Shock-induced ultrafast SHS reactions

Mixtures of reactive powders can be ignited in several ways. These systems have high activation energies and significant preheating is required. Traditionally conduction has been considered as the main form of preheating and self-propagating velocities of the order of a few millimeters to a few centimeters per second are typical. Ultrafast modes of propagation are observed through the application of initial pressure and particle velocity to the system, which cause significant heating by compression. The model also includes the compaction of porous preforms. The constitutive relations have been amended to accommodate yielding and dilatation. Dissipative forces contribute to preheating and replace thermal conduction as the primary mode of activation. The model is pseudo-homogeneous insofar as no distinction is made between physical properties of different species, as well as differences in their response to shock waves (e.g., local differences in particle velocities).