Nonlinear and structural aspects of transitions from damage to fracture in composites and structures

Statistical theory of defect evolution allows us to obtain nonlinear kinetic equations for tensor parameter of microcrack density. The laws of spatial damage localization on various structural levels are defined by the nonlinearity of the microcrack accumulation in the condition of intensive interaction of the defects. This leads to the multiscale generation of failure centers. The relation between typical nonlinearity of damage kinetics and spatial failure localization is the theoretical background for the explanation of experimental results and numerical simulation of fracture in heterogeneous materials. Topological features of fracture development were investigated numerically using percolation model of failure cluster growth.