Structural geometry, fracture process zone and fracture energy

This paper is focused on the influence of structural size and geometry on the size and shape of the fracture process zone FPZ), and consequently on the progress of the fracture energy dissipated within the FPZ during the fracture process in structures made of quasi-brittle materials. The effect of structural geometry on its fracture behaviour is described here by two-parameter fracture mechanics, in particular by the constraint ofstress near the equivalent elastic crack tip. The local fracture energy concept is evolved. Attention is paid to finding the intermediate stage of the fracture when there is no direct influence of the specimen boundary on the FPZ size and shape (and consequently the value of fracture energy dissipated within it). The research was conducted by means of numerical simulations of fracture tests in two testing configurations with different constraint conditions. The features of the distribution of local/averaged fracture energy along the specimen ligament are discussed. Based on the courses of these functions, it is shown that the size and shape of the FPZ are strongly influenced by structural size and geometry.