Design and performance experiment of opener based on bionic sailfish head curve

Abstract: In order to reduce working resistance of seeding opener and soil disturbance, the opener based on bionic sailfish head curve was designed. The two-dimensional (2D) drafting software of CATIA (computer aided three-dimensional interactive application) is used for getting the sailfish head profile curve. The head profile curve segments of sailfish is obtained based on the relative positional coordinates of points. Using the agronomic requirements and the parameters of the head profile curve segments of sailfish determine the structural parameters of opener. The main structure parameters of the opener are penetration angle of 30° and penetration clearance angle of 6°. Due to the interaction of the soil and the opener during movement is a complex process, the discrete element simulation from microscopic point of view is performed to study the interaction between the opener and the soil. The discrete element model of soil is established. In order to ensure the accuracy of test data, the related parameters are calibrated. Soil resistance is influenced by working depth and soil moisture content. At the same time, the relationship between working depth and soil disturbance is obtained. The software of EDEM (enhanced discrete element method) is used for the simulation analysis of working resistance and soil disturbance of the opener. Soil moisture content is 12%±1%, 16%±1%, and 20%±1%, working depth is 30, 60, and 90 mm, respectively, and forward speed of the opener is 0.5 m/s. Under these working conditions, the working resistance of the opener and its disturbance to soil are studied. Simulation results show that the working resistance of the opener increases with the increasing of soil moisture content, and also increases with the increasing of ditching depth, the horizontal resistance is between 19.70 and 74.60 N, the vertical resistance is between 9.37 and 26.90 N, the width of the disturbance in the opener is between 140 and 200 mm, and the soil returning depth is between 19 and 80 mm. In order to prove the credibility of the simulation results of the EDEM and the rationality of the opener, the experiments are carried out in the agricultural soil test laboratory of the northeast agricultural university. Simulation of work resistance and test results showed that the trend of change in work resistance was roughly the same, the relative error were between 5.04% and 27.08%. Compared with the experimental results, the simulation results were almost the same as the experimental results, and the difference of the ditching depth was between ?2.5 and 0.67 mm, but the simulation results of the disturbance width were between 106.7 and 140 mm, smaller than the experimental results, which may be related to the larger particle size of the simulated particles. The trend was basically the same. The opener based on bionic sailfish head curve and the arc-type opener were selected for contrast experiment. The results showed that the performance of the opener based on bionic sailfish head curve was better than the arc-type opener. The research shows the feasibility of using the discrete element method to simulate opener's working resistance and soil disturbance, and provides a convenient method for the opener design.