Effective elastoplastic behavior of metal matrix composites containing randomly located aligned spheroidal inhomogeneities. Part I: micromechanics-based formulation

Based on the framework of Ju and Chen (Ju, J.W., Chen, T.M., 1994. J. Engng. Mater. Tech. ASME 116, 310-318) and Ju and Tseng (Ju, J.W., Tseng, K.H., 1996. Int. J. Solids Struct. 33, 4267-4291; Ju, J.W., Tseng, K.H., 1997. J. Engng. ASCE 123, 260-266), we study the effective elastoplastic behavior of two-phase metal matrix composites (MMCs) containing randomly located yet unidirectionally aligned spheroidal inhomogeneities. Specifically, the particle phase is assumed to be linearly elastic and the matrix phase is elastoplastic. The ensemble-volume averaging procedure is employed to micromechanically derive the effective yield function of MMCs based on the probabilistic spatial distribution of aligned spheroidal particles and the particle-matrix influences. The transversely isotropic effective elasticity tensor is explicitly derived. Further, the associative plastic flow rule and the isotropic hardening law are postulated according to the continuum plasticity. As a result, we can characterize the overall elastoplastic stress-strain responses of aligned spheroid-reinforced MMCs under three-dimensional loading and unloading histories. The overall elastoplastic continuum tangent tensor of MMCs is also explicitly presented. (C) 2000 Elsevier Science Ltd. All rights reserved.