DEM Model of Wheat Grains in Storage Considering the Effect of Moisture Content in Direct Shear Test

Abstract

Discrete Element Method (DEM) modeling was conducted for predicting strength properties of stored wheat grains in different levels of moisture contents, to extend the knowledge of grain storage beyond current experimental studies in the future. The main features of agricultural and food materials that make them different from mineral materials are strong influence of Moisture Content (MC) on mechanical behavior. Published data on grain and bulk properties of wheat relevant to DEM modeling were reviewed by considering the effect of MC. The shape of grains was modeled by Multi Sphere Method (MSM) and the interaction between grains was represented by linear and nonlinear frictional elastic contact models. The effect of MC was considered in simulation through an innovative procedure. The initial test was performed to choose the best models to perform the simulation. Statistical comparisons with relevant experimental result were conducted on simulation data. It has been proved that the DEM is able to capture the variation of strength properties of wheat with MC of grains. It is observed the simplest shape of grain models would allow us to obtain quite closely prediction of wheat strength parameters. Also the linear elastic contact model has more capability in representing the form of strength properties variation with MC. This suggests that the modeling is a useful tool in the study of mechanical behavior of wheat and other cereal grains during storage processes as well as provision of data necessary in the future design of appropriate machinery and structure.

Determining the Functional Characteristics of Wheat and Corn Grains Depending on Storage Time and Temperature

“…In light of this, the angle of internal friction decreased due to the decrease in the grain moisture level. The angle of internal friction has previously been found to decrease linearly with decreases in grain moisture content for wheat grains (Sarnavi et al 2013) and some hybrid corn varieties (Ozturk and Esen 2013), but the effects of storage time and temperature on the angle of internal friction had not been previously investigated.…”

Discrete element method as an approach to model the wheat milling process

“…The measured values of whole particles and fraction [1] for size, size distribution, density, shear modulus, coefficient of static and rolling friction, and coefficient of restitution were used as input parameters. Published literature values of Poisson's ratio and shear modulus values were used [19,20,21]. All input parameters are listed in Table 2.…”

Studies on Moisture Effects on Powder Flow and Mechanochemical Improvement of Powder Flowability

“…This often applies when modelling the rheology of moist powders consisting of particles of hygroscopic properties, like in the case of many plant materials. The moisture can substantially change the properties of powder bed particles and this is often not accommodated during routine DEM calculations, except for a few examples [3,4]. As a result the calculated data deviate substantially from those obtained experimentally and the level of the observed discrepancy could be a reliable measure of the rheological characteristics alteration due to moisture content in a powder bed.…”