Numerical analysis of multi-scale mechanical theory of densified powder compaction

Abstract

Multi-scale mechanical theory of powder compacting is the foundation for improving the quality of the product made by powder metallurgy. Aimed at powder compacting process, a 2D numerical model of the single-direction granular compacting system is established by the discrete element method. Using this DEM numerical model, the stress–strain responses, directional distributions of velocity vector and distributions of force chains in the compacting stage are studied. Research results show that powder granules successively go through the phase transformation processes of flow state, quasi-static and jamming state in the compacting process. Clearly, it is noted that velocity direction distribution of powder granule is closely related to the granule flow state, and dilatancy behavior of powder granule is a main reason for influencing the velocity direction distribution of powder granules under the quasi-static. The contact normal force, contact tangential force and contact force all comply with a power law forms, and the strength of force chains between powder granules increases with increased inter-granule friction coefficient.