Modelling soil-rotor blade interaction of vertical axis rotary tiller using discrete element method (DEM)

Vertical-axis rotary tillers are preferred over other soil-engaging tools for inter-culture operations due to their superiority in avoiding tillage pan formation, facilitating drainage, and operability at higher forward speeds. To optimize their design and operation, and to promote sustainable agricultural practices, a greater understanding of the kinematics, dynamics, and soil-structure interaction of vertical axis rotary tiller is required, along with the optimization of required energy. In this study, discrete element method (DEM) is used to analyse the interaction between soil and rotor blades, by incorporating the Hysteric Spring Contact Model along with linear cohesion model v2. Soil-rotor blade interaction DEM model is developed using Altair® EDEM® to analyse the effect of u/v ratio (2.13, 2.90, 3.70, and 4.44) and average operating depth (30 mm, 50 mm, and 70 mm) on draft and torque requirements for the rotor blade, as well as experimentally validating the simulation in a soil bin. In this study, lower u/v ratios in vertical axis rotary tillers demand higher torque for larger soil volumes. Additionally, torque rises with operating depth, owing to increased soil volume and strength. The simulated results closely followed the measured draft and torque for all combinations of u/v ratio and operating depth (R² 0.96 and 0.99). These findings indicate the DEM model as a dependable approach for modelling the performance of rotary tillers under different soil conditions.