29. Fiber Cracking and Elastoplastic Damage Behavior of Fiber Reinforced Metal Matrix Composites

To predict the overall transverse mechanical behavior and damage evolutions of cylindrical fiber-reinforced ductile composites with fiber cracking, an innovative micromechanical multi-level elastoplastic evolutionary damage framework is proposed. Progressively cracked fibers are modeled by using the double-inclusion theory. The effective elastic moduli of 3-phase composites, consisting of a matrix, randomly located yet monotonically aligned cylindrical uncracked fibers and cracked fibers, are derived by using a micromechanical formulation. A micromechanical effective yield criterion is derived based on the ensemble-area averaging process and the first-order effects of eigenstrains to characterize the homogenized elastoplastic behavior. The resulting effective yield criterion, together with the overall associative plastic flow rule and the hardening law, constitutes the analytical framework for the estimation of effective transverse elastoplastic damage responses of ductile composites containing both uncracked and cracked fibers. An evolutionary fiber cracking process, governed by the internal stresses and the fracture strength of fibers, is incorporated into the proposed work. The Weibull’s probabilistic distribution is employed to describe the varying probability of fiber cracking. Further, systematic numerical simulations are presented to illustrate the potential of the proposed methodology.