2D-simulation of Nanopowder High-Speed Compaction

The paper concerns the nanopowder high-speed, 104 – 109 s–1, compaction processes modelling by a two-dimensional granular dynamics method. Nanoparticles interaction, in addition to known contact laws, included dispersive attraction, the formation of a strong interparticle bonding (powder agglomeration) as well as the forces caused by viscous stresses in the contact region. For different densification rates, the "pressure vs. density" curves (densification curves) were calculated. Relaxation of the stresses after the compression stage was analysed as well. The densification curves analysis allowed us to suggest the dependence of compaction pressure as a function of strain rate. It was found that in contrast to the plastic flow of metals, where the yield strength is proportional to the logarithm of the strain rate, the power-law dependence of applied pressure on the strain rate as was established for the modelled nanosized powders.