Evaluating the influence of straight-plain types of rotary tiller blades with various edge curves on maize residue using DEM

Abstract

In no-tillage and minimum tillage systems, the abundance of crop residues and stubble left on the soil surface poses considerable challenges in seedbed preparation and residue handling for seeders in maize-wheat rotations. This study utilised the Discrete Element Method (DEM) to develop models illustrating the interactions between plain-straight blades featuring three edge-curves (Archimedean spiral, sinusoidal-exponential spiral, and logarithmic spiral) and maize residues, encompassing stubble and straw. Simulation experiments were employed to evaluate the soil disturbance, operational resistance, torque requirements, and residue-cutting efficiency of these various blade types at four initial static slide-cutting angles (ISSCAs: 35°, 45°, 55°, 65°). The simulation results exhibited an error of <7.5% compared to actual measurements of straw bending properties and soil cone index. The results showed that blade length, curvature, and dynamic slide-cutting angle range increased with higher ISSCA values. The elevation in slide-cutting angles notably enhanced the slide-cutting performance of the blade, leading to diminished torque requirements and draft forces within specific ISSCA ranges while improving residue-cutting efficiency. The stubble-cutting revealed more obvious soil disturbance than straw-cutting due to the adhesion between roots and soil. Notably, all three blade types exhibited increased vertical force and amplified soil disturbance area at 65° ISSCA during stubble cutting, primarily influenced by blade length. The Archimedean spiral blade demonstrated superior residue-cutting efficiency at 55° ISSCA while exhibiting reduced torque demands, operational resistance, and soil disturbance among all treatments. The findings help optimise the structure of plain-straight blades and field residue management.