Computaional Study of Powder Compaction Process with a View to Particles Designing

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This study deals with investigation into the behavior of powder materials from the state of "granular" through compact by means of computational scientific approach and thus to obtain useful information on particles designing ; we shall develop and establish "Particle Dynamics" or Distinct Element Method. We obtained the following results :1) By introducing for the particulate modeling the particle characteristics, such as particle size, size distribution and deformation characteristics, inter-particle ones, such as friction and elastic repulsive forces, we have developed an algorithm for simulation. We have thereby characterized some ceramic powder during compaction. We also evaluate the effect of inter-particle characteristics on apparent density, tap density and angle of repose.2) For ductile metallic powders, we have developed particulate model in 3-D with incorporating shape change in particle due to plastic defomiation. We have thus improved the relationship between pressure and density.3) We have obtained yield surface which are similar to those obtained by three-dimensional compaction and estimated by constitutive equations for powders.4) By incorporating the effect of magnetic field into the above algorithm, we have developed simulation program for compaction of magnetic powders in magnetic field with a view to optimizing the magnetic properties of compact magnet. We have thereby shown that isostatic compaction gives the best property followed by cross conipaction and then parallel comipaction.5) We have also developed algorithm for simulating the behavior of non-spherical particles, because the shape of the particles gives great influence on powder characteristics.For future study, the quantitative difference in pressure-density relationship between the simulation and experiment should be decreased and the effect of particle shape on powder behavior should further be investigated.