Crack bifurcation behavior of coarse-grained copper under cyclic torsion combined with axial static loading

Abstract

Because the growth behaviors of fatigue cracks are crucial for the safe assessment of structural components, the crack propagation behaviors of coarse-grained copper (CG Cu) subjected to cyclic torsion combined with different axial static stresses were studied. The crack bifurcation behavior is related to the strain amplitude applied. When the strain amplitude is lower, both the type and the magnitude of axial stress have no significant effect on the direction in which the primary crack branches, which is mainly determined by the position of the maximum normal plane. However, when the strain amplitude is higher, the bifurcated crack deviates visibly from the maximum normal plane, which can be attributed to the high degree of plastic deformation and microcracks caused by slip bands along longitudinal direction.