MESOSCOPIC MODEL OF CRACK BRANCHING

Dynamic crack propagation has been studied using a mesoscopic dissipat ive spring model. Results are in agreement with recent experiments by Sharon et al. [Phys. Rev. Lett. 74, 5096 (1995)] showing crack branchi ng and speed oscillation of the main crack beyond a critical speed. Si milar oscillations are seen in local kinetic and potential energies ne ar the propagating crack tip. These out-of-phase oscillations show tha t kinetic energy is directly transformed to potential energy. We also present evidence that branching is caused by a large crack boundary ve locity.