MODELING OF 3-D MIXED-MODE FRACTURES NEAR PLANAR BIMATERIAL INTERFACES USING SURFACE INTEGRALS

Mixed-mode fractures of arbitrary orientation with respect to a planar bimaterial interface have been effectively modelled using a surface i ntegral approach. By requiring only that the surface of the fracture b e discretized, the surface integral method circumvents the practical d ifficulties associated with having to mesh the interacting dual singul arities in stress along the three-dimensional (3-D) crack front and at the interface. The key elements of this numerical capability are disc ussed in detail. These include: the derivation of the fundamental solu tions for a generalized fracture event near a planar bimaterial interf ace, formulation of the governing integral equation including its deco mposition into singular and non-singular terms, development of analyti cal and numerical techniques for performing the singular integrations, and efficient numerical integration of the non-singular terms using n on-dimensionalized surface approximations of the dipole solutions. The problem of a pressurized planar crack near a bimaterial interface was used to assess convergence. The effect of material contrast and crack shape on tendencies for crack growth were also examined.