Research on Rice Grain Collision Fracture Behavior With Experimental and Cohesive Zone Model

ABSTRACT During rice processing, collision is a main interaction lowering economic benefit for grain broken, leading to the crucial role of grain collision fracture control. In this study, a self‐established collision test platform combined with in situ high‐speed imaging is built. Effects of collision velocity (12.56–69.08 m/s) and rice variety (indica, japonica, glutinous) on rice damage and crack propagation are researched. The grain fracture morphology and behavior were in‐depth analyzed. A rice grain cohesive zone model (CZM) is built, and the collision behavior is simulated with finite element modeling (FEM). Results revealed four collision damage stages: no damage (Stage A, < 18.84 m/s), micro‐cracking (Stage B, 18.84–37.68 m/s), macro‐cracking (Stage C, 37.68–50.24 m/s), and fragmentation (Stage D, > 50.24 m/s). Rice type leads to different crack patterns, with indica rice showing T‐shape crack and glutinous rice Y‐shape crack. Using 3D microscopy to observe “cross‐coupled” crack networks originating from collision points. Primary cracks propagate along the short axis, with secondary cracks branching at angles to the long axis. Rice crack FEM simulation showed that the brown rice modeling crack forming and fracture match with experiment testing. Stress concentration exists in the contact center zone, and a main transverse crack formed. Peak collision force increased with increasing velocity. The research provides theoretical support for rice processing optimization and machine design.