Fracture Mechanics of Composites with Residual Thermal Stresses

The problem of calculating the energy release rate for crack growth in an arbitrary composite in the presence of residual stresses is considered. First, a general expression is given for arbitrary, mixed traction and displacement boundary conditions. This general result is then applied to a series of specific problems including statistically homogeneous composites under traction or displacement boundary conditions, delamination of double cantilever beam specimens, and microcracking in the transverse plies of laminates. In many examples, the energy release rate in the presence of residual stresses can be reduced to finding the effect of damage on the effective mechanical properties of the composite. Because these effective properties can be evaluated by isothermal stress analysis, the effect of residual stresses on the energy release rate can be evaluated without recourse to any thermal elasticity stress analyses.