Natural frequency extraction

The frequency extraction procedure:

  • performs eigenvalue extraction to calculate the natural frequencies and the corresponding mode shapes of a system;

  • will include initial stress and load stiffness effects due to preloads and initial conditions if geometric nonlinearity is accounted for in the base state, so that small vibrations of a preloaded structure can be modeled;

  • will compute residual modes if requested;

  • is a linear perturbation procedure;

  • can be performed using the traditional Abaqus software architecture if appropriate, but the high-performance SIM architecture (see Using the SIM architecture for modal superposition dynamic analyses) is used as the default; and

  • solves the eigenfrequency problem only for symmetric mass and stiffness matrices; the complex eigenfrequency solver must be used if unsymmetric contributions, such as the load stiffness, are needed.

The following topics are discussed:

Related Topics
Defining an analysis
General and perturbation procedures
About dynamic analysis procedures
In Other Guides
Configuring a frequency procedure