Towards a micromechanics based inelastic and damage modeling of composites

Micromechanics based models are considered for application to viscoplasticity and damage in metal matrix composites. The method proposes a continuation and development of Dvorakʹs transformation field analysis, considering piecewise uniform eigenstrains in each material phase. Standard applications of the method for a two-phase model (only one sub-volume per phase) deliver too stiff responses. Two modifications are proposed that improve considerably the overall stress–strain response, at least for materials sustaining a linear hardening under large strains. Introduction of damage effects in the TFA method is considered, within the CDM framework, using two modeling approaches: the “Direct Simplified Model”, using only two damaged phases, and the “Generalized Eigenstrain Model”, with more degrees of freedom, that allows the description of interfacial damage. The different aspects of the proposed methods are systematically checked by comparing with finite element unit cell analyses, made through periodic homogenization assumptions, for a SiC/Ti unidirectional MMC.