A simple model to explain transferability of crack tip opening angle

A stable crack growth model based on critical crack tip opening angle (CTOA) is proposed. This model considers the growing crack opening profile as corresponding stationary crack opening profile minus plastic wake profile. A relationship between CTOA and stationary crack tip opening displacement is established. Relations between CTOA and K-R curves, J integral are then obtained from this relationship and the crack growth model is thus verified. Based on this model, the transferability of CTOA is discussed by dimensional analysis. The critical CTOA is independent of initial crack size, structural size, and structural configuration for a given material and stress state if the plastic zone stress distribution is invariable. A method to predict residual strength based on a critical CTOA is proposed and rudimentary verification is performed using previously published fracture test results.