Investigation of the flow and force chain characteristics of metal powder in high-velocity compaction based on a discrete element method

The flow and force chain characteristics of metal powder in high-velocity compaction are not fundamentally understood because of the complexities and discreteness of these particle systems. A 2D discrete element model of a metal powder subjected to uniaxial compaction is developed. The flow state of particles, the force chain distribution, and the influence of the main model parameters on the force chains are investigated. Results indicate a collisional particle flow stage at the beginning of compaction. Then, the flow state of particles can rapidly be classified as a dense particle flow. In addition, the contact force distribution for the collisional particle flow follows an exponential law, which is significantly different from that for dense particle flow. The probability distribution of contact forces changes as a power function in the dense particle flow. The force chains initially deviate in the y-axis direction and then in the x-axis direction with increasing friction coefficient, and the distribution and load-carrying rates of the weak force chains decrease with increasing friction coefficient. Moreover, the force chains deflect in the direction of the x-axis with increasing the particle diameter, and the distribution rate and load-carrying rate of the weak force chains decrease with increasing particle diameter. These changes in the direction of the force chains are similar to the density changes in the compacted blank part parts. The distribution rate and the load-carrying rate of the weak force chains decrease with increasing friction coefficient, and the density of the blank part depends on the direction of the entire force chains (vector sum of the force chains). Under the strength of the force chains with slight changes and when the entire force chains are inclined in the densification direction, the density of the compacted blank part increases.