A Fracture Criterion of "Barenblatt" Type for an Intersonic Shear Crack.

Steady-state intersonic propagation of a shear crack is considered, with the admission of cohesion across the crack faces. The asymptotic limit of "small-scale cohesion", which occurs when the magnitude of the cohesive stress far exceeds that of the applied stress, is developed explicitly, to obtain a criterion of "Barenblatt" type. The application of this criterion requires only the calculation of the "applied" stress in- tensity coefficient with cohesion disregarded; an equation of motion follows by equating this coefficient to a "modulus of cohesion" which depends on the cohesive model that is employed. An explicit formula for the "modulus of cohesion" is given for the special case of a cohesive zone of Dugdale type. [ABSTRACT FROM AUTHOR]