When you configure a frequency step, you must choose one of the following
eigenvalue extraction methods:
- Lanczos
-
The Lanczos method is the default method because it has general
capabilities. However, this method is usually slower than the
AMS method. For more information, see
Lanczos eigensolver,
and
Eigenvalue extraction.
For detailed instructions on configuring settings for the Lanczos eigenvalue
extraction method, see
Using the Lanczos eigensolver for a frequency extraction procedure.”
- Automatic
multi-level substructuring (AMS)
-
The AMS method is an add-on analysis
capability for
Abaqus/Standard.
The AMS method is faster than the Lanczos
method, particularly when you require a large number of eigenmodes for a system
with many degrees of freedom. However, the AMS
method has several limitations. For more information, see
Automatic multi-level substructuring (AMS) eigensolver.
For detailed instructions on configuring settings for the
AMS extraction method, see
Using the AMS eigensolver for a frequency extraction procedure.”
- Subspace
iteration
-
For the subspace iteration procedure you need only specify the number of
eigenvalues required;
Abaqus/Standard
chooses a suitable number of vectors for the iteration. You can also specify
the maximum frequency of interest;
Abaqus/Standard
extracts eigenvalues until either the requested number of eigenvalues has been
extracted or the last frequency extracted exceeds the maximum frequency of
interest. For more information, see
Eigenvalue extraction.
For detailed instructions on configuring settings for the subspace iteration
extraction method, see
Using the subspace iteration eigensolver for a frequency extraction procedure.”
For background information on frequency extraction procedures, see
Natural frequency extraction.