A comparison of discrete element model predictions to observations of metal powder consolidation

A number of substantial differences were observed in direct comparisons between DEM simulation results and experimental measurements of metal powder consolidation behavior. The Poisson's ratio of the DEM powder compact differed dramatically from that obtained from experimental measurements. The trend with relative density was opposite to experimental measurements for Ti-14Al-21Nb and an analytical model that fits a wide variety of other materials. The DEM network model also predicted macroscopic flow stresses in uniaxial compression far in excess of those measured experimentally and the evolution of interparticle contacts (both number and size of contacts) during HIP that differed dramatically from experimental measurements. The differences between the simulation and experimentally observed results were attributed to the omission of significant consolidation mechanisms from the simulation package. The complex nature of the DEM network model and solution algorithms also leaves the possibility that numerical problems could have caused some of the differences, thus underscoring the need to apply the DEM approach with caution. Ti-6Al-4V was also examined.