Applying Uniform Base Motion for a Random Vibration Study

To applying uniform base motion for a random vibration study:

  1. Right-click the Load/Restraint folder and select Uniform Base Excitation.
  2. Under Type, select Displacement, Velocity, or Acceleration.
  3. Under PSD Displacement, PSD Velocity, or PSD Acceleration, do the following:
    1. For Unit , select the desired unit.
    2. Click the button for a global direction and enter a value for the Power Spectral Density of excitation.
  4. Under Variation with Frequency, select:
    • Constant to specify constant excitation for the full range of operating frequencies.
    • Curve to specify your own variation or select a library curve. Click Edit to modify the curve.
    The base motion governed by the PSD curve is applied to all selected directions. Click Graph to view the input PSD curve in all selected directions. The software uses a Log-Log interpolation method to interpolate the frequency values that fall between the frequency curve input points. The software converts the input values of the curve to Log-Log scale and interpolates linearly (in the Log-Log domain) to find the values of frequencies that fall between the curve points.
  5. Under Symbol Settings, do the following:
    1. Click Edit Color to select a color.
    2. Set Symbol Size .
  6. Click .