Subspace-based steady-state dynamic analysis

A subspace-based steady-state dynamic analysis:

  • is used to calculate the steady-state dynamic linearized response of a system to harmonic excitation;

  • is based on projection of the steady-state dynamic equations on a subspace of selected modes of the undamped system;

  • is a linear perturbation procedure;

  • provides a cost-effective way to include frequency-dependent effects (such as frequency-dependent damping and viscoelastic effects) in the model;

  • allows for nonsymmetric stiffness;

  • requires that an eigenfrequency extraction procedure be performed prior to the steady-state dynamic analysis;

  • can use the high-performance SIM software architecture (see Using the SIM architecture for modal superposition dynamic analyses);

  • is an alternative to direct-solution steady-state dynamic analysis, in which the system's response is calculated in terms of the physical degrees of freedom of the model;

  • can include computation of acoustic contribution factors to help determine the major contributors to acoustic noise;

  • is computationally cheaper than direct-solution steady-state dynamics but more expensive than mode-based steady-state dynamics;

  • is less accurate than direct-solution steady-state analysis, in particular if significant material damping or viscoelasticity with a high loss modulus is present; and

  • is able to bias the excitation frequencies toward the values that generate a response peak.

The following topics are discussed:

Related Topics
Defining an analysis
General and perturbation procedures
About dynamic analysis procedures
Direct-solution steady-state dynamic analysis
Natural frequency extraction
Mode-based steady-state dynamic analysis
In Other Guides
Configuring a subspace-based steady-state dynamic analysis