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*USER MATERIAL
Define material constants for use in subroutine UMAT, UMATHT, or VUMAT.

This option is used to input material constants for use in a user-defined mechanical model (user subroutine UMAT in Abaqus/Standard or user subroutine VUMAT in Abaqus/Explicit). In Abaqus/Standard it is also used to input material constants for use in a user-defined thermal material model (user subroutine UMATHT).

Products: Abaqus/Standard  Abaqus/Explicit  Abaqus/CAE  

Type: Model data

Level: Model  

Abaqus/CAE: Property module

References:

Required parameter:

CONSTANTS

Set this parameter equal to the number of constants being entered.

Optional parameters:

HYBRID FORMULATION

This parameter applies only to Abaqus/Standard analyses.

Set HYBRID FORMULATION=INCREMENTAL (default) to use an incremental Lagrange multiplier–based formulation with hybrid elements.

Set HYBRID FORMULATION=TOTAL to use a total Lagrange multiplier–based formulation with hybrid elements.

Set HYBRID FORMULATION=INCOMPRESSIBLE to define an incompressible material response with hybrid elements.

TYPE

This parameter applies only to Abaqus/Standard analyses.

Set TYPE=MECHANICAL (default) if the constants are used in defining the mechanical behavior of the material.

Set TYPE=THERMAL if the constants are used in defining the thermal constitutive behavior of the material.

If both the user-defined mechanical and the user-defined thermal behavior of the material are being modeled, the *USER MATERIAL option should be repeated in the material data block such that each value of the TYPE parameter is used.

UNSYMM

This parameter applies only to Abaqus/Standard analyses.

Include this parameter if the material stiffness matrix, , is not symmetric or when a thermal constitutive model is used and is not symmetric. This parameter causes Abaqus/Standard to use its unsymmetric equation solution procedures.

Data lines to define material constants: 

First line:

  1. Give the material constants, eight per line.

Repeat this data line as often as necessary to define all material constants.