Quasi-static diametrical compression of characteristic elastic-plastic granules: Energetic aspects at contact

Comminution processes have traditionally been considered as empirical endeavors, with great difficulties in analyzing, predicting and controlling the observed behavior. Process industries have faced serious problems, ranging from poor product quality control up to managing product quantity losses due to unexpected attrition and breakage events. After a decade of ardent research, there has been a notable advancement in our understanding of granular behavior under mechanical stresses. However, far less is known about the energetic aspects occurring at such conditions. In this article, we present critical information from an energetic perspective concerning the deformation and breakage behavior of characteristic elastic plastic granules under quasi-static compressive forces, studied using single granule diametrical compression tests at a constant strain controlled loading velocity. The force displacement behavior has been approximated using the Hertz model (Hertz, 1882) for elastic loading, the Tomas model (Tomas, 2007a) for elastic plastic loading and the Stronge-Antonyuk correlations (Stronge, 2000; Antonyuk, 2006) incorporated Hertz model (Hertz, 1882) for elastic unloading with additional displacements due to apparent viscous effects. The rate independent specific energy characteristics have been studied and a corresponding energetic coefficient of restitution has been derived. A comparison of the energetic characteristics at primary breakage of fresh and pre-loaded granules has been presented using breakage probability functions. The phenomenon of strain hardening during localized repetitive compressive loadings has also been analyzed. Furthermore, the influences of granule size, moisture content and stressing intensity have been considered in each of the investigated entities. (C) 2014 Elsevier Ltd. All rights reserved.