An Experimentally Validated Hyper-Viscoelastic Model for the Bending Responses of Pre-Impregnated Tapes Under Processing Conditions

Abstract

Compaction of pre-impregnated fiber sheets (prepregs) is crucial to the formation of defects such as wrinkles and void. This study presents an anisotropic hyper-viscoelastic constitutive model to predict the compaction deformation and force of prepregs considering the influence of temperature on resin behaviors. The entire stack of individual prepregs is homogenized as an anisotropic continuous material whose strain energy density function is developed considering normal, shear, and coupling between normal behaviors. The proposed constitutive model integrates prepreg relaxation responses through generalized Maxwell models. The proposed novel constitutive model was implemented in the commercial Finite Element Analysis (FEA) software Abaqus as a user-defined material subroutine, UMAT. The modeling parameters were characterized by a discrete micromechanics model. The modeling approach was further applied to simulate a stepwise compaction process of carbon fiber/polyamide 6 prepregs to demonstrate the predictive capability.