Combined DEM and Johanson model for ribbon density prediction in a roller compactor

Johanson (1965) developed a one-dimensional model for the stress acting on the powder in between the rolls of a roller compactor. Limited work has been performed regarding estimation of inlet stress; a parameter required for the estimation of ribbon density in a roller compactor. Due to the difficulty in the design and implementation of stress measurement systems, measurement of inlet stress is difficult experimentally. Therefore, a Discrete Element Method (DEM) based approach is proposed to get the inlet conditions which are used in the Johanson model to predict the ribbon density. The results indicate that the inlet stress and the corresponding pre-consolidated density obtained from DEM simulations were different for different process parameters. The combined methodology of using output from DEM simulations as an input condition for Johanson model yields a good prediction of the ribbon density with the inclusion of elastic expansion ratio (ribbon thickness/roll gap).