EIGVRETRIEVE

Subcase Information Entry The EIGVRETRIEVE command can be used in the Subcase Information section of Modal Frequency Response or Modal Transient Response analysis to retrieve eigenvalue and eigenvector results of a previously run Normal Modes Analysis from an external data file (.eigv).

Format

EIGVRETRIEVE = integer1, integer2, integer3, ...

Definitions

Argument Options Description
integer# <integer>

No default

 Retrieves eigenvalues and eigenvectors from external data files for use in a Modal Frequency Response or Modal Transient Response Analysis.

The external eigenvalue and eigenvector data file name is of the form:

<prefix>.#.eigv

Where,
<prefix>
Is defined by the EIGVNAME I/O Options Entry in the Modal Frequency Response or Modal Transient Response Analysis model.
#
The integer arguments defined on the EIGVSAVE entry. 4

Comments

  1. Only one occurrence of EIGVRETRIEVE per subcase is permitted.
  2. When multiple integer arguments are provided, eigenvalues are retrieved from multiple external data files and combined.
  3. If EIGVRETRIEVE is not present, eigenvalue and eigenvector results are not retrieved from external data files and a normal modes analysis is performed for the modal frequency response or modal transient response analysis subcase.
  4. There are several scenarios under which EIGSAVE and EIGVRETRIEVE can be used:
    • Saving the eigenvector for the full model (using DISP = ALL) in the EIGVSAVE run and then retrieving for the full model (or a subset) in the EIGVRETRIEVE run (using DISP = ALL).
    • Saving the eigenvector for only a part of the model (using DISP = SET ID) in the EIGVSAVE run and then retrieving for the same (or a subset) part of the model (using DISP = SET ID) in the EIGVRETRIEVE run. Saving partial eigenvector in EIGVSAVE run is only valid if the run with EIGVRETRIEVE is a Modal Transient analysis.

    The Degrees of Freedom (DoF) to be retrieved by EIGVRETRIEVE must be the same as or a subset of the DoF provided by corresponding EIGVSAVE entry.

  5. In the case of Modal Transient Analysis
    • If full-model eigenvector is saved and retrieved, EIGVRETRIEVE can be used with Lanczos (EIGRL), AMSES (EIGRA), and AMLS eigen solvers.
    • If partial-model eigenvector is retrieved, EIGVRETRIEVE can be used only with AMSES (EIGRA) and AMLS eigen solvers.

    In the case of Modal Frequency Response Analysis, EIGVRETRIEVE can only be used with the Lanczos eigen solver. Otherwise, an error message will be printed.

    Although an eigen solver is not involved in the EIGVRETRIEVE run, these restrictions are for syntactical reasons.