SS-T: 4210 Rotordynamic Analysis

Tutorial Level: Advanced Create modal rotordynamics analysis in SimSolid for a vertical wind turbine assembly.

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:
  • Learn to create a modal rotordynamics analysis
Model Description
The following model file is needed for this tutorial:
  • rotordynamics.ssp
Figure 1.


This file has the following specifications:
  • Material is set to Steel for all parts.
  • Regular connections - 3 mm gap and penetration tolerance.
  • SimSolid automatically creates bonded contact conditions.

Open Project

  1. Start a new SimSolid session.
  2. In the main window toolbar, click Open Project .
  3. In the Open project file dialog, choose rotordynamics.ssp
  4. Click OK.

Create Rotordynamics Analysis

  1. In the main menu toolbar, select Modal > Modal rotordynamics.
  2. In the setup dialog, select the Coriolis effect checkbox.
  3. Specify the number of modes as 9.
  4. Click OK.
    The new modal rotor dynamics analysis appears in the Project Tree.

Apply Rotational Inertia Loads

  1. In the Analysis Workbench toolbar, select Rotational inertia load.
  2. In the dialog, verify the Select a cylinder radio button is selected.
  3. In the modeling window, select the face(s) highlighted in orange in the figure below.
    Figure 2.


  4. For the Direction, enter (0,0,1) for X, Y, and Z.
  5. For Angular velocity, change the units to RPM, enter 1000 for Min, 5000 for Max, and 5 for Number of steps.
  6. Click OK.

Create Immovable Support

  1. In the Analysis Workbench, select Constraints > Immovable support.
  2. In the dialog, verify the Faces radio button is selected.
  3. In the modeling window, select the face(s) highlighted in orange in the figure below.
    Figure 3.


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

Edit Solution Settings

  1. In the Analysis branch of the Project Tree, double-click on Solution settings.
  2. In the Solution settings dialog, for Adaptation select Global+Local in the drop-down menu.
  3. Click OK.

Run Analysis

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

Review Modes

  1. In the Analysis Workbench, click Result plot > Displacement > Displacement magnitude.
    The Legend window opens and displays the contour plot. The Modes window opens and displays a list of modes.
    Figure 4.


  2. Review the modes.
    1. Select a mode from the Modes window table.
    2. In the Legend window, click Start/stop animation to view the mode animation.
      Figure 5. Mode 1


    3. Cycle between the different modes and view the mode shapes.
  3. Optional: Different angular velocities can be cycled by selecting from the Angular velocity dropdown.
    Tip: The units for angular velocity can be changed by double-clicking on Units in the Project Tree.

Plot Campbell Diagram

  1. In the Analysis Workbench, click Diagrams > Campbell diagram.
    Campbell diagram plots the natural frequencies to the rotor against its operating speeds which is used to find the critical speeds of the rotating system. Positive modes are plotted.
  2. Under Angular velocity multipliers, enter 0.001 for Multiplier.
  3. Click Add to add the line on the plot.
    The points at which the line intersects the natural frequencies line are known as the critical speeds.
    Figure 6.


  4. Optional: Plot the Damping diagram which shows how the damping is changed with respect to angular velocity.