Representation and Probability Issues in the Simulation of Multi-Site Damage

The types of multi-site damage which are observed in fuselage skins preclude use of common simplifications employed in simulating crack growth. Interaction of cracks with each other and with structural features causes arbitrary growth patterns. Representation of a number of arbitrarily growing cracks in a finite element model is a problem which can be addressed with new codes built on a topological data structure and employing automatic remeshing. Examples of such codes applied to problems of interacting cracks, crack interaction with rivet holes, and cracking beneath a boron/epoxy patch are presented. A technique for incorporating probability methods into simulations of arbitrary crack growth is also presented and discussed via an example problem.