WS6-1 WORKSHOP 6 MODAL FREQUENCY RESPONSE ANALYSIS NAS122, Workshop 6, August 2005 Copyright 2005 MSC.Software Corporation

WS6-2 NAS122, Workshop 6, August 2005 Copyright 2005 MSC.Software Corporation

WS6-3 NAS122, Workshop 6, August 2005 Copyright 2005 MSC.Software Corporation MODAL FREQUENCY RESPONSE n Problem Description u Using the Modal Method, determine the frequency response of the flat rectangular plate, created in Workshop 1a, excited by a 0.1 psi pressure load over the total surface of the plate and a 1.0 lb. force at a corner of the tip lagging 45. Use a modal damping of = Use a frequency step of 20 Hz between a range of 20 and 1000 Hz; in addition, specify five evenly spaced excitation frequencies between the half power points of each resonant frequency between the range of Hz.

WS6-4 NAS122, Workshop 6, August 2005 Copyright 2005 MSC.Software Corporation MODAL FREQUENCY RESPONSE n Problem Description (cont.) u Below is a finite element representation of the flat plate. It also contains the loads and boundary constraints psi. over the total surface

WS6-5 NAS122, Workshop 6, August 2005 Copyright 2005 MSC.Software Corporation MODAL FREQUENCY 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.

WS6-6 NAS122, Workshop 6, August 2005 Copyright 2005 MSC.Software Corporation CREATE NEW DATABASE Create a new database called ws6.db. a.File / New. b.Enter ws6 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

WS6-7 NAS122, Workshop 6, 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. a b c d

WS6-8 NAS122, Workshop 6, 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 Frequency (f) as the Active Independent Variable. d.Click Input Data. e.Enter the values showed in the table. f.Click OK. g.Click Apply. a b c d e f g

WS6-9 NAS122, Workshop 6, 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.Field: Create / Non Spatial / Tabular Input. b.Enter force for the Field Name. c.Select Complex as the Scalar Field Type. d.Click Input Data. e.Change the Complex Data Format to Magnitude-Phase (degrees). f.Enter the values showed in the table. g.Click OK. h.Click Apply. a b c d e f h g

WS6-10 NAS122, Workshop 6, 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_freq_response 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. b c d e f g a

WS6-11 NAS122, Workshop 6, August 2005 Copyright 2005 MSC.Software Corporation Step 4. Loads/BCs: Create / Force / Element Uniform 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 node on the bottom right corner. i.Click Add, and click OK. j.Click Apply. a b c d e f g h j i i

WS6-12 NAS122, Workshop 6, 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 -0.1 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

WS6-13 NAS122, Workshop 6, 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 Frequency Response. d.Change the Formulation to Modal. e.Click on Solution Parameter button. f.Select Coupled for Mass Calculation. g.Enter for Wt-Mass Conversion. h.Click OK. i.Click OK. a b c d e f h i g

WS6-14 NAS122, Workshop 6, 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_freq_response from the Available Subcases field. c.Click on Subcase Parameters. d.Click on DEFINE FREQUEYNCIES button. e.Use the values in the table. f.Click OK. a b c d e f

WS6-15 NAS122, Workshop 6, 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 Subcase form). g.Click Cancel. a b c d e

WS6-16 NAS122, Workshop 6, 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_freq_response and unselect Default. c.Click OK. d.Click Apply. a b c d

WS6-17 NAS122, Workshop 6, 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 ws6.xdb. d.Click OK. e.Click Apply. a b c e d

WS6-18 NAS122, Workshop 6, 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_FREQ_ RESPONSE. c.Select Global Variable as the Filter Method. d.Click Filter. e.Click Apply. f.Click Close. a b c d e f

WS6-19 NAS122, Workshop 6, 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 node where force is applied. f.Click Apply. b a c d e f

WS6-20 NAS122, Workshop 6, 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.Click on Display Attribute. b.Change Y Axis Scale from Linear to Log. c.Click on Plot Option. d.Change the Complex No. as to Magnitude. e.Click Apply. b a c d e

WS6-21 NAS122, Workshop 6, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.) Displacement Magnitude vs. Frequency Plot

WS6-22 NAS122, Workshop 6, August 2005 Copyright 2005 MSC.Software Corporation Step 8. Results: Create / Graph / Y vs X (Cont.) Create a X-Y graph of phase results. a.Change Complex No. as from Magnitude to Phase. b.Change Y Axis Scale from Log to Linear. c.Click Apply. a b a