Energy expenditure and limitations in shock consolidation

Abstract

The energy dissipated by a shock wave as it traverses a powder is assessed. The various energy dissipation processes are analyzed: plastic deformation, interparticle friction, microkinetic energy, defect generation. An expression is developed for the energy requirement to shock consolidate a powder as a function of strength, size, porosity, and temperature, based on a prescribed interparticle melting layer. The corresponding pressures are calculated and it is shown that the activation of flaws occurs at tensile reflected pulses that are a decreasing fraction of the compressive pulse as the powder strength increases. These analytical results are compared to numerical solutions obtained by modeling the compaction of a discrete set of particles with an Eulerian finite element program.