An anisotropic hyperelastic constitutive model for thermoplastic woven composite prepregs

A hyperelastic constitutive model is developed to characterize the anisotropic and large deformation behavior of woven thermoplastic composite prepregs during thermo-forming process. In the model, a strain energy function representing the material behavior of melting prepreg is additively decomposed into three parts nominally representing the energy contributions from the matrix, fiber and their interaction, respectively. The proposed constitutive model is demonstrated on a balanced 2 × 2 twill glass/PP prepreg. The specific forms of the strain energy functions are determined by fitting uni-axial tensile and bias extension tests of the prepregs at melting temperature. The developed model is then applied to simulation of a benchmark double dome thermo-forming, demonstrating that it is highly suitable for predicting the large deformation behavior of woven prepregs during thermo-forming process. The effects of matrix on forming simulation results are also investigated.