Numerical and experimental study of multilevel force chain networks in metal powder compaction

Abstract Powder compaction is the most fundamental and crucial process in powder forming. To elucidate the roles of multilevel force chains in powder compaction and forming, a new method for classifying force chains by force chain strength is proposed for the complexity of multilevel force chains in the actual iron powder compaction process. A discrete element model of iron powder compaction was developed and validated using the Heckle equation and experimental data. The results of the study indicate the following: Prior to the initiation of compaction, gravitational forces concentrate force chains predominantly within the lower region of the compact. As compaction proceeds, force chains progressively redistribute from the lower to upper regions of the compact, with finer particle size distributions enhancing chain formation. 300 MPa serves as the critical threshold for force chain restructuring and accelerated densification. The average force chain transfer index for different levels of force chains increases with increasing compaction pressure. The particle compositions of force chains at all levels is concentrated in force chains of particle compositions number less than 6. The directionality of the force chain shows some anisotropy, and gradually concentrates on the Y -axis directions with the increase of the grade. This multilevel force chain analysis clarifies their role in compaction mechanics and provides theoretical insights for optimizing compaction quality. It has theoretical and guiding significance for the improvement of forming quality.