ON THE APPLICATION OF THE STRAIN-ENERGY DENSITY THEORY IN PREDICTING CRACK INITIATION AND ANGLE OF GROWTH

Until recently, the one-parameter singular expression for stresses near a crack-tip was widely thought to be sufficiently accurate for any geometry and loading conditions. This view has been fast changing due to the growing evidence that the inclusion of higher order terms can significantly affect the solution, particularly under certain biaxial loading conditions. In this context, the present paper examines the strain energy density criterion for fracture, and the consequences of the assumption of a 1/r energy singularity in the formulation on its application. It is found that this assumption imposes a rather severe restriction on the region for which the criterion is applicable, and that its application on an arbitrarily selected 'small' distance from the crack-tip can lead to erroneous results.