A Damage Mechanics Model of Crack-weakened, Chopped Fiber Composites under Impact Loading

Abstract

A micromechanical approach recently proposed by Lee and Simunovic [Compos, Part B: Engng. 31 (2000) 77] is introduced to develop analytical and numerical models that efficiently predict the behavior of chopped fiber based composites containing microcracks under impact loading. Based on the ensemble-volume averaging process and the first-order effects of eigenstrains due to the existence of chopped fibers and microcracks, an effective yield criterion of the composites is derived. Microcracks in the matrix are considered by employing the Eshelby's equivalence principle and their influence on the stress-strain relations of the composites is investigated. Further, the Weibull's probabilistic function is used to model the varying probability of progressive partial fiber debonding. The developed micromechanical constitutive model is then implemented into the finite element code DYNA3D to perform impact simulation of the composites. Finally, numerical simulations for cantilever beam test and composite contact test are carried out to validate the finite element implementation and predict the impact behavior of composite structures. (C) 2002 Published by Elsevier Science Ltd.