Abstract

R-curves caused by crack face interactions are important for the strength assessment of components with small cracks. Whereas an influence of the initial crack length on the R-curve is well understood on the basis of fracture mechanics, it will be shown here that also the type of the crack affects the crack growth resistance. For a given crack-bridging relation it can be shown that 3-dimensional cracks as circular internal cracks and semi-circular surface cracks must exhibit a lower R-curve than obtainable from 2-dimensional edge cracks.