Critical conditions for failure; stress levels, length scales, time scales~

There is a range of thresholds for the response of condensed matter under loading in compression, from the yield~point to that at which the bond strength is overcome and warm dense matter is formed. Yield stress shows a correlation~between the length scale swept by the rise of the pulse and the defect distribution within the target for a range of~materials. Strain rate is also a useful term that reflects the~evolution of the stress state within a target but must also be defined for a volume element containing a particular defect~distribution to reflect continuum conditions acting within and thus applies to a defined length scale within a target. Examples are shown using shock pulses to spall metal targets. Different stacking shows differing behaviour yet in each case momentum is conserved. This~overview of behaviour suggests concepts borrowed from rate-independent plasticity may be viewed in a different~manner and accompanying behaviours such as brittle-ductile transition may be reviewed when explaining a range of~dynamic failure modes under load for materials and structures. ~