Compaction and elastic unloading of nanopowders in terms of granular dynamics

The behavior of nanopowders is simulated by a granular dynamics method. The elastic interaction of individual particles is described in terms of the rod model of contact, which is the generalization of the classical Hertz law and can be applied in the case of relatively strong particle deformation. The processes of uniaxial compression/tension in a rigid matrix are analyzed. The calculated data on the elastic properties of model systems are compared to the experimental data obtained for oxide nanopowders. The simulation of unloading (tension) makes it possible to separate the plastic irreversible part and the elastic part in the total strain of a powder body. The effect of the particle size on the elastic properties and the final density of the powder compact is studied, and the residual lateral stresses in powder compacts after the removal of an axial load and the maximum oxide nanopowder densities reached at high pressures are estimated.