Sensitivity Analysis of a Bracket using NASTRAN integration node

This tutorial allows you to complete a sensitivity analysis of the Bracket:

The bracket is parametrized by the material Young's modulus E, shell thickness T, number of timesteps N, and time increment DT. The responses are the first Eigenvalue frequency and the first Eigenvalue generalized stiffness.

 

Task Description

This tutorial demonstrates how to do the following:

  • Generate an optiSLang workflow using NASTRAN integration node

  • Set up NASTRAN integration node settings

  • Define and register the parameters and the responses

 

Preparation

Before you start the tutorial, download the bd05bkt.dat file from here and add it to your project reference directory *.opr.

 

Tutorial Steps

To set up and run the tutorial, perform the following steps:

 

Creating a New Project

  1. Start optiSLang.

  2. Create a new empty project.

  3. From the Modules > Systems > Algorithms > Sampling folder, drag the Sensitivity system to the Scenery pane and let it drop.

  4. From the Modules > Process chain elements > Integrations folder, drag the NASTRAN node into the Sensitivity system and let it drop.

  5. In the Initialize Integration dialog, click the OK button to accept the defaults.

 

Setting up the NASTRAN integration node

  1. Double-click the NASTRAN integration node (or right-click the NASTRAN node and select Edit).

  2. Go to Settings tab > General subtab.

    Here you can set custom NASTRAN settings, for example, Nastran executable, additional input files, Output file format, etc.

  3. Select "OP2" as Output file format.

 

Selecting the Input File

  • On the Parametrization tab, browse the reference folder *.opr and select the bd05bkt.dat file.

 

Selecting Parameters and Response

  1. In the Inputs table, select MAT1_Id_1_E and PSHELL_Id_1_T and drag them to the Parameter pane to register them as inputs.

  2. Click the Settings tab, then click the Custom tab.

  3. Select the parameters under Custom parameters and drag them to the Parameter pane to register them as inputs.

  4. Click the Parameterization tab.

  5. On the Outputs pane, right-click EIGENVALUES__CYCLES and select "Use as internal variable".

  6. Right-click EIGENVALUES__GENERALIZED_STIFFNESS and select "Use as internal variable".

  7. Click the Variables tab.

  8. Click Add variable.

  9. Double-click the ID cell for the new variable, type FREQ_1, and press Enter.

  10. Double-click the Expression cell of row 3 (FREQ_1) and select Open Calculator from the context menu.

  11. In the Calculator, enter EIGENVALUES__CYCLES[0] and click OK.

  12. Add another new variable. Rename it STIFF_1.

  13. Update the Expression of STIFF_1 to EIGEVNVALUES_GENERALIZED_STIFFNESS[0].

  14. Drag FREQ_1 and STIFF_1 into the Responses pane to register them.

 

Setting up the Sensitivity

  1. Double-click the Sensitivity system to open the settings.

  2. On the Parameter tab, check registered parameters.

  3. On the Dynamic sampling tab, set dynamic sampling:

    1. Select Dynamic sampling.

    2. Select "Plain Monte Carlo" as the Sampling type.

    3. Set Number of samples to 10.

  4. Click Ok.

 

Saving and Running the project

  1. To save the project, click  .

  2. Right-click the Sensitivity system and select Start from here.

  3. To review the result, double-click the Sensitivity system and switch to the Result designs tab.

    To view the optiSLang Postprocessing, right-click the Sensitivity system and select Show Postprocessing.