Effects of ultrasonic vibration-assisted cutting on tillage blade performance and soil fragmentation characteristics under different soil moisture contents

In response to the challenge of high cutting resistance experienced by the blade during tillage operations, this study proposes a resistance reduction method based on ultrasonic vibration-assisted cutting. Five types of soil with different moisture contents were selected as the research objects, and a dynamic model of the blade and soil particles under ultrasonic vibration was constructed. The simulations employed the discrete element method (DEM) coupled with a contact model to calibrate soil models with different moisture contents. The cutting force and cutting energy in both the ultrasonic vibration-assisted cutting (UVAC) and conventional cutting (CC) modes were analyzed. Least significant difference and regression analysis were used to determine the differences between the two modes. Additionally, the force and velocity of soil particles under both cutting modes were examined to quantitatively and intuitively assess the fragmentation between particles. The results demonstrated that the simulation results were largely consistent with the bench experiment results. The simulation analysis effectively captured the trends in cutting force and cutting energy observed in the actual cutting process and revealed the microscopic changes in soil fragmentation. For all five moisture contents, the cutting force in both modes gradually increased with cutting depth, while the cutting force in UVAC mode was significantly reduced. As moisture content increased from 10 % to 30 %, the cutting energy for both modes decreased, with higher moisture content corresponding to lower energy requirements during cutting. Notably, the cutting energy in UVAC mode was reduced by more than 60 % across all moisture contents. Furthermore, UVAC mode enhanced the force and velocity of soil particles, facilitating the fragmentation of interparticle bonds. However, the electrical energy in UVAC mode was consistently higher than that in CC mode. In conclusion, this study demonstrates that using ultrasonic vibration-assisted blade for soil cutting effectively reduces cutting force and cutting energy while enhancing the fragmentation of soil particles. These findings provide a new research direction for the development of resistance reduction equipment in agricultural tillage operations. • Proposed ultrasonic vibration-assisted cutting (UVAC) to reduce blade resistance. • The DEM was adopted to construct soil models with different moisture contents. • The UVAC mode reduced the cutting force and cutting energy of blade. • The UVAC mode facilitated the fragmentation between soil particles.