Calibration of microscopic parameters of granular materials

The main objective of this study is to calibrate Discrete Element Modeling (DEM) input parameters for Vietnamese DT84 variety soybeans. For this purpose, the shape of the soybeans was firstly analyzed through digital images (captured by an imaging platform), which enabled the deviation of the shape of particles compared to a sphere through shape indicators to be quantified. Secondly, the physical characteristics of the soybeans (size distribution and gravimetric properties) and the coefficient of static friction between particles and material surfaces were measured by experimentation. The rest of the DEM input parameters were calibrated by combining selected particle flow experiments and corresponding DEM simulations, including bulk density cylinder, silo discharge and inclined cylinder. The final set of DEM input parameters was compared with previous research in the literature for other varieties of soybeans, showing strong correlation. This study proves that: (i) spherical particles can be used to model DT84 soybeans in DEM simulations and (ii) the equivalent diameter of the grains obtained from image analysis can be employed to approximate particle weight. The DEM input parameters of soybean obtained from this work could help enhance the design and development of seeders, by exploring the contact behavior between particle flow and machine parts.