Determination of the mechanical properties of maize grains and olives required for use in DEM simulations

The discrete element method (DEM) is a numerical technique specifically designed for the simulation of the mechanical behavior of granular materials (e.g., granular food or pharmaceutical products). To make full use of the potential of this technique, values relating to certain microscopic properties of the material under study must be known, yet the literature contains little information in this respect. Indeed, some of the values required are difficult to obtain experimentally, and there are no standardized procedures in place for their determination. The present work reports the experimental determination of values for several of the microscopic properties - the particle density, modulus of elasticity, particle-wall coefficient of restitution, particle-particle coefficient of restitution, and the particle-wall coefficient of friction - of maize grains and olives, required for use in DEM simulations. To make preliminary evaluation of the assay procedures, glass beads, a better known material, was also used. The apparatuses and experimental protocols employed are explained, the difficulties arising with each described, and the results obtained discussed. (C) 2012 Elsevier Ltd. All rights reserved.