Cohesive crack model with rate-dependence and viscoelasticity

Although fracture can often be considered as time-dependent, in many situations the time dependence of fracture must be taken into account. This case holds true for both dynamic fracture and for static fracture under long-time loading. The time dependence of fracture has in the past been studied chiefly for the materials in which the fracture process zone is small relative to the structure size. This cannot be assumed for quasibrittle materials with coarse heterogeneous microstructure. In these materials, the time-dependent generalization must be based on models that take the existence of a large fracture process zone into account.