DEM simulation of straw-soil-cutting system interactions for performance assessment of a spin-descent straw cutter

Abstract

Accurate measurement of straw mulch mass requires effective separation of residues inside and outside the sampling frame. To achieve this, a novel spin-descent straw cutter was designed, integrating a stabilizing ring and a rotating and descending separation column. The stabilizing ring pressed the straw to reduce movement, while the separation column simultaneously rotated and descended to cut and separate the straw at the frame boundary, representing an integrated structure not previously reported. A discrete element method (DEM) model was established to simulate straw-soil-cutting system interactions, and three blade types (sawtooth, corrugated, and notch-shaped) were compared. Response surface methodology and multi-objective optimization were employed to balance cutting rate, power consumption, and soil disturbance area. Bench tests confirmed the DEM predictions with errors within 12 %. Results demonstrated that the sawtooth blade achieved the most favorable trade-off, with optimal parameters of 287 N downward force, 230 rpm rotation speed, and 10 mm insertion depth. The study highlighted the unique suitability of the spin-descent cutter for automated straw mulching detection and provided a validated simulation–optimization framework to inform future cutter designs and broader applications in conservation tillage.