Zniszczenie w zakresie lepkoplastycznym

Determinatin of structure resistance to fracture generally takes place in two stages: initiation of cracks and their propagation. In the first part of the paper we develop the mechanical theory of fracture, based upon the notion of effective stress. Using the thermodynamics of irreversible processes, a continuous variable of fracture-deformation coupling. This coupling enables to develop indirect measurements of creep and fatigue fracture, and hence to identify the models of evolution. In the second part we present a generalization of the notion of the rate of energy release, well-known in the linear fracture mechanics, to problems of nonlinear viscoplasticity. Also in this case thermodynamical considerations lead to models of a crack growth due to fatigue and fracture, the interaction being taken into account.