Research on establishment of bonded particle model for pellet feed and its application

This study develops and validates a bonded particle model to investigate impact-induced breakage of piglet pellet feed using the discrete element method. To address the lack of reliable DEM parameters for pellet attrition, bonding properties were calibrated through uniaxial compression experiments combined with numerical simulations and response surface optimization. The calibrated parameters include a normal stiffness per unit area of 2.00e10 N/m3, a tangential stiffness per unit area of 7.41e9 N/m3, and bond strengths of 500 MPa. The validated model was applied to simulate pellet motion and fragmentation in a centrifugal impact device. The breakage rate increased monotonically with impeller speed from 500 to 1500 rpm, reaching 21.43% at the highest speed, in good agreement with experimental results. A strong linear correlation (R2 = 0.9970) between simulated bond breakage fraction and experimentally measured mass-based breakage rate confirms that bond failure percentage provides a physically meaningful descriptor of macroscopic fragmentation. In addition, breakage exhibited a non-linear dependence on impact angle, with a maximum value of 6.86% at 75° due to the combined axial and radial loading effects. The proposed framework can provide theoretical guidance for improving pellet durability and optimizing processing conditions.