基于离散元的‘鲁丽’苹果仿真接触参数标定

    Calibration of contact parameters of ‘Luli’ apple for simulation based on discrete element

    • 摘要:
      目的 构建基于离散元法的苹果颗粒模型,并精确标定其仿真接触参数。
      方法 采用球形颗粒组成的方式构建‘鲁丽’苹果离散元模型,通过对比分析确定最合适的球形颗粒半径。采用试验与仿真相结合的方法,确定恢复系数和摩擦系数等接触参数。通过方差分析评估苹果接触部位、果实质量和材料类型对接触参数的影响。调整仿真参数以复现不同试验条件,结合数据拟合得到参数方程,并进行验证。
      结果 苹果的接触部位对其恢复系数的影响不显著。确定了颗粒半径为2 mm的苹果离散元模型,并以此为准,标定了苹果与特高密度和高密度泡棉的恢复系数、静摩擦系数、滚动摩擦系数分别为0.61和0.47、0.46和0.61、0.01660.0288,而苹果相互之间的对应参数分别为0.65、0.42和0.032 0。通过无底圆筒提升试验验证了标定参数的有效性。
      结论 成功构建了苹果离散元模型,研究可为振动收获中接近承接或采后处理装置的设计优化提供理论依据。

       

      Abstract:
      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.

       

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