DISCRETE ELEMENT METHOD SIMULATION OF RICE GRAIN STACKING CHARACTERISTICS

Accurately determining the angle of repose for irregular and dispersed agricultural grain materials requires a simulation model that effectively represents the actual grain shapes and utilizes numerical methods to analyze their stacking behavior. This study focuses on "Yongyou 15" rice grains, employing 3D raster scanning technology to obtain precise contour data. Through a reverse modeling process, a detailed 3D geometric model of the grains was developed, resulting in a discrete element model comprising 618 grains of varying diameters, created using granular polymer theory. Discrete element analysis software (EDEM) was integrated with MATLAB image processing to simulate the falling and stacking process of the rice grains within a stainless steel bottomless cylindrical tube. The contour of the grain heap was analyzed using linear fitting, followed by a micro-mechanical investigation of the grain heap structure. The analysis indicated that the pressure depression within the heap is caused by the oblique transmission of contact forces. The simulated angle of repose under experimental conditions was 31.29°±0.41°, differing by only 0.81% from the actual measured angle of 31.04°±0.21° obtained through physical stacking experiments. These results demonstrate that combining numerical simulations with image feature extraction is a reliable and efficient method for assessing the stacking properties of agricultural materials.