An alternative model for nonlinear stress-strain behaviour of composite materials

Abstract

An alternative model for the Jones-Nelson material model is developed, in which the secant mechanical property is assumed to be a function of the plastic strain energy density of an equivalent linear elastic system which replaces the total strain energy term in the Jones-Nelson model. The present model is capable of treating multiple mechanical property non-linearities which are generally exhibited by fibre-reinforced composite material. The new model is represented in two forms; the basic model and the iterative model. A comparison is carried out in order to correlate strains predicted by the present model with experimental data and other theoretical models cited from the literature. What makes the new model practical is that the plastic strain energy due to loading at any fibre-orientation is not allowed to exceed the fibre direction value obtained from the uniaxial loading test. Hence, the model does not require an extension of behaviour beyond the defined range of strain energy.