Materials’ Physics in Extremes: Akrology

An understanding of the behavior of materials in mechanical extremes has become a pressing need in order to exploit new environments. Any impulse consists of a cascade of deformation mechanisms starting with ultrafast and concluding with slower ones, yet these have not been suitably defined over the past years. This requirement has prompted the design of new experimental platforms and diagnostics and an increase in modern computer power. However, this effort has removed necessary focus on the operating suite of deformation mechanisms activated in loaded materials. This article reviews the material response and attempts to order physical pathways according to the length and time scales they operate within. A dimensionless constant is introduced to scale the contributions of component pathways by quantifying their completion with respect to the loading impulse applied. This concept is extended to suggest a new framework to describe the response to arbitrary insult and to show the relevance of particular techniques to component parts of the problem. The application of a step impulse via shock loading is shown to be the primary derivation experiment to address these needs and map components of the response.