Modeling Of Crack Propagation In Thin-Walled Structures

Abstract

A cohesive interface element is presented for the finite element analysis of crack
growth in thin specimens. In this work, the traditional cohesive interface model is extended to
handle cracks in the context of three-dimensional shell elements. In addition to the tractiondisplacement
law, a bending moment-rotation relation is included to transmit the moment and
describe the initiation and propagation of cracks growing through the thickness of the shell
elements. Since crack initiation and evolution are a natural outcome of the cohesive zone
model without the need of any ad-hoc fracture criterion, this model results in automatic
prediction of fracture. In particular, this paper will focus on cases involving Mode I/III
fracture and bending, typical of complex cases existing in industrial applications in which
thin-walled structures are subjected to extreme loading conditions (e.g., crashworthiness
analysis). Finally, we will discuss how the three-dimensional effects near the crack front may
affect the determination of the cohesive parameters to be used with this model.