Shear-driven damage of ductile metals induced by indentation load

Although indentation does not induce apparent cracking in ductile materials, degradation of elastic stiffness of ductile metals has been found in micro-/macro- indentation tests. After comparing the predicted degradation by extended damaged-plasticity models with that measured by experimental testing, it is found that the softening caused by distortion of existing voids is inadequate to cause the notable degradation of elasticity. It is suggested that an independent damage-nucleation mechanism arising from shear deformation may exist. Although attractive in practical applications for its non-destructive nature, the damage-based indentation technique for estimating the fracture properties of ductile materials needs further investigation.