A user-defined orientation is used to define a local coordinate system for:

  • definition of material properties—for example, anisotropic materials or jointed materials (a local coordinate system must be defined if anisotropic material properties are defined for solid elements);

  • definition of local material directions, such as the in-plane fill and warp yarn directions of a fabric material or the fiber directions of anisotropic hyperelastic materials;

  • definition of rebars in shell, membrane, and surface elements;

  • definition of rotary inertia and connector elements;

  • definition of coupling constraints;

  • definition of loading directions for distributed general tractions, shear tractions, and general edge loads;

  • definition of local tangent directions for contact in Abaqus/Standard;

  • material calculations at integration points;

  • output of components of stress, strain, and element section force; and

  • definition of a local system of rigid body motion directions for inertia relief in Abaqus/Standard.

A user-defined orientation cannot be used:

Considerable generality is provided in the way the local system can be defined, since this system must often change from point to point because of the shape and construction of the structure being modeled. You can define the local orientation directly. The direct data methods provided in Abaqus are intended to give sufficient generality to model most cases easily: they are particularly useful for regular geometry. Distributions (Distribution definition) can be used to define spatially varying local coordinate systems for solid continuum, shell, and membrane (in Abaqus/Standard) elements directly for arbitrary geometries.

In Abaqus/Standard you can alternatively define the local orientation in user subroutine ORIENT.

The following topics are discussed:

Related Topics
Distribution definition
In Other Guides
About the material library
Material data definition
Fabric material behavior
Distributed loads
Kinematic coupling constraints
Coupling constraints
Inertia relief
Creating datum coordinate systems