Comparative analysis of extrinsic and intrinsic cohesive models of dynamic fracture

A comparative analysis of intrinsic and extrinsic cohesive models has been performed for the case of spontaneous and steady-state dynamic crack propagation. Spontaneous crack propagation was simulated using a spectral form of the elastodynamic boundary integral equation, while steady-state solutions were obtained by numerically integrating the governing Cauchy singular integral equation. Spontaneous crack propagation results showed that intrinsic models are less numerically stable than the extrinsic ones. Under steady-state propagation conditions, some intrinsic cohesive models lead to unrealistic results as the crack opening velocity becomes negative at the cohesive zone tip. By imposing a positive crack opening acceleration at the cohesive zone tip, the envelope of the required minimum initial strength has been calculated.