User subroutine to define fabric material behavior.

Warning: The use of this user subroutine generally requires considerable expertise. You are cautioned that the implementation of any realistic constitutive model requires extensive development and testing. Initial testing on a single-element model with prescribed traction loading is strongly recommended.

User subroutine VFABRIC:

  • is used to define the mechanical constitutive behavior of a fabric material in the plane of the fabric;

  • is valid for materials that exhibit two “structural” directions that may not be orthogonal to each other with deformation;

  • is used to update the nominal fabric stresses for a given nominal fabric strain where the direct strains are defined as the nominal strain measured along the two yarn directions of the fabric and the engineering shear strain is defined as the drop in the angle between the two yarn directions going from the reference configuration to the current configuration;

  • can be used with elements under plane stress conditions;

  • will be called for blocks of material calculation points for which the material is defined in a user subroutine (Material data definition);

  • can use and update solution-dependent state variables;

  • can use any field variables that are passed in; and

  • cannot be used in an adiabatic analysis.

The following topics are discussed:

Related Topics
In Other Guides
Fabric material behavior