Hot spots are localized regions of high temperature. They can result from a variety of mechanisms, such as plastic work, frictional heating or pore collapse. Hot spots can however be studied numerically by applying continuum mechanics models to a small sample of the material. These highly resolved computations are known as micro-mechanical simulations. A granular explosive has an extra degree of freedom associated with porosity and can be used to represent a damaged material.
Stress concentrations arise at the contact between grains.
When the peak stress exceeds the yield stress, the grain deforms plastically. The computations show hot spots arising from localized plastic work and from frictional heating when one grain slides past its neighbors. This is a key incredient needed to develop a subgrid burn model that is valid over a wider enough range of conditions to predict weak initiation of a high explosive. Group T-14 homepage .