Objective The aim of this study was to construct a discrete element model of apples and precisely calibrate the corresponding contact parameters.

Method The discrete element model of ‘Luli’ apples was constructed using a spherical particle bonding method, and the optimal particle radius was identified through comparative analysis. A combined method of experimental testing and simulation was adopted to determine the contact parameters, such as the restitution coefficient and friction coefficients. Analysis of variance (ANOVA) was employed to evaluate the effects of collision zone, fruit mass, and foam type on the contact parameters. Various test conditions were simulated to obtain data, which were then used to fit parameter equations. The parameter equations were subsequently verified.

Result The collision zone had no significant effect on the coefficient of restitution. A discrete element model with a 2 mm particle radius was established. The calibrated restitution coefficients, static and rolling friction coefficients between the apple particle models and the super-high and high-density foams were 0.61 and 0.47, 0.46 and 0.61, 0.0166 and 0.0288, respectively. The corresponding values for interactions between apple particle models were 0.65, 0.42 and 0.032 0 respectively. The effectiveness of the calibrated parameters was verified through a bottomless cylinder lifting experiment.

Conclusion The discrete element model of apple is successfully constructed. This study can provide a theoretical basis for the design and optimization of close-range catching mechanisms in apple vibration harvesting or post-harvest processing devices.