Crack path predictions and experiments in plane structures considering anisotropic properties and material interfaces

Abstract

In many engineering applications special requirements are directed to a material's fracture behavior
and the prediction of crack paths. Especially if the material exhibits anisotropic elastic properties or fracture
toughnesses, e.g. in textured or composite materials, the simulation of crack paths is challenging. Here, the
application of path independent interaction integrals (I-integrals), J-, L- and M-integrals is beneficial for an
accurate crack tip loading analysis.
Numerical tools for the calculation of loading quantities using these path-invariant integrals are implemented
into the commercial finite element (FE)-code ABAQUS. Global approaches of the integrals are convenient
considering crack tips approaching other crack faces, internal boundaries or material interfaces. Curved crack
faces require special treatment with respect to integration contours. Numerical crack paths are predicted based
on FE calculations of the boundary value problem in connection with an intelligent adaptive re-meshing
algorithm. Considering fracture toughness anisotropy and accounting for inelastic effects due to small plastic
zones in the crack tip region, the numerically predicted crack paths of different types of specimens with material interfaces and internal boundaries are compared to subcritically grown paths obtained from experiments.