Computational Aspects of Three-Dimensional Crack Growth Simulations

An important task in mixed-mode fracture analysis and prediction is the simulation of crack growth under mixed-mode conditions. To complete such a task, one must have (a) a computer code capable of handling the kinematics of general crack growth and determining the stress and deformation states during crack growth, and (b) a fracture criterion that can properly predict the onset and direction of crack growth. A current challenge is the simulation of mixed-mode crack growth under three-dimensional (3D) conditions, such as the growth of surface cracks, corner cracks, embedded cracks, and cracks with a curved crack surface and/or a curved crack front. This paper focuses on item (a) in the above discussion and describes the computational aspects of a simulation procedure, which can be used together with a given fracture criterion to simulate crack growth. For illustration purposes, a CTOD fracture criterion (e.g. [11]) will be used when needed. The associated algorithms for simulating arbitrary 3D crack growth under general loading conditions have been developed and successfully implemented by the authors in a custom, finite element based, crack growth analysis and simulation code—CRACK3D. In particular, this paper will present strategies for automatic re-meshing of regions around growing crack fronts in a 3D body, and will discuss verification examples.