Effect of a Microdefect ahead of a Main Crack on Strength of Solids : 3rd Report, Main Crack-Slip Band Interaction Model and Its Application to Microcrack Growth

In the present paper, in order to elucidate micromechanically the crack length dependence of threshold stress for no crack growth in steel, we propose a main crack-slip band interaction model which consists of a main crack, a dislocation free zone, and a slip band. Analyzing the above model by the method based on the continuously distributed theory of dislocations, we obtain the distribution functions and the stress intensity factors K both at the tip of the main crack and the slip band in a closed form. Using these K values, we can elucidate the effective range of the above interaction model and the crack shielding effect by a slip band. Furthermore, the analytical expression for the crack length dependence of threshold stress for no crack growth, which involves the effect of the crack length and grain size, can be obtained successfully by using the present model.