Numerical simulation for uniaxial cyclic deformation of discontinuously reinforced metal matrix composites

The cyclic deformation behaviours of SiC particulate reinforced 6061Al alloy composites and aligned short Al2O3 fiber reinforced pure aluminum composites were analyzed under uniaxial cyclic straining and cyclic stressing by finite element code ABAQUS using the single particulate and fiber models of the composites and employing axi-symmetrical 2D six- and eight-node elements, respectively. The ratchetting and mean stress relaxation behaviours occurred under uniaxial cyclic stressing and cyclic straining with non-zero mean stress and mean strain were addressed, respectively, by using a new type of constitutive model with non-linear kinematic hardening rule similar to that developed by Abdel-Karim and Ohno [M. Abdel-Karim, N. Ohno, Int. J. Plasticity 16 (2000) 225] for un-reinforced matrix metals. The particulates and short fibers were assumed as elastic during the whole loading process. Based on the corresponding experimental results of T6-treated SiCp/6061Al composites, the reasonability of the finite element model to simulate the cyclic deformations of the composites was verified first. Then, the cyclic deformation of aligned δ-Al2O3f/Al composites was numerically simulated by the similar finite element model, where the stress transfer between matrix and short fiber occurred under cyclic loading and the effects of fiber volume fraction and fiber aspect ratio on the ratchetting and mean stress relaxation of the composites were discussed in details. Some significant conclusions are obtained, which are useful to establish a constitutive model to describe the cyclic deformation of such composites.