A material force analysis of crack growth in a viscoelastic strip

The material force method for inelastic fracture is applied to study steady-state crack growth in a thin viscoelastic strip. The method calculates the work rate of dissipation from a balance of energy momentum that explicitly accounts for the effects of viscoelastic behavior. In a finite element framework, the method provides a tool to visualize the viscous dissipation zone. Simulations of crack growth using inter-element cohesive surfaces was performed for strips of various sizes. The same driving force was applied to each strip. Results show that the finite width of the strip constrains the development of the viscous dissipation zone. There is a critical size of the strip relative to the viscoelastic length scale, calculated by the crack speed and characteristic relaxation time, below which the crack speed exhibits a dependence on geometry.