Study on the modeling method of sunflower seed particles based on the discrete element method

A modeling and simulation method was developed to comprehensively describe and build discrete element model for non-spherical particles based on the discrete element method (DEM). To popularize the application of sunflower seeds in computer digital simulation technology, the motion patterns and dynamic response characteristics of sunflower seeds in key processes such as sowing and harvesting are explored with the help of discrete element analysis methods to optimize the dimensional parameters and structural performance of related mechanical components. This paper takes edible sunflower seeds 1013 as the research object, and proposes a discrete element analysis model building method for individual sunflower seeds and groups of sunflower seeds particles by testing and analyzing the triaxial dimensions and three-dimensional volumes of sunflower seeds and the shape simplification of the seeds. 6 sunflower seed multi-sphere models (25 sub-spheres, 28 sub-spheres, 31 sub-spheres, 34 sub-spheres, 37 sub-spheres, 40 sub-spheres) with different accuracy and 2 sunflower seed polyhedral models (cuboid and triangle pyramid) with different shapes were established using the multi-sphere and polyhedron filling methods. The physical tests and angle of repose simulation tests were applied to measure and calibrate the intrinsic parameters and contact parameters of sunflower seeds. The physical test results of the bulk density and angle of repose are compared with the simulation test results to verify the feasibility of the discrete element modeling method for sunflower seeds proposed in this paper. The results show that the simulation results of bulk density and angle of repose are closer to the experimental results when the multi-sphere model is 31 sub-spheres and the polyhedral model is cuboid, considering fewer spheres and faster simulation rates. And the accuracy and applicability of the discrete element model and parameters of sunflower seeds are further verified through the simulation test of the productivity of the spiral conveying device of the 4ZXRKS-4 sunflower combine harvester test bed.