Energy dissipation in dynamic fracture of brittle materials

Dynamic crack growth in a plane strain strip is analysed using a cohesive s urface fracture framework where the continuum is characterized by two const itutive relations: a material constitutive law that relates stress and stra in, and a relation between the tractions and displacement jumps across a sp ecified set of cohesive surfaces. The material constitutive relation is tha t of an isotropic hyperelastic solid. The cohesive surface constitutive rel ation introduces a characteristic length into the formulation. The resistan ce to crack initiation and the crack speed history are predicted without in voking any additional failure criterion. Finite-strain transient analyses a re carried out, with a focus on the relation between the increase in fractu re energy with crack speed and the increase in surface area due to crack br anching. The numerical results show that, even with a fixed work of separat ion per unit area, there is a substantial increase in fracture energy with increasing crack speed. This arises from an increase in fracture surface ar ea due to crack branching. The computational results are in good agreement with experimental observations in Sharon et al [1].