Energy-based delamination theory for biaxial loading in the presence of thermal stresses

The boundary element method (BEM) has been used to investigate energy release rates for constrained conditions for a range of ply crack densities, both in the presence and absence of thermal residual stresses, for a special case where the delamination tips are mid-way between neighbouring ply cracks. BEM results show a slight dependence of the energy release rate on ply crack separation, and predictions for the maximum ply crack separation considered are within 1.6% of the exact limiting analytical predictions valid for infinite separation. This agreement indicates the validity of both the analytical methods used, and the numerical analysis based on the BEM.