A three-dimensional crack growth simulator with displacement discontinuity method

摘要

This paper first outlines the theory of a well established three dimensional boundary element method: displacement discontinuity method (DDM) and proposes to use a crack growth criterion based on maximum normal or shear stress for a three dimensional crack growth simulator, FRACOD~(3D). Triangular elements are used in the simulator code. A numerical scheme is used to overcome a difficulty associated with the evaluation of the basic solution for DDM in some special situations and another numerical scheme is used to calculate the stresses on the boundary elements where the stresses obtained from the normal DDM scheme have large errors. The crack growth is implemented incrementally in that new front elements are introduced at the crack front; thus no need to re-mesh the old part of the cracks. The effects of neighbouring front elements are taken into account in implementation of the crack growth to overcome severer twisting of the new front elements generated from the growth. The numerical results from FRACOD~(3D) of two simple examples agree very well with analytical solutions, and propagation configuration of a circular disc crack in an infinite body under shear is close to that observed in an experiment in literature under similar loading condition.