Optional parameters – ABAQUS Volume II: I–Z User Manual

Page 401

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*SELECT EIGENMODES

18.7

*SELECT EIGENMODES:

Select the modes to be used in a modal dynamic analysis.

This option selects the modes to be used in a dynamic analysis based on modes or in a complex eigenvalue
extraction analysis. Only one option per step can be used. If this option is not used, all modes extracted in
the prior *FREQUENCY step will be used, including residual modes if they were activated.

Product:

ABAQUS/Standard

Type:

History data

Level:

Step

References:

•

“Implicit dynamic analysis using direct integration,” Section 6.3.2 of the ABAQUS Analysis User’s
Manual

•

“Complex eigenvalue extraction,” Section 6.3.6 of the ABAQUS Analysis User’s Manual

•

“Transient modal dynamic analysis,” Section 6.3.7 of the ABAQUS Analysis User’s Manual

•

“Mode-based steady-state dynamic analysis,” Section 6.3.8 of the ABAQUS Analysis User’s Manual

•

“Subspace-based steady-state dynamic analysis,” Section 6.3.9 of the ABAQUS Analysis User’s Manual

•

“Response spectrum analysis,” Section 6.3.10 of the ABAQUS Analysis User’s Manual

•

“Random response analysis,” Section 6.3.11 of the ABAQUS Analysis User’s Manual

•

*MODAL DAMPING

Optional parameters:

GENERATE

If this parameter is included, each data line should give a first mode,

; a last mode,

; and the

increment in mode numbers between these modes, i. Then all modes going from

to

in steps

of i will be added to the set. i must be an integer such that

is a whole number (not a

fraction).

This parameter can be used only with DEFINITION=MODE NUMBERS.

DEFINITION

Set DEFINITION=MODE NUMBERS (default) to indicate that the selected modes are given as a
collection of mode numbers.

Set DEFINITION= FREQUENCY RANGE to indicate that the modes are selected from the

specified frequency ranges including frequency boundaries. Frequency ranges can be discontinuous.

If both the *MODAL DAMPING and *SELECT EIGENMODES options are used in the same

step, the DEFINITION parameter must be set equal to the same value in both options.

18.7–1

ABAQUS Version 6.1

Module: ID:

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