SS-T: 4070 Random Response Analysis

Create random response analysis in SimSolid.

Purpose
SimSolid performs meshless structural analysis that works on full featured parts and assemblies, is tolerant of geometric imperfections, and runs in seconds to minutes. In this tutorial, you will do the following:
  • Create dynamic random analysis for a walkway assembly with base excitation load.
Model Description
The following files are needed for this tutorial:
  • Random.ssp
  • PSD_Function.csv


Figure 1.
The project file has the following specifications:
  • Material is set to Steel for all parts.
  • Regular connections with 3mm gap and penetration tolerance.

Open Project

  1. Start a new SimSolid session.
  2. Click the (Open Project) icon.


    Figure 2.
  3. In the Open project file dialog, choose Random.ssp
  4. Click OK.

Create Modal Analysis

  1. On the main window toolbar, click the (Modal analysis) icon.


    Figure 3.
  2. In the popup Number of modes window, specify the number of modes as 9.
  3. Click OK.
    The new modal analysis appears in the Project Tree.

Create Immovable Support

  1. In the Analysis Workbench, click (Immovable support).


    Figure 4.
  2. In the dialog, verify the Faces radio button is selected.
  3. In the modeling window, select the two faces shown in Figure 5.


    Figure 5.
  4. Click OK.
    The new constraint, Immovable 1, appears in the Project Tree. A visual representation of the constraint is shown on the model.

Run Analysis

  1. In the Project Tree, open the Analysis Workbench.
  2. Click (Solve).

Review Results

  1. In the Project Tree, Select the Modal 1 subcase.
  2. On the Analysis Workbench, select > Displacement Magnitude.
    The Legend window opens and displays the contour plot. The Frequency (Hz) window opens and lists the modes.
    Figure 6.

Create Random Response Analysis

  1. On the main window toolbar, select > Random response.
    The Dynamic random response setup dialog opens and automatically links to the Modal analysis results.


    Figure 7.
  2. For Frequency span, set the Lower limit to 0 and the Upper limit to 28.1553.
  3. Select the Modal damping tab.
  4. Set the Default damping ratio to 0.03.
  5. Click OK.
  6. Accept warning message.

Create PSD Functions

PSD functions are referenced by dynamic loads.

  1. In the Project Tree, click on the Assembly branch to open the Assembly workbench.
  2. On the workbench toolbar, click the (Power Spectral Density function) icon.
  3. In the dialog, click the Import CSV button.


    Figure 8.
  4. In the File explorer, browse to the PSD_Function.csv file and click Open.
    The function is plotted in the XY graph in the dialog.


    Figure 9.

Define Loads

  1. On the Assembly workbench toolbar, click the (Base excitation) icon.
  2. In the dialog, ensure Excitation type is set to Acceleration.
  3. Ensure Units are set to [m/sec^2].
  4. For Amplitude, enter 10.
  5. For direction, enter 1 for X, Y, and Z.


    Figure 10.
  6. Click OK.

Run Analysis

  1. In the Project Tree, open the Analysis Workbench.
  2. Click (Solve).

Review Results

  1. In the Project Tree, Select the Dynamic random 1 subcase.
  2. On the Analysis Workbench, select > Displacement Magnitude.
    The Legend window opens and displays the contour plot. The Dynamics random response window opens. You can use the slider to animate frequencies.


    Figure 11.

Plot Response Curve

  1. On the workbench toolbar, click the (Pick info) icon.
  2. Verify the Pick point/face radio button is selected.
  3. In the modeling window, select a point on the model as shown in Figure 12.


    Figure 12.
    The response for the point is plotted in the XY graph in the dialog. You can use the scroll wheel to zoom in, the left mouse button to pan, or the Refit button to reset the graph.


    Figure 13.
  4. Obtain Partial Response.
    1. In the dialog, pick a point on the curve to show the Modes contributions into response table.


      Figure 14.
    2. In the table, select a row to choose what mode to include in the partial response.
      Tip: You can sort the table by clicking on the column headers.
    3. Click Evaluate response.
    The plot in the dialog updates to show the partial response.