Effect of plastic deformation on the elastic stress field near a crack tip under small-scale yielding conditions: An extended Irwin's model.

• An extended Irwin's model is developed with introduction of the Plasticity-affected zone. • The contradiction between classic Irwin's model and the shielding effect of crack-tip plastic zone is resolved in the proposed model. • The effect of crack-tip plastic zone on the crack-tip elastic stress field is quantified. • Crack problems with T-stress can be analyzed by the extended Irwin's model. The effective stress intensity factor derived from Irwin's model is greater than the linear elastic counterpart. This is in contradiction to the shielding effect of crack-tip plastic zone. Besides, the classic Irwin's model underestimates the size of the crack-tip plastic zone compared with Dugdale's model and FE analysis. In this paper, an extended Irwin's model for elastic perfectly-plastic material under small-scale yielding conditions is developed through imposing static equivalence between the plasticity-affected stress field and linear elastic stress field in the plasticity-affected zone. The extended Irwin's model is capable of quantifying the effect of the crack-tip plastic zone on the crack-tip elastic stress field. It reduces to the classic Irwin's model in the limiting case. This new version of Irwin's model provides new insights in elucidating the effect of the crack-tip plastic zone on fracture behavior. [ABSTRACT FROM AUTHOR]