A tactic of two-side estimates of limiting bending loads for plates with contact cracks

The problem of plate bending, weakened by rectilinear through crack, taking into account the contact of defect faces is considered. A detailed analysis of the analytical solution obtained previously by the classical theories of the plates within the framework of a model of crack closure along the line is performed. According to the data for intensity factors of forces and moments, the distribution of stress intensity factor across the plate thickness has been restored. We pay particular attention to the problem of determining the value of the fracture bending load. Process of propagation of the crack with non-uniformly stressed front in conditions of bending consists of two stages: irregular over its thickness consistent growth of the crack when load reaches its lower limiting value and unstable propagation of the crack when load reaches its upper limiting value. Analytical estimates of such limiting values are made using of the force and energy criteria of linear mechanics of fracture. The authors’ experience with the determine the limiting bending loads for some contact cracks systems in infinite and semi-infinite plate sis illustrated too.