AN ITERATIVE APPROACH TO MECHANICAL-PROPERTIES OF MMCS AT THE ONSET OF PLASTIC-DEFORMATION

The current work presents a generalized Eshelby model allowing interac tion among reinforcing particles under a Mori-Tanaka like scheme. Diff erent aspect ratios and geometries are studied in the elastic and inci pient elasto-plastic regime for a model SiC-Al composite. The fibers a re taken as purely elastic and the matrix is regarded elastic perfectl y plastic responding to a Von Mises yield criterion. The phenomenon of plastic localization in the vicinities of the inclusions is carefully described for different reinforcement volume fractions and thermo-mec hanical loading. Equivalent stress, hydrostatic pressure and elastic a nd plastic strains are depicted as contour levels around a representat ive inclusion. Effective coefficients of thermal expansion of composit es are calculated both under purely elastic composite response and at the onset of plastic localized deformation. The influence of plastic s train over those effective coefficients is shown to be detectable. The simulated stress-strain curves show the influence of interaction stre sses over macroscopic yield stress by isolating this phenomenon from m atrix hardening. Accumulated elastic energies and plastic work are cal culated to show the different nature of purely thermal and mechanical loads. (C) 1997 Elsevier Science S.A.