Problem: A submarine pressure hull is modeled by plate and bar elements. Using MSC SimXpert, check the pressure hull for buckling at an operating depth of 1000 ft which is equivalent to an external pressure of 445 psi.
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1) Click Structures.



1) Check in the lower right-hand corner for the current system of units.

2) If the current system of units is not English units (in, lb, s), click on the box to bring up the User Options form.

3) Click Standard Units.

4) Scroll down and select the line with units in, lb, s,…

5) Click OK and OK.

6) Pull down Tools > Options.

7) Expand Input/Output.

8) Highlight Nastran.Structures.

9) Uncheck Reduce Parts.

10) Click OK.





1) Pull down File > Import > Nastran.

2) Navigate to and select pressure_hull.bdf.

3)Click Open.

4) Pull down FE WireFrame on the Render toolbar.







1) Uncheck the check boxes for Parts SHELL_3…, BARS_4…, and BARS_5…. The model will appear as shown.

2) Under the LBCs tab, click Fixed in the Constraints group.

3) Click in the Entities text box.

4) Select the node at the tip of the shell as shown and click OK.





1) Click Pressure in the Pressure group.

2) Click in the Entities text box and select Select All on the Pick Filter.

3) Enter 445 for Pressure value.

4) Click OK.



1) Right-click pressure_hull.bdf and select Create new Nastran job.

2) Enter submarine for Job Name.

3) Select Linear Buckling Analysis (SOL 105) for Solution Type.

4 If desired, click the folder icon for Solver Input File and select a location to save analysis files.

5) Click OK.

6) Double-click Loadcase Control under Eigenvalue Extraction.

7) Highlight Eigenmode Extraction.

8) Select Lanczos for Method.

9) Enter 5 for Number of Desired Roots.

10) Select Maximum for Result Normalization Method.

11) Click Apply and Close.





1) Right-click submarine and select Run.

2) Select File > Attach Results. Click OK.

3) Locate submarine.bdf under File Path and click OK. .







1) Right-click any Part and select Show All.

2) Hide the display of Boundary Condition Symbols.

3) Under the Results tab, click Deformation.

4) Highlight Mode 1 for the Result Case.

5) THighlight Eigenvectors, Translational for Result type.

6) Click the Deformation tab.

7) Select Wireframe for the Deformed Shape Render style.

8) Uncheck Show undeformed box.

9) Click Update.











1) Click the Plot Data tab.

2) Highlight Mode 2 for the Result Case.

3) Click the Deformation tab.

4)Select Shaded for Render style.

5) Select the color Green for Edge color.

6) Click Update.

7) Note the Buckling Load Factor.







1) Click the Plot Data tab.

2) Highlight Mode 3 for the Result Case.

3) Click the Deformation tab.

4) Select Wireframe for Render style.

5) Select the color White for Edge color.

6) Check Show undeformed.

7) Select Wireframe for Undeformed shape Render style.

8) Select the color Red for Undeformed shape Edge color.

9) Click Update . Note the Buckling Load Factor .







1) Click the Plot Data tab.

2) Highlight Mode 4 for the Result Case.

3) Click Update. Note the Buckling Load Factor.





1) Highlight Mode 5 for the Result Case.

2) Click the Deformation tab.

3) Select Shaded for Render style.

4) Select the color Green for Edge color.

5) Select the color Green for Edge color.

6) Click Update. Note the Buckling Load Factor.