Modeling nonlinear rate dependent behaviors of composite laminates

Abstract

This study aims to propose a simple explicit model for predicting the nonlinear rate dependent behaviors of composite laminates. Using one parameter plastic potential to describe the flow rule, the viscoplasticity model is expressed as a single master effective stress-effective plastic strain curve in the form of a power law with a rate dependent amplitude. Based on the viscoplasticity model together with the laminated plate theory, the incremental form of the constitutive formulation is derived to model the nonlinear rate dependent behaviors of composite laminates. Symmetric glass/ epoxy and graphite/epoxy composite laminates were tested at three different strain rates and the experimental results were then compared with the model predictions. It was indicated that the proposed constitutive model is effective in characterizing the nonlinear rate dependent behaviors of composite laminates at strain levels up to 1%.