Residual stress evolution due to cool down in viscoplastic metal matrix composites

Abstract Two issues are considered in the current paper: 1. (1) the effect of cool down from processing temperature on the thermally induced residual stresses in a representative volume element (RVE) of a periodic continuous fiber metal matrix composite monolayer. 2. (2) the initiation of microcracks due to subsequent mechanical loading. A nonlinear incremental finite element program that accounts for thermoviscoplasticity in the matrix is utilized for the micromechanical analysis. The uncoupled heat conduction equation is solved for the spatial temperature distribution in the RVE for given cooling rates. Results indicate that spatial thermal gradients can induce significant stresses at rapid cooling rates. Furthermore, comparisons between thermoelastic and thermoviscoplastic predictions of residual stresses at the interface between the fiber and the matrix demonstrate that incorporating viscoplasticity may be significant in predicting certain damage mechanisms such as interfacial and radial matrix cracking. Finally, average stress-strain curves are obtained for the cases of mechanical loading with or without residual stresses, and predictions are made for the location and time at which interface debonding initiates.