Operational performance research of layered rotary tillage and ridging machine on for the sticky soil using DEM

To address the challenges of low soil fragmentation rates and high tillage resistance during land preparation for the sticky soil in southwest China, a double-shaft layered rotary tillage and ridging machine was designed to enhance the soil layer structure. It mainly composes deep rotation device, soil crushing device, ridging component, etc. This study employed the Discrete Element Method (DEM) to optimize the operational parameters of the double-shaft layered rotary tillage and ridging machine, compare the tillage performance between single-shaft and double-shaft tillage equipment, and simulate the effects of tillage depth on tillage performance. Following the Box-Behnken testing design principle, a regression model was established to relate all factors to the performance index. The independent variables included rotation speed of deep rotation device, horizontal distance, and rotation speed of soil crushing device, while the average energy consumption and number of topsoil broken bonds as the response variable. Results showed that the factors which influence soil crushing performance from big to small were rotation speed of soil crushing device, horizontal distance, and rotation speed of deep rotation device. The optimal parameters were that the rotation speed of deep rotation device was 260 r/min, the horizontal distance was 340 mm, and the rotation speed of soil crushing device was 430 r/min. A comparison of the working performance between single-shaft and double-shaft revealed that the double-shaft exerts a greater disturbance intensity on the topsoil. Specifically, the total number of topsoil broken bonds was 12.17% higher than that for the single-shaft, and the total number of topsoil broken bonds was approximately 1.5 times that of the subsoil broken bonds. As the tillage depth increases, the number of topsoil broken bonds tends to decrease, while the number of subsoil broken bonds, energy consumption, and traction resistance of rotary knife roll correspondingly increase. Field test results indicate that the surface soil fragmentation rates of the double-shaft layered rotary tillage and ridging machine and the traditional single-shaft rotary tillage ridging equipment were 93.74% and 69.46%, respectively. The double-shaft demonstrates an improvement in soil fragmentation rates by 24.28% compared to the single-shaft. These findings provide theoretical references for the popularization of double-shaft layered rotary tillage and ridging machine in the sticky soil area.