ABAQUS Volume II: I–Z - Manual (Page 377)

*ROTARY INERTIA
17.20 *ROTARY INERTIA: Define rigid body rotary inertia.
This option is used to define rigid body rotary inertia values associated with ROTARYI elements.
It is also used in ABAQUS/Standard analyses to define mass proportional damping (for direct-integration
dynamic analysis) and composite damping (for modal dynamic analysis) associated with ROTARYI elements.
Products: ABAQUS/Standard ABAQUS/Explicit
Type: Model data
Level: Part, Part instance, Assembly
Reference:
•
“Rotary inertia,” Section 24.2.1 of the ABAQUS Analysis User’s Manual
Required parameter:
ELSET
Set this parameter equal to the name of the element set containing the ROTARYI elements for which
the value is being given.
Optional parameters:
ALPHA
This parameter applies only to ABAQUS/Standard analyses.
Set this parameter equal to the factor to create inertia proportional damping for the
ROTARYI elements when used in direct-integration dynamics. This value is ignored in modal
dynamics. The default is 0.0.
COMPOSITE
This parameter applies only to ABAQUS/Standard analyses.
Set this parameter equal to the fraction of critical damping to be used with the ROTARYI
elements when calculating composite damping factors for the modes when used in modal dynamics.
This value is ignored in direct-integration dynamics. The default is 0.0.
ORIENTATION
Set this parameter equal to the name of an *ORIENTATION option (“Orientations,” Section 2.2.5
of the ABAQUS Analysis User’s Manual) that is being used to define the directions of the local axes
for which the rotary inertia values are being given. If the ORIENTATION parameter is omitted, it
is assumed that the components of the inertia tensor are being given with respect to the global axes;
i.e., the global and local inertia axes coincide.
17.20–1
ABAQUS Version 6.1 Module: ID:
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