Physics-Based Multiscale Creep Strain and Creep Rupture Modeling for Composite Materials

In this study, a novel multiscale combined creep strain and creep rupture model is proposed. By comparing to experimental data, it was shown that the model provides accurate creep rupture predictions for unidirectional off-axis specimens. The creep strain model provides accurate predictions within the confines of the restrictions used in its development. This coupled model was incorporated into a progressive failure finite-element simulation so that the effects of load redistribution could be considered, which tended to increase the life of the part when strain gradients were present. The finite-element implementation also allowed for the consideration of realistic geometries resulting in complex stress states. By considering a perfectly flat specimen and one containing worst-case thickness variation, experimental open-hole creep rupture data was accurately bounded. This suggests that, by quantifying material defects, realistic lifetime predictions can be made, and an estimate of scatter can be acquired.