Random Response

Use the Random Response tool to perform a random response analysis using an existing FRF file.

  1. From the Create tools, select Create > Random Response.
    Figure 1. Random Response Dialog


  2. For Input FRF, click and browse and select a result file with FRF subcases.
    Note: Currently, the supported solvers are OptiStruct (.op2, .h3d) and Nastran (.op2).
  3. Select a subcase and a preferred frequency range.
    1. For Select Frequency Range, click Subcases.

      The Select Subcase dialog opens displaying a list of complex subcases and their frequencies.

    2. Select one subcase and a preferred frequency range.
      Figure 2. Select Subcase Dialog


    3. Click OK.
  4. For Input PSD Curve, click and browse and select a .csv file with a PSD curve.
    Note: The .csv file must have the following two-column layout with headers:
    Figure 3. CSV File Layout Example


    The first column represents the frequencies and should include the range of frequencies that are selected in the Select frequency range option (see Step 3). The second column represents the PSD load.

  5. For Output, click and browse and select the output directory and result file.
  6. For Output Request, Select result data types and components to be exported in the output file.
    All Results
    All result data types and their components will be exported in the output file.
    Select Results
    Select preferred result data types and components to be exported in the output file. By default, all results are selected.
    Figure 4. Select Results


  7. Select the preferred result calculations to be done.
    • PSD Response
    • Positive Zero Crossing
    • RMS
    • Rate of Peak
    • Spectral Moments
  8. Click and define Advanced options.
    1. Select an axis scale type from linear and logarithmic.
  9. Select Import Files After Run to import a output result file of the random response analysis in the active window if the model file is already imported.
    Note: The second option is only available for a page layout that has less than four windows.
    Figure 5. Import Results After Run Option