A weibull brittle failure model for biaxial loading of a notched composite material

A brittle failure model based on the Weibull theory is developed for a plate subjected to biaxial stresses. The failure model is based on an opening mode (mode I) failure propagating outward from an existing through-hole. This model leads to Weibull integrals which are simplified to one dimension in order to evaluate the highest risk-to-failure volume. The Weibull integrals are evaluated numerically for an isotropic plate with a center through-hole with a searching scheme to find the most likely angle of fracture. When compared with experimental results, the Weibull integrals yield generally conservative estimates of notched strength, predicting a more rapid degradation of strength in the presence of a notch than is actually experienced. The integrals also correctly predict the strengthening effect due to the biaxial tension.