Crack driving forces for short cracks: The effect of work hardening

The effect of hardening on the crack tip deformation of short cracks is investigated by FEM analysis. The analyses of the results show that the commonly used Shih-Hutchinson and Dowling equations for the calculation of the J integral are very good approximations for small and large scale yielding conditions. This method is developed for hardening materials and provides a rough approximation for ideal-plastic or even for softening materials, as long as full scale yielding does not take place. However, in the case of full scale yielding these equations do not provide a satisfying estimation of the J integral or crack tip deformation for non-hardening or softening materials, due to a strong dependency on the plastic correction factor. The impact of this phenomenon for nanocrystalline metals or metallic glasses will be pointed out shortly.