Modeling of stochastic properties of fast cracks in quasi-brittle materials

In this contribution, a statistically based approach for investigation of damage-fracture transition in brittle material is proposed. Based on this approach the process of crack tip instability in PMMA is theoretically investigated. It is show that the self-similar solutions of the kinetic constitutive equations describe the existence of a specific type of the developed stage of damage, which is characterized by the explosion-like kinetics of the microcrack growth on the spectrum of spatial scales. From the results of the self-similar solution analysis it is appeared that the steady-state––branching transition occurs when the microcrack ensemble has no enough time for generation of the self-similar pattern and its evolution. eoretical results are supported by the numerical simulation of crack dynamics in PMMA specimen.