A NONLOCAL DAMAGE APPROACH TO ANALYSIS OF THE FRACTURE PROCESS ZONE

A two-zone fracture process model with a crack-bridging zone (CBZ) and a microcracking zone (MCZ) is proposed to describe the fracture proce ss around the tip of a macrocrack. A nonlocal damage approach based on previous work is used to determine the size of the fracture process z one (FPZ). The experimental analysis given by Horii and Ichinomiya [In t. J. Fracture 51, 19-29 (1991)] supports the proposal that the existe nce of the crack bridging effect brings out an increase in load-carryi ng capacity of materials, whereas microcracking leads to the deteriora tion of the capacity. Based on the above and utilizing Westergaard's c omplex function, the distribution functions of stress and damage in th e FPZ are given. Applying these to the concrete-like material mortar, we can determine the distribution functions of stress and damage in th e FPZ if load and crack opening displacement (COD) at a point are give n. Additionally, a nonlocal damage failure criterion is proposed to ju dge the propagation of the macrocrack.