Research On Parameter Optimization Of Cross-Slot Opener Based On The Discrete Element Model Of Root-Soil Complex

Less no-till seeding is a key part of implementing conservation tillage.Cross slot opener is a new type of opener applied to less no-till sowing.In Shanxi Guanzhong biannual zone,wheat roots are closely bonded to the soil during no-till sowing of corn,and the roots have a great influence on the working resistance and soil disturbance during trenching of the opener.In this paper,the discrete element method is used to establish a simulation model of wheat root-soil complex for less no-till sowing conditions,and a combination of numerical simulation and field tests is used to optimize the cross-slot trencher cross blade structure parameters.The main research contents and conclusions are as follows:(1)Establishing and analyzing the working resistance model of cross slot trencher cross blade.The mathematical models of the working resistance between the crosscutter entry angleα,the backward sweeping angle β and the downward tilting angle γ of the crosscutting knife were established respectively,taking the crosscutting knife as the research object.Anaconda software was used to analyze the mathematical model and investigate the influence trend of the change of the crosscutter structure parameters on the working resistance,and the preliminary determination of the values of the crosscutter entry angle α,backward sweep angleβ and downward tilt angle γ were 20°～40°,0°～40° and 0°～40° respectively.(2)Construction of discrete element model of wheat root-soil complex.Firstly,the wheat root system model was constructed based on the Hertz-Mindlin bonding bonding model with a rapid particle filling method.Nine initial parameters were screened by Plackett-Burrman test,and it was found that particle shear modulus and interparticle bond radius and bond stiffness had significant effects on the ultimate shear force of wheat root system.Based on the optimal interval of significance parameters determined by the steepest slope climbing test,a secondorder regression model of ultimate root shear and significance parameters was established and optimized based on the Box-Behnken test results.Second,the key parameters of the wheat root-soil interval were calibrated using the steepest climb test method.Finally,the calibrated root-soil complex model was validated,and the results showed that the relative error between the simulated shear resistance and the actual shear resistance was 7.35%.The relative error between the simulated shear resistance and the actual shear resistance was 7.35%,indicating that the root-soil complex model of wheat based on the discrete element method can be used to simulate the actual soil environment in the field.(3)Optimization of trencher crosscutter parameters based on a discrete element model of wheat root-soil complex.A simulation model of root-soil-crossgroove opener interactions was established,and single-factor and quadratic orthogonal rotational combination tests were conducted with the opener working resistance and soil disturbance coefficient as evaluation indexes.The results show that the main and secondary factors affecting the working resistance of the trencher are: soil entry angle α,downward angle γ and backward angle β,and the main and secondary factors affecting the soil disturbance coefficient are: soil entry angle α,backward angle β and downward angle γ.The Optimization module of Design-Expert software is used to analyze and solve the problem,and the best combination of parameters is The best combination of parameters is 21.69°,28.99° and 20.48°.(4)Field operation performance and simulation model validation of the cross slot trencher.The optimized cross cutter was machined and assembled and tested in the field.The test results show that the average working resistance and soil disturbance coefficient of the optimized cross slot trencher are 568N and 39.57%.The relative errors between the field test results and the simulation results of root-soil complex model were less than 15%,indicating that the established root-soil complex model can simulate the actual soil in the field more accurately.