Consideration of Material Orientation for User-Defined Orthotropic Material Models in LS-DYNA

Author(s):

Brian Fagan

Abstract:

Simulations involving materials with orientation dependence (e.g., composites) must consider the change in material orientation as the component is rotated or deformed. Finite element simulation tools provide two basic frameworks to accommodate the orientation change. One method is to evaluate the material behavior in its current orientation in the global coordinate system. The second method evaluates the constitutive model in the material frame. LS-DYNA typically evaluates anisotropic constitutive models in the latter. This requires evolving the material reference frame and mapping strain rate and prior stress from the global frame to the material frame. This report explores how LS-DYNA handles this evolution and mapping for user-defined material models in explicit simulations. It also provides evaluations of options for controlling the mapping along with providing potential methods for further controlling the mapping.