Effective elastoplastic behavior of ductile matric composites containing randomly located aligned circular fibers

Based on the micromechanical framework and the second-order transverse effective elastic moduli of fiber-reinforced composites derived by Ju and Zhang [Int. J. Solids Struct. 35 (1996) 941], effective elasto-(visco-)plastic behavior of two-phase unidirectional fiber-reinforced ductile matrix composites (FRDMCs) is studied in detail. The circular fibers are assumed to be elastic and unidirectionally aligned while the matrix phase can be either elastic or plastic, depending on the local stress state and effective yield criteria. Furthermore, the ensemble-averaged stress norm is constructed based on the probabilistic distribution of circular fibers, pairwise fiber interactions and the ensemble-area averaging procedure. Together with the plastic flow rule and hardening law postulated in continuum plasticity, the aforementioned stress norm is employed to characterize the overall yield criteria which determine the elastoplastic behavior of FRDMCs under general transverse plane-strain loading and unloading histories. As a special case, the initial effective yield criteria for incompressible ductile matrix containing many unidirectionally aligned cylindrical voids are also derived. In addition, the overall elasto-viscoplastic behavior of FRDMCs is investigated based on the Duvaut-Lions viscoplasticity. Finally, comparison between our theoretical predictions and the available experimental data for FRDMCs is performed to illustrate the capability of the proposed framework. (C) 2001 Elsevier Science Ltd. All rights reserved.