*SPRING

Define spring behavior.

This option is used to define the spring behavior for spring elements. It is also used to assign a structural damping factor to form the imaginary part of the spring stiffness matrix. The imaginary stiffness represents an element-level damping contribution to the frequency domain dynamic equations and to the time domain mode-based dynamic analyses that support nondiagonal damping (see Modal dynamic analysis).

In Abaqus/Standard analyses it is also used to define the spring behavior for ITS and JOINTC elements. If the SPRING option is being used to define part of the behavior of ITS or JOINTC elements, it must be used in conjunction with the ITS or JOINT options and the ELSET and ORIENTATION parameters should not be used.

This page discusses:

See Also
In Other Guides
Springs
Flexible Joint Element
Tube Support Elements

ProductsAbaqus/StandardAbaqus/Explicit

TypeModel data

LevelPartPart instanceAssembly

Required parameter if the behavior of spring elements is being defined

ELSET

Set this parameter equal to the name of the element set containing the spring elements for which this behavior is being defined.

Optional parameters

COMPLEX STIFFNESS

This parameter is relevant in direct-solution and subspace-based steady-state analyses and in mode-based analyses with FREQUENCY, DAMPING PROJECTION=ON in Abaqus/Standard that support nondiagonal damping.

Include this parameter to define both the real and imaginary parts of the stiffness. The imaginary part represents structural damping.

If this parameter is omitted, the default is real stiffness only.

DEPENDENCIES

Set this parameter equal to the number of field variable dependencies included in the definition of the real spring stiffness data, in addition to temperature. If this parameter is omitted, it is assumed that the spring stiffness is independent of field variables. See Using the DEPENDENCIES parameters to define field variable dependence in Material Data Definition for more information.

NONLINEAR

Include this parameter to define nonlinear spring behavior. Omit this parameter to define linear spring behavior.

ORIENTATION

This parameter applies only to Abaqus/Standard analyses.

If the option is being used to define the behavior of SPRING1 or SPRING2 elements, this parameter can be used to refer to an orientation definition so that the spring is acting in a local system. Set this parameter equal to the name of the ORIENTATION definition (Orientations).

RTOL

This parameter applies only to Abaqus/Explicit analyses.

Set this parameter equal to the tolerance to be used for regularizing the material data. The default is RTOL=0.03. See Material Data Definition for a discussion of data regularization.

Data lines to define linear spring behavior for SPRINGA or ITS elements

First line

  1. Enter a blank line.

Second line

  1. Spring stiffness (force per relative displacement).

  2. Frequency (in cycles per time). Applicable only for STEADY STATE DYNAMICS, DIRECT; STEADY STATE DYNAMICS, SUBSPACE PROJECTION; and STEADY STATE DYNAMICS and MODAL DYNAMIC analyses that support nondiagonal damping.

  3. Temperature.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the spring stiffness as a function of frequency, temperature, and other predefined field variables.

Data lines to define nonlinear spring behavior for SPRINGA or ITS elements

First line

  1. Enter a blank line.

Second line

  1. Force.

  2. Relative displacement.

  3. Temperature.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the spring stiffness as a function of temperature and other predefined field variables.

Data lines to define linear spring behavior for SPRING1, SPRING2, or JOINTC elements

First line

  1. Degree of freedom with which the springs are associated at their first nodes or, for JOINTC elements, the degree of freedom for which the spring behavior is being defined.

  2. For SPRING2 elements give the degree of freedom with which the springs are associated at their second nodes.

If the ORIENTATION parameter is included on the SPRING option when defining spring elements or on the JOINT option when defining joint elements, the degrees of freedom specified here are in the local system defined by the ORIENTATION option referenced.

Second line

  1. Real spring stiffness (force per relative displacement).

  2. Frequency (in cycles per time). Applicable only for STEADY STATE DYNAMICS, DIRECT; STEADY STATE DYNAMICS, SUBSPACE PROJECTION; and STEADY STATE DYNAMICS and MODAL DYNAMIC analyses that support nondiagonal damping.

  3. Temperature.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the spring stiffness as a function of frequency, temperature, and other predefined field variables.

Data lines to define nonlinear spring behavior for SPRING1, SPRING2, or JOINTC elements

First line

  1. Degree of freedom with which the springs are associated at their first nodes or, for JOINTC elements, the degree of freedom for which the spring behavior is being defined.

  2. For SPRING2 elements give the degree of freedom with which the springs are associated at their second nodes.

If the ORIENTATION parameter is included on the SPRING option when defining spring elements or on the JOINT option when defining joint elements, the degrees of freedom specified here are in the local system defined by the ORIENTATION option referenced.

Second line

  1. Force.

  2. Relative displacement.

  3. Temperature.

  4. First field variable.

  5. Second field variable.

  6. Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

  1. Sixth field variable.

  2. Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the spring stiffness as a function of temperature and other predefined field variables.

Data lines to define linear spring behavior for SPRINGA elements with COMPLEX STIFFNESS

First line

  1. Enter a blank line.

Second line

  1. Real spring stiffness (force per relative displacement).

  2. Structural damping factor.

  3. Frequency (in cycles per time). Applicable only for STEADY STATE DYNAMICS, DIRECT; STEADY STATE DYNAMICS, SUBSPACE PROJECTION; and STEADY STATE DYNAMICS and MODAL DYNAMIC analyses that support nondiagonal damping.

Repeat this set of data lines as often as necessary to define the spring stiffness and structural damping factor as a function of frequency.

Data lines to define linear spring behavior for SPRING1 and SPRING2 elements with COMPLEX STIFFNESS

First line

  1. Degree of freedom with which the springs are associated at their first nodes.

  2. For SPRING2 elements give the degree of freedom with which the springs are associated at their second nodes.

If the ORIENTATION parameter is included on the SPRING option when defining spring elements, the degrees of freedom specified here are in the local system defined by the ORIENTATION option referenced.

Second line

  1. Real spring stiffness (force per relative displacement).

  2. Structural damping factor.

  3. Frequency (in cycles per time). Applicable only for STEADY STATE DYNAMICS, DIRECT; STEADY STATE DYNAMICS, SUBSPACE PROJECTION; and STEADY STATE DYNAMICS and MODAL DYNAMIC analyses that support nondiagonal damping.

Repeat this set of data lines as often as necessary to define the spring stiffness and the structural damping factor as a function of frequency.