A cohesive plastic/damage-zone model for ductile crack analysis Original Research Article

A cohesive plastic/damage-zone model of the Dugdale-Barenblatt type (G.I. Barenblatt, Adv. Appl. Mech. 7 (1962) 55–129; D.S. Dugdale, J. Mech. Phys. Solids 8 (1960) 100–104) is presented for analyzing crack growth in ductile materials with damage evolution. A semi-infinite Mode I crack in plane stress or plane strain is considered. The damage is assumed to be present in form of dispersed microvoids which are localized into a narrow strip ahead of the crack-tip. A simple damage model of the Gurson model type (A.L. Gurson, J. Eng. Mater. Technol. 99 (1977) 2–15; V. Tvergaard, Advances in Applied Mechanics, Vol. 27, Academic Press, 1990, pp. 83–151) is developed for uniaxial tension to describe the macroscopic properties of the cohesive plastic/damage-zone. Under small-scale yielding and small-scale damage conditions, a system of nonlinear integral equations for the plastic strain and the length of the cohesive plastic/damage-zone is derived. Numerical results are presented and discussed to reveal the effect of damage evolution on the ductile crack growth.