Crack Tip Flipping Under Mode I/III Tearing

Crack tip flipping, where the fracture surface alternates from side to side in 45° shear bands, seems to be an overlooked propagation mode in Mode I sheet tearing often disregarded as  “transitional” or tied to randomness in the material. In fact, such observations rarely make it to the literature. However, crack tip flipping is a true propagation mode, but unlike those already established: i) it never settles in a steady-state as the near tip stress/strain field continuously change, and ii) the mechanism governing failure evolves behind the leading crack tip. Recent research has revealed new insight into this intriguing behavior of a crack propagating by the void nucleation and growth mechanism, and the work presented compiles both published and unpublished experimental and numerical findings. E.g. in a recent attempt to gain control of the flipping crack a slight Mode III was imposed with interesting results.