supersonic region, two stress shocks radiate from the crack tip, corresponding to shear and dilatation wave radiation,

Here the length scales refer to the bonding layer thickness and the materials intrinsic length that governs energy dissipation during failure; whereas the time scales refer to the effects of material strain rate dependence, material failure speed, and wave propagation properties. A parameter Rs, expressed as the ratio of material shear strength and the applied stress that is calculated from the remote imposed displacement boundary condition, is proposed to scale crack speed. Intersonic propagation occurs when Rs is greater than a threshold value. The numerical computations are compared with experiments (Rosakis et al., 1999; Rosakis, 2002) and the theoretical solution [Philos. Mag., A, in press], which demonstrates the trend that crack propagation is unstable in the open speed interval between cs and jvcsModeling and simulation of intersonic crack growt