Optimization design and performance study of a subsoiler underlying the tea garden subsoiling mechanism based on bionics and EDEM

Abstract

Considering the problems of high tillage resistance, high energy consumption, and failure to break the plow pan in subsoiling caused by the high viscosity of tea garden soil, a new design method of a subsoiler underlying the subsoiling mechanism based on structural bionics and the discrete element method is proposed. Taking the largest toe of mole cricket's forefoot as the bionic object, the biological information of the contour of mole cricket's toe was extracted using the methods of image processing and reverse engineering, and the edges of its outer and inner contours were obtained. Combined with the structure of an existing subsoiler, initial point cloud data of a bionic subsoiling shovel were mapped by the methods of proportional amplification and rotation. Taking the minimum sum of outer and inner contour fitting errors as the optimal objective function and selecting high-order polynomial as the fitting function, the optimization model of the outer and inner contour point cloud fitting function was established. The optimal fitting function of the outer and inner contour point cloud was obtained, and the bionic subsoiler model was established based on these two optimal functions. In the study of the discrete element, four soil particle models were proposed based on the actual shape of the cohesive soil of a tea garden. Based on the principle of discrete elements and the agronomic requirements, a modeling method of the plow pan soil was proposed. First, the adjacent soil particles at the bottom were connected by bonding, and the soil with large porosity was squeezed by the preset force to form the plow pan soil. Then, six tillage layers were added above the plow to form a soil structure model of the tea garden. The bionic subsoiler was assembled into a four-bar subsoiling mechanism. The process of the subsoiling mechanism acting on the soil was analyzed by the co-simulation of ADAMS-EDEM and compared with the common subsoiler. The results showed that the bionic subsoiler, compared with the common subsoiler, reduced the tillage force in the horizontal direction by 16.34% and in the vertical direction by 24.53%, reduced energy consumption by 9.64%, increased the damage to the plow pan by 5.10%, and caused greater disturbance to the internal soil. The influence of different driving speeds on the tillage performance was studied, which provides a theoretical reference for the better selection of the working speed for subsoiling.