Asymptotic field of mode II dynamic growing crack in visco-elastic material

A mechanical model of visco-elastic material is established in order to investigate viscous effect in dynamic growing crack-tip field of mode II. It is shown that in stable creep growing phase, elastic deformation and viscous deformation are equally dominant in the near-tip field, the stress and strain have the same signularity, namely (σε) ∝r−1(n−1). The asymptotic solutions of separatied variables of stress, stain and displacement in crack-tip field are obtained by asymptotic analysis, and the results of numerical value of stress and strain in crack-tip field are obtained by shooting method. Through numerical calculation, it is shown that the near-tip fields are mainly governed by the creep exponentn and Mach numberM. By the asymptotic analysis to the crack-tip field, the fracture criterion of mode II dynamic growing crack of visco-elastic materials is put forward from the point of view of strain.