Asymptotic fields for dynamic crack growth in pressure-sensitive elastic-plastic materials

Asymptotic analyses for dynamic propagation of mode I planar cracks in pressure-sensitive elastic plastic materials have been carried out. The material model adopted is based on the Drucker Prager yield surface obeying the associate flow rule with linear isotropic hardening. The asymptotic solution is assumed to be of the variable-separable form with a power singularity in the radial coordinate from the crack tip. Attention is focused on the inertia effect on some features of the asymptotic solutions. It is found that for plane-strain cases, the range of pressure sensitivity can be expanded by increasing the crack speed due to a delay in the occurrence of a hydrostatic stress state ahead of the crack tip. An increase in crack speed produces a corresponding change in the characteristics of the governing equations because of a tendency to produce strain and stress 'jumps'. Material and loading mode-dependent speed limits have also been studied under plane-strain and plane-stress conditions. In addition, numerical results are presented for the strength of singularity, the angular distributions of stresses and velocities, and the crack-tip constraint.