Micromechanical elastoplastic damage modeling of progressive interfacial arc debonding for fiber reinforced composites

This study presents a new micromechanical elastoplastic progressive damage model to predict the effective transverse mechanical behavior and interfacial arc microcrack evolution of fiber-reinforced composites. The partial debonding process at the fiber-matrix interfaces is represented by the growing debonding angles of arc microcracks. Progressive partially debonded cylindrical isotropic fibers are replaced by equivalent orthotropic yet perfectly bonded elastic cylindrical fibers. The equivalent orthotropic elastic moduli are constructed to characterize the reduction of the load-transfer capacity in the debonded directions. The effective elastic moduli of four-phase composites are derived by using a micromechanical formulation. In order to characterize the overall transverse elastoplastic damage behavior, an effective yield criterion is derived on the basis of the ensemble-area averaging procedure and the first-order effects of eigenstrains upon yielding. The proposed effective yield criterion, coupling with the overall plastic flow rule and the hardening law, comprises the analytical framework for the prediction of effective elastoplastic-damage responses of ductile matrix composites containing randomly located yet aligned cylindrical fibers. The Weibull's probabilistic function is utilized to characterize the varying probability of progressive interfacial arc microcracks, governed by the internal stresses of fibers and the interfacial bonding strength. The proposed micromechanical elastoplastic-damage model is then applied to the transverse uniaxial and transverse biaxial tensile loading with varied stress ratios. Comparisons between the present predictions and available experimental data, as well as other numerical simulations, are performed to elucidate the potential of the proposed formulation.