Research on the mechanism of residual film cutting and fracture via high-speed camera validation and discrete element simulation

• Construction of flexible thin film model based on discrete element method. • Process analysis of residual film cutting and crushing via high-speed photography. • Fracture simulation of residual film under combined tensile and shear stresses. • The qualified rate of the broken film in the broken film device is 89%. Mechanized crushing of agricultural residual film is crucial for recycling efficiency, but uneven crushing leads to short and unstable service life during reuse. This study proposes a novel discrete element modelling method based on the Tensile-Shear Hybrid Criterion, enabling simulation of tearing and deformation during cutting and enhancing tool performance. Through theoretical analysis and preliminary simulations, key parameters influencing cutting performance were identified. A three-factor, three-level Box-Behnken experimental design was implemented. The factors investigated were tool rotational speed, film pre-tension force, and the gap between moving and stationary knives, with tool energy consumption as the response. This approach enabled development of a mathematical model relating factors to response. The model was optimized using Design-Expert software, yielding an optimal parameter combination: tool speed of 1117.1 r·min⁻¹, pre-tension force of 0.783 N, and knife gap of 0.699 mm. Under these conditions, predicted energy consumption was 0.0334 J. To validate the simulation, a high-speed camera test platform was constructed for physical cutting tests. The measured energy consumption was 0.0329 J, only 1.32% lower than predicted, demonstrating strong model accuracy. Furthermore, a prototype crushing device was built for performance verification, achieving an average qualified film crushing rate of 89.2%. The findings provide a valuable reference for optimal design of residual film crushers and contribute novel insights into modeling flexible materials like agricultural plastic film.