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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