Zhengpu Chen

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

Abstract: The discrete element method (DEM) has become popular for modeling the behavior 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 optimization 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 corn and wheat kernels were determined with a combination of direct measurements and calibration tests and validated against bulk material tests. The characterization 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 percent error of the bulk density test was 4.0% for corn and 8.4% for wheat, and the error in the angle of repose test was 0.4% for corn and 1.3% for wheat. DEM simulations of bulk density and angle of repose tests using the parameters measured with the characterization tests are able to accurately predict the experimental measurements.