Combined Loading Pattern of a Spatial Crack.

The paper deals with the investigation of the state of stress near spatial crack of arbitrary contour and the direction of propagation of such a crack under combined loading pattern. The author takes up the problem of determination of the critical value of loading under which the cracks start to propagate. The crack propagation sets in at the moment when the factor of strain energy aquires a critical value. To determine the value of the strain energy factor it is necessary to know the values of stress intensity factors for the given crack. The stress intensity factors are calculated by the boundary element method.