ASSESSMENT OF SIGNIFICANCE AND SELECTION OF CONTACT MODEL PARAMETERS WHEN SIMULATING PEAS SEEDS USING THE DISCRETE ELEMENT METHOD

An integral part of technological operations in agriculture during sowing, harvesting, transportation and post-harvest processing is the impact of the working parts of machines on crop seeds. To increase the efficiency of machines and reduce seed injury, it is necessary to improve the design and technological parameters of the working units. Currently, the most promising method for theoretically substantiating the parameters of machines working with seeds and improving their design is modeling using the discrete element method. The study is carried out to substantiate the parameters of the contact model of discrete elements when modeling pea seeds. The parameters of the contact model were justified based on the results of testing on the angle of slope and arch when pouring seeds. To analyze the angle of repose and vault, a transparent rectangular container was used, when seeds were poured out of the upper part of which, the remaining seeds formed the angle of the vault, and the crumbled ones formed the angle of repose. Evaluation of the coefficients of the regression equations for changes in the angles of the arch and slope when shedding seeds in a container from the parameters of the selected contact linear viscoelastic model made it possible to establish a significant parameter - the coefficient of dynamic friction between particles. The nature of the change in the angle of repose of pea seeds from moisture is identical to the change in this angle for particles modeled by the discrete element method, with their recovery coefficient v = 0.2 and the coefficient of dynamic friction between them fd = 0.15...0.17. The dependences of the angle of repose on the moisture content of pea seeds and the coefficient of dynamic friction between particles obtained during the implementation of experiments represent a nomogram for choosing the coefficient of dynamic friction between particles fd for a contact linear viscoelastic model depending on the moisture content of pea seeds when modeling using the discrete element method.