Assessment of particle rearrangement and anisotropy in high-load tableting with a DEM-based elasto-plastic cohesive model

摘要

The goal of the present study is to assess the extent of particle rearrangement and the degree of anisotropy for uni-axial compaction of microcrystalline cellulose (MCC) by Discrete Element method simulations. The elasto-plastic cohesive hysteretic Edinburgh contact model is hereby considered. First, a calibration strategy for all required collisional, frictional, or cohesion input parameters is presented. A dual approach combining direct determination tests (e.g., nano-indentation or inverse gas chromatography) and indirect fitting tests (e.g., tumbling drum test) provides the final set of property values. Second, the uni-axial compaction of MCC for a range of target compaction pressures and different primary particle dispersities (mono- and polydisperse) is conducted. The anisotropic behavior of compaction is analyzed by computing averaged quantities such as the deviatoric term and the maximum difference between characteristic roots of the fabric tensor. The results depict a remaining degree of anisotropy after compaction, depending on the maximum compaction pressure and particle dispersity, which does not fully recover after powder decompression.