Random Vibration

The Random Vibration Options dialog box sets the options for the random vibration study.

Units Sets the unit of frequency. The choices are cycles/sec (Hz) and radians/sec.
Lower limit Sets the lower limit of the exciting frequency to be considered in the solution (default is 1.0E-11).
Upper limit Sets the upper limit of the exciting frequency to be considered in the solution (default is 1.0E+5).
Number of frequency points Sets the number of the solution's frequency points to be selected between any two adjacent natural frequencies. The limit on the total number of solution steps is 10000.
Correlation Sets the correlation between loads (including base excitation). If the excitations are correlated, the cross-spectral density terms are included in the analysis.

Fully correlated.

All loads are fully correlated.

Fully uncorrelated.

All loads are fully uncorrelated.

Partially correlated.

The degree of correlation is based on the relation between the spatial distance Rij of nodes i and j and the user defined RMIN (Inside radius) and RMAX (Outside radius).

  • Units. Sets the units for the radius.
  • Inside radius. Sets the inner radius (RMIN) which determines the degree of correlation.
  • Outside radius. Sets the outer radius (RMAX) which determines the degree of correlation.

Partial correlation is used for force and pressure excitations.