Numerical Fracture Analysis for the Fracture Mechanisms of Stress-Induced Microcrack-Toughening

Abstract

Stress-induced microcrack toughening is studied through the numerical fracture mechanics with the finite element method. In our numerical model, the stress-induced microcrack zone is represented by the local reduction of the Young's modulus. The microcrack toughening is discussed in terms of the changes in the Young's modulus, Poisson's ratio, and the dimension and the shape of the process zone. The reduction of the local stress intensity factor at the crack-tip, K_I^TIP, results in toughening. The reduction of K_I^TIP is proportional to the decrease in the Young's modulus, and enhanced through the decrease in the Poisson's ratio. The K_I^TIP reduces significantly with increasing the dimension of the process zone, and then followed by saturation. This toughening effect diminishes for an infinitely large process zone. The shape of the process zone makes an important influence on stress shielding, as well.