Quasi-static and dynamic compaction of granular materials: A strain-activated statistical compaction model and its evaluation

Abstract

The cold die compaction behaviors of granular material are investigated and a strain-activated statistical compaction model is developed to address its deformation mechanisms, namely particle rearrangement and deformation. The compaction equation is explicit in form and only contains four parameters. Its effectiveness is validated with multi-particle finite element simulation and experimental data. The results show that the compaction model can capture the main features of the nominal compression stress–strain curves of 2D/3D granular materials with different initial relative densities. The dependence of the four parameters in the compaction equation on the initial relative density are analyzed and corresponding quantitative statistical relationships are determined, which takes the same form for 2D and 3D granular materials. It is found that the difference in the quantitative statistical relationships between 2D and 3D granular materials cannot be neglected and the result of 3D multi-particle finite element model is more reasonable, which is verified by the existing experimental data of Al powder. Finally, the statistical compaction model can be applied to characterize the dynamic compaction behaviors of granular materials, and the stress behind the shock front and the shock speed predicted by the model agree well with the finite element results.