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*DAMPING CONTROLS
Specify damping controls.

This option is used to control the type (viscous, structural) and source of damping (material, global) within the step definition for the following types of analyses in Abaqus/Standard:

Damping can be defined at the material level using visco-elastic behavior or using the *DAMPING option; at the element level using *SPRING, COMPLEX STIFFNESS or *CONNECTOR DAMPING options; for acoustic elements using *ACOUSTIC MEDIUM, VOLUMETRIC DRAG; or using the acoustic impedance definitions (*IMPEDANCE and *SIMPEDANCE). Damping is defined at the global level using *GLOBAL DAMPING. The *DAMPING CONTROLS option controls which of the supplied damping options will participate in the current step or within a substructure.

Use the *SUBSTRUCTURE DAMPING CONTROLS option to control damping for substructure elements (see “Defining substructure damping” in “Using substructures,” Section 10.1.1 of the Abaqus Analysis User's Guide, for details).

Products: Abaqus/Standard  Abaqus/CAE  

Type: Model or history data

Level: Part,  Part instance  

Abaqus/CAE: Supported in the Step module only for substructure generation.

References:

Optional parameters:

LOW FREQUENCY CUTOFF

This parameter is relevant for transient modal analysis only.

Set this parameter equal to the frequency value below which the eigenmodes will not be damped even if damping is requested at the material, element, and/or modal level. This parameter is useful for free structures or for models with secondary base motions.

If this parameter is omitted, the default value is used. The default value is six orders of magnitude smaller than the frequency of the first deformable eigenmode.

If this parameter is included but no value is given, the low frequency cutoff value is given as the square root of the platform precision value.

A negative value can be assigned to allow damping at the low frequency modes.

The parameter units are cycles/time.

STRUCTURAL

Set this parameter equal to ELEMENT to request the structural damping matrix that includes material and/or element damping properties only.

Set this parameter equal to FACTOR to request the structural damping matrix that includes the global damping factor only.

Set this parameter equal to COMBINED to request the structural damping matrix that includes the combination of both ELEMENT and FACTOR.

Set this parameter equal to NONE to exclude the structural damping matrix at this step.

If this parameter is omitted or the option is not used within the step definition, the default uses all structural damping specified at the model and step levels. If both material and global structural damping are specified, the COMBINED damping is used.

If this parameter is omitted or the option is not used as a suboption of *SUBSTRUCTURE PROPERTY, the substructure property uses COMBINED as the default with the structural factor specified under the *DAMPING, STRUCTURAL option.

VISCOUS

Set this parameter equal to ELEMENT to request a viscous damping matrix that includes material and/or element damping properties only.

Set this parameter equal to FACTOR to request a viscous damping matrix that includes the global damping factor only.

Set this parameter equal to COMBINED to request a viscous damping matrix that includes a combination of ELEMENT and FACTOR.

Set this parameter equal to NONE to exclude the viscous damping matrix in this step.

If this parameter is omitted or the option is not used within the step definition, the default uses all viscous damping specified at the model and step levels. If both material and global damping are specified, the COMBINED damping is used.

If this parameter is omitted or the option is not used as a suboption of *SUBSTRUCTURE PROPERTY, the substructure property uses COMBINED as the default with the mass and stiffness proportional Rayleigh damping factors specified under the *DAMPING, ALPHA or BETA option.

There are no data lines associated with this option.