Comparative study between Drucker-Prager/Cap and modified Cam-Clay models for the numerical simulation of die compaction of pharmaceutical powders

Numerical simulation with finite element method is commonly used to model the process of die compaction. In pharmaceutical field, the Drucker-Prager/Cap (DPC) model is by far the most used to study the mechanical behavior of the powder. Another classical model but less used model, the modified Cam-Clay (MC-C) model, is introduced in this study. The main advantage is that the model parameters are easier to determine for MC-C model than for DPC model. The yield surface of the MC-C model is an elliptical curve. This model was compared to DPC model in order to assess its ability to describe the powder behavior in compression. Experimental tests were done to characterize the parameters of both models and the simulations were performed. The global behavior of the powder in compression was assessed from the equations of the models and the plots of compression curves. The spatial distributions of the relative density and axial stress were studied to compare the local behavior of the compact (stress concentration, areas of low/high density). The results obtained from the two models were nearly identical in the case of flat-faced punches but also when using concave-face punches. This means that the MC-C model is able to well describe the die compaction of pharmaceutical powder. (C) 2017 Elsevier B.V. All rights reserved.