*USER MATERIAL

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, $\partial \mathrm{\Delta }\mathit{\sigma }/\partial \mathrm{\Delta }\mathit{\epsilon }$, is not symmetric or when a thermal constitutive model is used and $\partial \mathbf{f}/\partial \left(\partial \theta /\partial \mathbf{x}\right)$ is not symmetric. This parameter causes Abaqus/Standard to use its unsymmetric equation solution procedures.