PREDICTION OF STEADY-STATE CREEP-BEHAVIOR OF 2-PHASE COMPOSITES

A simple continuum mechanics-based model has been developed to predict the steady state creep rates of composites containing coarse and rigi d reinforcements from the matrix creep behavior. The model has been de rived on the basis of a unit cell, representative of the composite mic rostructure, which is idealized to a pattern of periodic, cubic inclus ions distributed uniformly in a continuous creeping matrix. Comparison s of the predicted creep rates are made with the experimental data of a number of two phase systems as well as transversely loaded continuou s fiber reinforced composites. A good agreement between the predicted and measured creep rates is seen for most of the systems. However, for some composites, the calculations overestimate the creep rates signif icantly at intermediate volume fractions, typically, 0.3-0.4. It is su ggested that factors such as the differences between the microstructur e of the matrix in the composite and that of the monolithic matrix cou ld be responsible for the differences in the predicted and experimenta lly measured creep behavior. Finally, an assessment of the predictions of the model proposed in this study with rigorous, self-consistent ca lculations as well as finite element simulations has been made.