Simulation analysis and experiment of ploughing process in northwest arid region based on discrete element method

<bold>Objective</bold> In addressing the problems of poor tillage performance and high tillage resistance in the operation of existing moldboard ploughs in the arid regions of Northwest China，a moldboard plough body surface is designed using the horizontal straight element line method.Equations for curve generation，variation of element line angles，and a plough body tillage resistance model are established. <bold>Method</bold> The discrete element software EDEM was used，and the Hertz-Mindlin with JKR contact model was selected as the soil contact model.The Box-Behnken response surface simulation test was completed and the multi-objective optimization of the regression model was carried out by taking the element line angle，the tangent angle at both ends of the guide curve and the installation angle as the test factors，the tillage resistance and the soil throwing distance as the evaluation indexes.Tillage simulations were performed using the optimized parameter combination for the plough body surface，and the rationality of the plough body surface parameter optimization was further analyzed by comparing the sectional view of soil disturbance and soil motion clouds at different stages before and after optimization. <bold>Result</bold> Results reveal that the minimum tillage resistance（2 626.59 N）and a relatively large soil throwing distance（451.62 mm）are achieved with an element line angle of 40.43°，tangential angle at both ends of the guiding curve of 107.01°，and an installation angle of 27.16°.Furthermore，the soil disturbance analysis revealed that the optimized plough body surface performed better than the non-optimized one in terms of lifting the soil and inducing soil motion. <bold>Conclusion</bold> Through field experiments，it is verified that the stability of tillage depth，residual stubble coverage，and the breakage rate of soil of the optimized moldboard plough all meet the requirements of national standards.The field experiment results for tillage resistance and soil throwing distance are 2 795.43 N and 423.57 mm，respectively.The relative errors compared with the simulation experiments results were 6.43% and 6.21%，respectively，falling within a reasonable range.The field experiemtns validate the rationality of the structural parameter design of the moldboard plough.