Phenomenological aspects of viscoelastic crack propagation

The strain rate dependence on dynamic crack propagation in viscoelastic solids was experimentally verified for PMMA by the velocity gauge method and fracture surface observation. It was found that the dependence was mainly due to the viscous term effect, and this was supported by the observation of deviation of the stress-strain curve from an elastic case. The elastic brittle crack propagation can be realized only in the high-strain rate case for PMMA.