Damage field ahead of a tensile crack in an elastic-plastic and viscoplastic material

摘要

This paper investigates the interaction between amacroscopic crack and microscopic damage in an elastic-plasticand viscoplastic material subjected to tensile in-plane loading.The aim is to predict the fracture conditions by accounting forvoid accumulation in the vicinity of the crack-tip. A power lawrelates the stress to the strain of the material. The damage, whichinvokes the growth and coalescence of microvoids, is confined toa small circular zone surrounding the crack-tip. At the onset ofcrack extension, the applied stress for small-scale and large-scaleyielding solutions is found to be proportional to a0-1/(n+1),where 2a0is the initial crack length and n is the strain hardeningexponent of the material. For small-scale yielding, the conditionsrequired for fatigue crack growth and steady-state creep aredetermined. In particular, the variations of the normalized cracklength with the number of loading cycles and the time requiredfor failure are shown for various strain hardening exponents,applied loading, and material damage parameters.