Shear localization: A historical overview

This review presents a historical approach to the development of understanding of the shear localization phenomenon in materials, concentrating particularly on impact. Deformation localization under these conditions is widely referred to as adiabatic shear banding as the timescales are such that the distances heat can diffuse are small. Dimensional analysis shows that the phenomenon is ultimately intractable to linear algebraic analysis, as it is a coupled mechanical/thermal problem. However, various linear analyses from the literature are discussed along with their limitations as they shed light on the influence of various material properties. The aim of gaining understanding is to be able to engineer materials with the required localization (and hence fracture) characteristics. The most advanced analyses show that shear band widths and spacings are determined by optimizing the diffusion of heat and inertia. Because inertia is involved, the phenomenon cannot be understood simply as a materials property: geometry and structure must play a role.