New material models for nonlinear stress-strain behaviour of composite materials

Abstract

Two new material models are developed in this paper. For an orthotropic material, the nonlinear secant mechanical properties are expressed as a function of the plastic energy density of an equivalent linear-elastic system. The original model represents a direct application to the mechanical property equation, whereas the modified model is an iterative model and is considered as an extrapolation of the original one. The new models can treat multiple mechanical property nonlinearities and predict strains very reasonably at high stress levels. © 1989.