Determination of the initial direction of cracks growth at the moment of movement

A technique for determining the initial direction of the growth of a straight crack in a plate of elastic material with a load, applied at the boundaries of the plate in the plane strain conditions, is considered. In the paper analytical representations for the stress tensor components are given. The formulation of the problem and the sequence of steps for finding the value of the angle, at which subcritical crack growth begins, are described. The obtained theoretical dependences by definition of the characteristics of the limiting state of the construction allow making a motivated choice of geometric parameters with the strength properties of the material.