Generalized model of an elastoplastic cracked body

We propose a generalized model of an elastoplastic cracked body which takes into account not only the zone of plastic yield but-also the prefracture zone (the final descending section of the complete tensile stress-strain diagram) and formulate a strain criterion of limiting equilibrium based on the use of the following characteristics of the material: the maximum level of stresses in the plastic zone sigma(0), the critical crack tip opening displacement delta(c), and the critical sizes of the prefracture zone d(s) and the zone of plastic yield d(nc). The parameters sigma(0) and delta(c) are measured experimentally, while d(s) and d(nc) are determined from the criterional equations. We also consider the case of a brittle body (the zone of plastic yield is absent) and present the characteristics of crack-growth resistance of D16T alloy found within the framework of the proposed model.