Path differences between quasistatic and fatigue cracks in anisotropic media

The propagation path of quasistatic cracks under monotonic loading is known to be strongly influenced by the anisotropy of the fracture energy in crystalline solids or engineered materials with a regular microstructure. Such cracks generally follow directions close to minima of the fracture energy. Here we demonstrate both experimentally and computationally that fatigue cracks under cyclic loading follow dramatically different paths that are predominantly dictated by the symmetry of the loading with the microstructure playing a negligible or subdominant role.