LAUSR

Abstract During the past couple of decades, modern fracture criteria have been developed based on a crack-tip material length scale so-called the critical distance, where the critical energy/stress/strain parameter required for the crack propagation is measured. However, in most cases, the critical distance has been considered as a material parameter measured under pure mode I crack tip displacements and independent of the mode mixity. In this paper, the concept of “effective critical distances” is introduced by considering the effect of mode mixity on the measured critical distances via a strain-based approach to construct a novel mixed-mode I/II/III brittle fracture criterion (ECD-SN criterion). Along with the traditional stress and energy-based criteria of MPS, and SED, the proposed criterion is examined by predicting the experimental data reported in the literature for the mixed-mode I/II/III fracture toughness and fracture angles. Results reveal superior estimates of the test data by the ECD-SN criterion as compared to the traditional criteria highlighting the necessity of adopting an “effective critical distance” in the three-dimensional brittle fracture theories.