Multi-contact elastoplastic contact model for DEM-simulations of high load compaction derived from realistic microstructure

点击翻译按钮获取中文摘要

The aim of the present project is the further development and validation of a new elastic-plastic multi-contact model for the Discrete Element Method Simulation (DEM) of compaction and tabletting, e.g. of pharmaceutical powders, for better prediction of micro- and macromechanical properties. The high plastic particle deformations as well as the low porosities are challenges so far, which prevent the DEM from being used as a standard tool for process and formulation design in tabletting, respectively compacting. A multi-contact contact model for the DEM has already been established and successfully tested by the applicant for predominantly elastic deformation and medium degrees of compaction. However, in order to be able to model industrially relevant processes such as powder compaction and tabletting, the plastic deformation of the material and the change in the contact surfaces under high compressive stress must be additionally recorded and implemented in the existing model. The aim is to model the multi-contact contact model on the basis of mechanistic dependencies and to calibrate and validate it with experimental data.To realize this, a small number of particles will be compressed in a microcomputer tomograph (µCT) in the initial phase. Subsequently, the experiments will be analyzed with respect to structural parameters. In combination with the simulation methods Finite-Element-Method (FEM) and Discrete-Element-Method (DEM), the change of microstructural parameters and their influence on contact forces will then be systematically investigated. In addition, further complex physical dependencies are to be identified and integrated into the new contact model by means of automatic partial model evaluation, model development and parameterization using a genetic algorithm. The validation and final adaptation of the multi-contact model will then be carried out by means of simulation and experimental investigation of the compaction of the model systems used in a fully equipped "Compaction Simulator".