(116h) Revisiting Johanson's Rolling Theory of Granular Solids

Revisiting Johanson’s Rolling Theory of Granular Solids

Matthew Brown, Matthew Pruitt, Bryan J. Ennis*

Department of Chemical Engineering, The University of Tennessee at Chattanooga

*Corresponding author, bryan-j-ennis@utc.edu

Roll pressing is a common dry granulation technique used throughout a variety of processing industries, ranging from production of battery cathode or catalysts powders to pharmaceutical granulate which is later tableted.  Roll pressing has several advantages over alternative granulation techniques.  In particular, it is a dry, continuous process, capable of recycle.  Johanson developed an early rolling theory of compaction based on a solution of the stress equations of equilibrium by the method of characteristics [1].  In this work, we revisit Johanson’s theory and its underlying assumptions and boundary conditions. Finite element methods (FEM) are applied to the roller compaction for a granular continuous media using an Arbitrary Lagrangian-Eularian (ALE) framework.

Experimental studies by Bindhumadhavan et al.[3] have validated the effects of powder material properties on nip angle and peak pressure development as predicted by Johanson’s theory.  More extensive experimental and FEM studies were later undertaken by Cunningham et al. [2] and Balicki [3].  However, these previous FEM studies of roll compaction have relied on the ABAQUS Drucker Prager plastic material model alone, which is insufficient in material characterization [3].

This work extends these studies to include additional material models (both plastic and geotechnical) utilizing LS-DYNA. Such models incorporate readily determinable material properties measurable by shear cell and compaction measurements.  The impact of material models properties, wall friction, gap distance and roll speed are explored, as well as the sensitivity of press performance to these parameters.

Keywords: Roller compaction, Granular Solids, Roll pressing, Granulation, Finite Element

1. Johanson (1965), ASME, Journal of Applied Mechanics Series E, 32(4), 842–848).
2. John C. Cunningham et al. (2010), Computers & Chemical Engineering, Vol. 34, pg. 1058–1071.
3. Marcin Balicki (2003), Ecole Des Mines D’Albi Carmaux, Numerical Methods for Predicting Roll Press Powder Compaction Parameters.