Investigation Into Field Structure at Mode Ⅲ Dynamically Propagating Crack Tip in Elastic-Visco-Plastic Materials

An elastic-viscoplastic mechanics model was adopted to investigate asymptotically the mode Ⅲ dynamically propagating crack tip field in elastic-viscoplastic materials.The stress and strain fields at crack tip possess the same powe-rlaw singularity under linear-hardening condition.And the singularity exponent is uniquely determined by the viscosity coefficient of the material.Numerical calculation results indicate that the motion parameter of crack propagating speed has little effect itself on zone structure at crack tip.The hardening coefficient dominates the structure of crack-tip field but the secondary plastic zone has little influence on the field.The viscosity of the material dominates the strength of stress and strain fields at crack tip while it does have certain influence on crack-tip field structure.The dynamic crack-tip field degenerates into the relevant quasistatic solution when the crack moving speed is zero.And the corresponding perfectly-plastic solution is recovered from the linear-hardening solution when the hardening coefficient becomes zero.