Determination of material and interaction properties of maize and wheat kernels for DEM simulation

Abstract

The discrete element method (DEM) has become popular for modelling the behaviour of grain kernels during agricultural production, processing, and transportation. DEM simulations provide both qualitative and quantitative information on particle flow, which helps improve the understanding, design, and optimisation of grain handling equipment. The accuracy of the DEM models is greatly affected by the model input parameter values, such as the grain kernel material and interaction properties. However, precisely and properly quantifying these properties remains a challenging task due to the irregular shapes of kernels and the heterogeneity of these biological materials. In this study, the DEM simulation material and interaction properties of maize and wheat kernels were determined with a combination of direct measurements and calibration tests and validated against bulk material tests. The characterisation tests include X-ray micro-CT scanning for acquiring kernel size and shape information, the use of a reciprocating pin tribometer for coefficients of friction, and an inclined surface drop test for calibrating the coefficients of restitution. The measured model parameter values were used in DEM simulations of two common bulk material tests: the poured bulk density test and an angle of repose test. The percentage error of the bulk density test was 4.0% for maize and 8.4% for wheat, and the error in the angle of repose test was 0.4% for maize and 1.3% for wheat. DEM simulations of bulk density and angle of repose tests using the parameters measured with the characterisation tests are able to accurately predict the experimental measurements. • Material and interaction properties of maize and wheat were determined. • Glued-sphere particles were generated based on 3D scanned models. • A calibration test was developed to determine the coefficient of restitution. • Tribometer test provided measurements of the grain kernel friction coefficients. • Image analysis was used to quantitatively compare angles of repose.