ELASTODYNAMIC EFFECTS ON CRACK ARREST.

The first part of the paper is concerned with the elastodynamic stress field in the vicinity of a rapidly propagating crack tip. Elastodynamic stress intensity factors and their role in the fracture criterion of the balance of rates of energies are discussed. The remainder of the paper deals with the near-tip stress field for a sudden discontinuous change of the speed of a rapidly propagating crack tip, including the case that the crack tip is suddenly arrested. Analytical expressions are derived for the elastodynamic stress intensity factor, for the case that the crack-tip speed instantaneously changes from c//1 to c//2, where c//2 less than c//1. Arrest, or continued propagation of a crack tip at a reduced speed is investigated on the basis of the fracture criterion of the balance of rates of energies.