Compaction of Cohesive Powders

The ner a powder, the more its behaviour is dominated by cohesion. This is the reason why ne powders in the submicrometer range are highly porous. The stress that is needed to reduce the porosity by a de-sired amount is shown to be different in quasi-static and in shock compaction. The product of (consolidation stress)(compactible pore volume)1= turns out to be constant for a powder of rigid, round particles with an exponent 1= 2. How this constitutive law is modied in the case of shock compaction due to inertia effects, is derived analytically. Results of Contact Dynamics simulations and experiments are reviewed.