An experimental study of elastic-plastic behavior of a fibrous boron-aluminum composite

Abstract

Initial and subsequent yield surfaces and plastic strains were found for a fibrous boron-aluminum composite, and for the aluminum matrix, under many plane stress loading programs. The experiments were performed on axially reinforced tubular specimens, and on similar matrix specimens, which were loaded by increments of axial force, torque, and internal pressure. The results show that the composite yield surfaces of this particular system have extensive flat segments associated with a matrix-dominated deformation mode, as well as convex segments which correspond to a fiber-dominated mode. A definite connection has been established between composite and matrix hardening. The latter is dominated by translation of the yield surface in the direction of the applied stress increment. Apart from possibly large changes in size, which may be attributed in part to observed distortions of subsequent matrix yield surfaces, this aspect of matrix hardening leads to the conclusion that the composite yield surfaces must also translate in the direction of the applied stress increment. This was confirmed by the experimental results, but exceptions were anticipated and detected during loading at the flat segments and at certain vertices.