A Cohesive Approach to Thin-shell Fracture and Fragmentation

We develop a finite-element method for the simulation of dynamic shell fracture and fragmentation based on cohesive models of fracture. We assume the shells to be thin and to obey the Kirchhoff-Love theory. The shell is spatially discretized by means of subdivision shell elements. Fracture is allowed only along element edges and is assumed to be governed by a cohesive law. When coupled to the shell kinematics, the cohesive model accounts both for in-plane or tearing, shearing, and bending or hinge modes of fracture. In order to follow the propagation and branching of cracks, subdivision shell elements are pre-fractured ab initio. Prior to crack nucleation, crack opening is constrained by means of a penalty method in implicit calculations, or by a projection or displacement averaging method in explicit calculations. The good performance of the method is demonstrated through the simulation of petalling failure experiments in aluminum plates.