Parameter Identification of a Viscohyperelastic Constitutive Model for Fiber Reinforced Thermoplastic Composites

Abstract

Short glass fiber reinforced thermoplastic materials exhibit visco-hyperelastic behavior which can be analyzed using different techniques such as instrumented indentation and dynamic mechanical analysis. In the present study, the mechanical response of polyamide (PA) as matrix reinforced by different ratio of glass fiber is studied experimentally and numerically. Force-displacement curves of composite materials are obtained through uniaxial tensile test. Moreover, as viscoelastic behavior takes place due to deviation from static deformation, stress relaxation test is investigated to give a good deal of information about the time dependence of the material’s behavior. Then, a visco-hyperelastic constitutive model is proposed for the behavior of these orthotropic incompressible fiber-reinforced polymer composites. The experimental data are fit in order to obtain the unknown adjustable parameters in constitutive equations using available model in commercial FEM soft-ware, such as ABAQUS. A good agreement is shown between the experimental and numerical results for all compositions. Therefore, it can be noted that the adapted model can accurately predict the nonlinear behavior of molded composites.