A modified Drucker-Prager Cap model for die compaction simulation of pharmaceutical powders

Modelling the mechanical behaviour of pharmaceutical powders during compaction

The effect of wall friction in the compaction of pharmaceutical tablets with curved faces: a validation study of the Drucker–Prager Cap model

Analysis of tablet compaction. I. Characterization of mechanical behavior of powder and powder/tooling friction

Numerical and experimental investigation of capping mechanisms during pharmaceutical tablet compaction

Powder die compaction is modelled using the finite element method and a phenomenological material model. The Drucker–Prager cap model is modified with the goal to describe the formation of cracks during powder transfer, compaction, unloading, and ejection of the parts from the die. This is achieved by considering the cohesive strength and the cohesion slope, which characterise the current strength of the powder compact in the Drucker–Prager model, as state dependent variables. Evolution equations are formulated for these variables, so that the strength increases by densification and decreases by forced shear deformation. Some of the parameters appearing in the evolution equations are determined from measured green strength values. An iron based powder (Distaloy AE) is used for the experiments. Examples are shown to demonstrate that the density distribution can be calculated accurately as compared with an experiment, that cracking can be modelled at least qualitatively correctly, and that the compa...

H. Riedel

Papers

Numerical simulation of metal powder die compaction with special consideration of cracking