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Modal analysis example
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WORKSHOP 10A
MODAL ANALYSIS OF A CIRCUIT BOARDBOARD
WS10a-1NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
WS10a-2NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
MODAL ANALYSIS OF A CIRCUIT BOARD
Problem DescriptionThe purpose of this exercise is to prepare a Printed Circuit Board (PCB) for a Frequency Response Analysis. The user will import a MSC.Nastran Bulk Data file that contains the finite element definition of the PCB, assign the appropriate boundary conditions and submit the analysis for a Normal Modes Analysis.and submit the analysis for a Normal Modes Analysis.After the analysis is completed, user will use MSC.Patran to post-process the results. The main objective is to observe the natural frequencies of the PCB because they will be important at verifying the results from a Frequency Response Analysis.
WS10a-3NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
MODAL ANALYSIS OF A CIRCUIT BOARD
Problem Description (cont.)The following is a finite element representation of the Printed Circuit Board (PCB)
WS10a-4NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
MODAL ANALYSIS OF A CIRCUIT BOARD
Suggested Exercise Steps1. Import the model from a Nastran Input File.2. Create the boundary conditions.3. Submit the model to MSC.Nastran for analysis.4. Attach the .XDB results file.5. Post Process results – create a Deformation and Fringe Plot of the
eigenvectors of the normal modes.
WS10a-5NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
CREATE NEW DATABASE
a
d
Create a new database called ws10a.db.
a. File / New.
d
a. File / New.b. Enter ws10a as the file name.c. Click OK.d. Choose Default Tolerance.e. Select MSC.Nastran as the
A l i C d
b c
e
f
gAnalysis Code.
f. Select Structural as the Analysis Type.
g. Click OK.
WS10a-6NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
Step 1. File / Import
a
b
a
Import the model from a Nastran Input file.
a. File / Import.b. Select MSC.Nastran Input as cthe Source.c. Select pcb.bdf and click
Apply.d. Click OK when the Nastran
Input File Import Summary
c
p p yappears.
WS10a-7NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
Step 2. Loads/BCs: Create / Displacement / Nodal
Create the boundary condition. a. Loads/BCs: Create /
/Displacement / Nodal.b. Enter constraint for the
New Set Name.c. Click on the Input Data
button.
a
d
d. Enter <0,0,0> for Translations.
e. Click OK.f. Click on Select
Application Region.
g
pp gg. Change the Geometry
Filter to FEM.h. Select the 4 corner
nodes showed on the next page.
b
hi
p gi. Click Add, and click OK.j. Click Apply.
c
e
fi
WS10a-8NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
fj
i
Step 2. Loads/BCs: Create / Displacement / Nodal (Cont.)
WS10a-9NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
Step 3. Analysis: Analyze / Entire Model / Full Run
Submit the model for analysis. aa. Analysis: Analyze / Entire
Model / Full Run.b. Enter ws10a for the Job
Name.c. Click on Solution Type. yd. Select NORMAL MODES. e. Click on Solution
Parameter button.f. Enter 0.00259 for Wt-Mass
Conversion.
d
Conversion.g. Click OK.h. Click OK.i. Click Apply.
bf
ce
WS10a-10NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
hg i
Step 4. Analysis: Access Results / Attach XDB / Result Entities
Attach the XDB result file.aa. Analysis: Access
Results / Attach XDB / Result Entities.
b. Click on Select Result File.
a
c
c. Select ws10a.xdb.d. Click OK.e. Click Apply.
d
b
WS10a-11NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
e
Step 5. Results: Create / Quick Plot
Create a Deformation and F i l f h l
ba
Fringe plot of the normal modes.
a. Change the view to Iso View 3.
b. Results: Create /
c
Quick Plot.c. Select the Mode 1.d. Select Eigenvector,
Translational in both Result boxes.
de. Click Apply.f. Repeat the same
procedures for the remaining 9 normal modes.
d
d
WS10a-12NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
e
Summary
Summary of Frequencies and Modes for project _______________
Mode Freq (Hz)
Description
WS10a-13NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation
WS10a-14NAS122, Workshop 10a, January 2004Copyright© 2004 MSC.Software Corporation