconds. MODAL TRANSIENT RESPONSE

WS4-4 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation n Problem Description (cont.) u Below is a finite element representation of the flat plate. It also contains the loads and boundary constraints. MODAL TRANSIENT RESPONSE

WS4-5 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation MODAL TRANSIENT RESPONSE n Suggested Exercise Steps 1. Import the model from Workshop 1a. 2. Create a non-spatial field for the pressure load and the force load. 3. Create a time dependent load case. 4. Create the time dependent force load. 5. Create the time dependent pressure load. 6. Submit the model to MSC.Nastran for analysis. 7. Attach the.XDB results file. 8. Post Process results – create X vs Y graph of displacements.

WS4-6 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation CREATE NEW DATABASE Create a new database called ws4.db. a.File / New. b.Enter ws4 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

WS4-7 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation Step 1. File / Import Import the model from Workshop 1a. a.File / Import. b.Select MSC.Patran DB as the Source. c.Select ws1a.db. d.Click Apply. e.Click OK when the Patran Database Import Summary appears. b c a d

WS4-8 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation Step 2. Field: Create / Non Spatial / Tabular Input Create a Non Spatial field for the pressure load. a.Field: Create / Non Spatial / Tabular Input. b.Enter pressure for the Field Name. c.Select Time (t) as the Active Independent Variable. d.Click Input Data. e.Click Map Function to Table. f.Type in the function, sind(250*360*t) and values shown. g.Click Apply. h.Click OK on the table. i.Click Apply. a b c d e f g h i

WS4-9 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation Step 2. Field: Create / Non Spatial / Tabular Input (Cont.) Create a Non Spatial field for the force load. a.Enter force for the Field Name. b.Select Time (t) as the Active Independent Variable. c.Click Input Data. d.Click Map Function to Table. e.Type in the function, sind(250*360*(t )) and values shown. f.Click Apply. g.Click OK on the table. h.Click Apply. a b c d e f g h Note the required Delay has been defined by putting in a start time of and term (t-0.004)

WS4-10 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation Step 3. Load Cases: Create Create a Time Dependent load case. a.Load Cases: Create b.Enter modal_transient for the Load Case Name. c.Select Time Dependent as the Load Case Type. d.Click Assign/Prioritize Loads/ BCs. e.Click on the Displ_constraint in the Select Individual Loads/BCS field. f.Click OK. g.Click Apply. a b c e f g d

WS4-11 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation Step 4. Loads/BCs: Create / Force / Nodal Create the time dependent Force load. a.Loads/BCs: Create / Force / Nodal. b.Enter force for the New Set Name. c.Click on the Input Data button. d.Enter for Force, and select Force for the Time/Freq. Dependent Field. e.Click OK. f.Click on Select Application Region. g.Change the Geometry Filter to FEM. h.Select the bottom right corner node for the application region. i.Click Add, and click OK. j.Click Apply. a b c d e f g h i j i

WS4-12 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation Step 5. Loads/BCs: Create / Pressure / Element Uniform Create the time dependent Pressure load. a.Loads/BCs: Create / Pressure / Element Uniform. b.Enter pressure for the New Set Name. c.Change the Target Element Type to 2D. d.Click on the Input Data button. e.Enter -1 for Top Surf Pressure, and select Pressure for the Time/Freq. Dependent Field. f.Click OK. g.Click on Select Application Region. h.Select all the elements for the application region. i.Click Add, and click OK. j.Click Apply. a b c d e f g h i j i

WS4-13 NAS122, Workshop 4, 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 Transient Response. d.Change the Formulation to Modal. e.Click on Solution Parameter button. f.Enter for Wt- Mass Conversion. g.Click OK. h.Click OK. a b c d e f g h

WS4-14 NAS122, Workshop 4, 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 modal_transient from the Available Subcases field. c.Click on Subcase Parameters. d.Click on DEFINE TIME STEPS button. e.Change Delta-T to Click Enter. f.Click OK. a b c d e f

WS4-15 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation Step 6. Analysis: Analyze / Entire Model / Full Run (Cont.) Submit the model for analysis (cont.). a.Change Modal Damping to Crit. Damping (CRIT). b.Click on DEFINE MODAL DAMPING. c.Enter the values showed in the Define Damping window. d.Click OK. e.Click OK. f.Click Apply (on the Subcases form). g.Click Cancel. a b c d e

WS4-16 NAS122, Workshop 4, 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.Select modal_transient and unselect Default. c.Click OK. d.Click Apply. a b c d

WS4-17 NAS122, Workshop 4, 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 Result File. c.Select ws4.xdb. d.Click OK. e.Click Apply. a b c d e

WS4-18 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X Create a X-Y graph of displacement results. a.Results: Create / Graph / Y vs X. b.Click on SC1:MODAL_TRANSIENT. c.Select Global Variable as the Filter Method. d.Click Filter. e.Click Apply. f.Click Close. a b c d e f

WS4-19 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.) Create a X-Y graph of displacement results (cont.). a.Select Displacement, Translational for the Select Y Result field. b.Select Z Component as the Quantity. c.Click on the Target Entities icon. d.Change the Target Entity Selection to Nodes. e.Select the upper right node. Also choose the node at the center of the free edge. f.Click Apply. b a c d e f

WS4-20 NAS122, Workshop 4, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.)