Theory of Plasticity for a Class of Inclusion and Fiber-Reinforced Composites

Abstract

Based on the theoretical framework recently established by Tandon and Weng (1988), a multiaxial theory of plasticity is developed for a class of composites containing unidirectionally aligned spheroidal inclusions. The aspect ratio of inclusions may range from that of a thin disk all the way to that of a continuous fiber, and its influence on the transversely isotropic elastoplastic behavior of the composite is investigated. Under a combined stress the secant moduli of the composite and the average stress concentration factors of the matrix are derived. It is shown that the yield condition of the composite generally depends on the hydrostatic pressure, contributing most significantly for the disk and fiber-reinforced cases. Both the initial yield stress and the work-hardening modulus of the anisotropic composite are also seen to be strongly influenced by the shape of inclusions; the disks are found to be most effective in the transverse plane but the fibers are so along the axial direction. Finally, a rather detailed account on the elastoplastic behavior of fiber-reinforced composites is given, and a comparison of the stress-strain curve with experiment is also demonstrated.