Powder compaction is of paramount importance in various engineering and industrial processes, providing valuable insights into production across diverse fields by elucidating the compaction process and post-compaction physical properties of soft grains. However, the compaction process of highly deformable grains with intricate contact behaviors remains inadequately understood due to limitations in experimental and numerical simulation tools. To address this knowledge gap, this study employs the multi-particle finite element method (MPFEM) with cohesive contact to investigate the mechanical response of cohesive powders during compaction and decompression. The validity and efficacy of the proposed MPFEM are established through contact problems, and it is subsequently utilized to systemati...[ Read more ]

Powder compaction is of paramount importance in various engineering and industrial processes, providing valuable insights into production across diverse fields by elucidating the compaction process and post-compaction physical properties of soft grains. However, the compaction process of highly deformable grains with intricate contact behaviors remains inadequately understood due to limitations in experimental and numerical simulation tools. To address this knowledge gap, this study employs the multi-particle finite element method (MPFEM) with cohesive contact to investigate the mechanical response of cohesive powders during compaction and decompression. The validity and efficacy of the proposed MPFEM are established through contact problems, and it is subsequently utilized to systematically simulate the compaction of cohesive powder components under various loading paths, including unconfined compression, triaxial compression, and cyclic loading. The simulation results are meticulously analyzed and discussed, encompassing the elastic, yield, damage, and hysteretic responses of the compacted powder grains.

Nonetheless, the mesh-based numerical simulation method possesses inherent limitations, particularly its susceptibility to mesh distortion problems. Therefore, the second part of this study introduces a novel computational framework that integrates total Lagrangian smoothed particle hydrodynamics (TL-SPH) with an adaptive contact model for modeling soft granular matter. The contact model, utilizing virtual TL-SPH particles, accurately and flexibly accounts for the frictional and cohesive contacts commonly observed in soft granular systems. This scalable framework enables parallel computations using modern graphics processing units (GPUs) and undergoes thorough validation while being applied to simulate the compaction of soft powders. The results demonstrate the robustness and efficiency of the proposed computational framework in capturing frictional sliding and cohesive contacts in grains undergoing extensive deformations within large soft granular systems. It serves as an effective numerical tool for enhancing our fundamental understanding of the complex mechanical behavior of soft granular materials, which is crucial in the context of soft matter processing.

Additionally, within the TL-SPH computational framework, this study presents an algorithm for heat conduction and thermal contact based on an Eulerian framework. By comparing the results with theoretical solutions and established numerical simulation methods, this algorithm accurately captures the influence of temperature on compaction behavior and heat transfer processes within the compacted packing. To demonstrate the effectiveness and applicability of the proposed method, the compaction behavior of 5083 aluminum alloy powder grains is examined at different temperatures, ranging from room temperature to slightly below the melting point of the metal material. This investigation encompasses various compaction techniques commonly employed in powder metallurgy, such as cold, warm, and hot pressing, enabling a comprehensive exploration of temperature’s influence on the macroscopic response and microstructural evolution during the compaction process. The study systematically analyzes the mechanical response, microscopic inter-grain contact, grain shape, and grain movement within the packing system during compaction. Additionally, it explores the thermal-mechanical coupling behavior of dense packing during the early stage of metal powder sintering. Through analyzing changes in the distribution of von Mises stress, contact force, and grain shape, the densification behavior resulting from heat conduction within the packing is examined and analyzed at the microscopic level.