On the influence of microcantilever pre-crack geometries on the apparent fracture toughness of brittle materials

Focused ion beam machined microcantilevers are frequently used for fracture mechanics analysis of inhomogeneous solids at the micrometer scale. A finite element method study about the influence of the pre-crack geometry on the apparent fracture toughness is provided. We discuss the influence of material bridges and the effect of rounded pre-crack corners when two dimensional models are employed to evaluate the fracture toughness. We conclude with a guideline for introducing an optimized pre-crack.