Simulation of mode I crack growth in polymers by crazing

Crazing in amorphous polymers under mode I loading conditions is simulated using the concept of embedded cohesive surfaces with a recently proposed model. The dependence of the predicted crack growth resistance on the crazing material parameters is studied. In general, for constant loading rate, a lower fracture toughness is predicted for shorter craze lengths. However, since the widening of the craze is of a viscoplastic nature, this trend can be reversed for increasing loading rate. The parameter variations indicate that the perfectly plastic Dugdale cohesive zone model is not applicable to crazing. Mesh sensitivity with respect to length and orientation of the cohesive surface elements is also studied. Convergence of crack growth resistance and crack path predictions can only be expected for very fine, randomly oriented meshes.