THERMODYNAMIC MODEL OF THE COMPACTION OF POWDER MATERIALS BY SHOCK-WAVES

For powder materials a model is proposed to predict the mean temperatu re behind the shock wave, the ratio between the increase of thermal en ergy and increase of total internal energy, as well as the mean final temperature after release of adiabatic pressure. Further, the change o f pressure, specific volume, and the internal energy behind the shock wave are calculated together with the shock-wave velocity. All these v ariables are supposed to depend exclusively on flyer plate velocity, i nitial powder density, and initial powder temperature. The ratio betwe en the increase of thermal energy and increase of total internal energ y decreases rapidly upon decreasing initial powder density, resulting in a higher shock temperature and a lower shock pressure; therefore, a lower initial powder density results in a better bonding between the particles and fewer cracks after pressure release. Calculations are ca rried out for copper and agree fairly well with experiments.