ABSTRACT

Abstract The efficient numerical simulation of arbitrary, non-planar, discrete crack growth in three-dimensional solids requires a system capable of representing the changing model geometry as the crack propagates without limiting the crack growth to predefined paths. F R A N C 3 D , a graphical, menu-driven, computer-aided design tool provides this framework through the use of a topology-based data structure and a hierarchical level of models . The underlying topological framework of F R A N C 3 D is described with special emphasis on the requirements for simulating three-dimensional crack growth. Then F R A N C 3D is applied to the numerical simulation of the propagation of a cohesive crack in a short-rod concrete specimen and hydraulic fracture propagation from an uncased wellbore, including both a deviated and a vertical borehole. The ability of the system to model non­ uniform and non-planar crack growth in 3D structures is clearly demonstrated; this includes the ability to model both cohesive fracture propagation and linear-elastic fracture propagation coupled with fluid flow. Keywords : Topology, 3D-Crack Growth, Cohesive Crack, Hydraulic Fracture

1 Introduction

Fracture mechanics has progressed significantly since Griffith's initial work (Griffith, 1921). Linear elastic (LEFM) , non-linear (NFM) , and other fracture mechanics theories are well established. Most efforts have been directed towards the study of Mode I crack growth, but mixed M o d e I and II problems are understood quite well , for 2D problems at least (see: Whit taker et al., 1992; Kanninen and Popelar, 1985). However , 3D problems, such as general mixed Mode I, II and III fracture (Hodgdon and Sethna, 1993; Leblond, 1993), cracks in or across interfaces (Lee et al, 1988), multiple crack interaction (Huang and Karihaloo, 1993), coalescence and branching have received more attention recently.