A Constitutive Model for Fiber-reinforced Polymer Composites

A constitutive model for fibrous polymer composites was established based on an elastic—plastic approach. The proposed potential function is a linear combination of functions related to deviatoric and dilatational deformations. A unidirectional carbon/epoxy composite, AS4/3501-6, and a woven-glass/vinylester composite were fabricated and tested under quasi-static off-axis tension and compression and used in developing and verifying the model. Model parameters were determined from the off-axis test results. Stress—strain curves predicted by the model were in good agreement with experimental results. The constitutive model established can describe the nonlinear orthotropic mechanical behavior of the composites, and it accounts as well for their tension—compression behavior.