ABAQUS Keywords Reference Manual  

*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  

Type: Model data

Level: Model  

References:

Required parameter:

CONSTANTS

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

Optional parameters:

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.