Effect of strain dependent cohesive zone model on predictions of crack growth resistance

Crack growth in an elastic-plastic solid is studied by a computational model, in which a cohesive zone model is used to characterize the fracture process. The separation work per unit area and the peak stress required for separation are the basic parameters in the cohesive zone model, but also an effect of plastic straining, reducing the peak stress for separation, is incorporated here. This additional effect represents acceleration of the void growth process and nucleation of more voids, resulting from intense plastic straining in the immediate vicinity of the crack tip. The analyses are carried out for conditions of small-scale yielding under plane strain, with the mode I stress intensity factors specified at the loading parameter. Also the effect of a T-stress on crack growth resistance is investigated.