Numerical Investigation of Stress Distribution during Die Compaction of Food Powders

A numerical method is presented to determine the internal stress distribution in powder compacts during uniaxial die compaction using the finite element method. A continuum-based analysis was carried out considering the powder body forming a tablet as an elastic-plastic continuum. Compaction behavior and mechanical material properties were defined using a modified density-dependent Drucker-Prager cap (DPC) material model. In addition, a nonlinear elasticity law was adopted to describe the nonlinear unloading behavior observed for the tested amorphous and crystalline food powders. The constitutive model was calibrated using an experimental procedure based on uniaxial die compaction experiments. All material-dependent parameters were determined experimentally using a fully instrumented hydraulic tablet press with a single-ended compaction profile. Numerical simulations of the compaction process were carried out by the commercial finite element software package ABAQUS using the calibrated material model and experimental friction data. The simulation results were in good agreement with experimental data, which demonstrated the suitability of this method to investigate internal processes during tableting.