Abstract: The non-singular constant stress term (T-stress) around the crack tip remarkably affects the fracture characteristics of brittle or quasi-brittle materials, and it is also closely related to the shape and size of the plastic zone near the crack tip. In order to explore the influence of T-stress on the I~II mixed mode fracture characteristics of brittle or quasi-brittle materials, the generalized maximum tangential strain (GMTSN) criterion, which considers the effect of T-stress, has been proposed in our previous research. In this paper, the further study on the effects of T-stress, critical distance r₀ and Poisson's ratio ν on the crack propagation path and the fracture resistance for central cracked Brazilian disc (CCBD) specimens have been carried out according to the GMTSN criterion. Moreover, the GMTSN criterion is used to predict the test results obtained with CCBD specimens. The results indicate that the T-stress and Poisson's ratio have a remarkable influence on the mixed mode fracture resistance based on the GMTSN criterion. When compared with the traditional maximum tangential strain (MTSN) criterion, a negative T-stress in a CCBD specimen always decreases the absolute value of the fracture initiation angle; however, the value of critical stress intensity factor is increased for negative values of T-stress. Theoretical values based on the GMTSN criterion, which considers the effect of T-stress, are in very good agreement with the test results. Moreover, the GMTSN criterion provides a better prediction for pure mode II when compared with the generalized maximum tangential stress (GMTS) criterion.

Key words: I~II mixed mode fracture, fracture toughness, T-stress, generalized maximum tangential strain criterion, central cracked Brazilian disc