鲜莲籽离散元仿真参数标定

    Parameters calibration of discrete element simulation for fresh lotus seeds

    • 摘要:
      目的  确定鲜莲籽机械化加工过程中离散元仿真模型参数,为鲜莲籽机械化加工仿真试验提供数据参考。
      方法  本研究利用EDEM仿真软件开展鲜莲籽离散元仿真参数标定。以产自湖北洪湖的‘太空莲36号’为试验对象,通过落种试验测定鲜莲籽实际落种的堆积角和休止角。基于Hertz-Mindlin (no slip)接触模型进行鲜莲籽落种仿真试验,以鲜莲籽堆积角和休止角的实测值与仿真值之间的误差为试验指标,通过Plackett-Burman试验确定对堆积角和休止角影响显著的接触参数,通过最陡爬坡试验确定鲜莲籽离散元模型最优接触参数组合。采用料斗进行实际落种验证试验,以莲籽落种速率为试验指标,对比实际与仿真落种验证试验莲籽落种速率,验证最优参数组合可靠性。
      结果  莲籽间静摩擦系数、莲籽间滚动摩擦系数对堆积角影响极显著(P<0.01);莲籽间滚动摩擦系数对休止角影响极显著(P<0.01),莲籽间静摩擦系数、莲籽−有机玻璃静摩擦系数对休止角影响显著(P<0.05)。最优接触参数组合为莲籽间静摩擦系数0.4、莲籽间滚动摩擦系数0.02、莲籽−有机玻璃静摩擦系数0.4。落料验证试验结果表明,实际试验与仿真试验的鲜莲籽落种速率最大相对误差不超过3.65%。
      结论  标定的鲜莲籽离散元仿真模型接触参数准确可靠,研究结果可为莲籽加工机械的结构优化设计提供数据参考。

       

      Abstract:
      Objective  To determine the parameters of discrete element simulation model in the mechanized processing of fresh lotus seeds, and provide data references for the mechanized processing simulation test of fresh lotus seeds.
      Method  The calibration of discrete element simulation parameters of fresh lotus seeds was carried out by EDEM simulation software. The accumulation angle and repose angle of the actual fresh lotus seeds were measured by seed drop test with ‘Space lotus 36’ from Honghu, Hubei. Based on the Hertz-Mindlin (no slip) contact model, a simulation test of fresh lotus seed drop was conducted, and the error between the measured and simulated values of fresh lotus seed accumulation angle and repose angle was used as the test index to determine the contact parameters with significant effects on accumulation angle and repose angle through the Plackett-Burman test. The steepest climb test was conducted to determine the optimal contact parameter combinations in discrete element model for fresh lotus seeds. The actual seed drop verification test was carried out using the hopper with seed drop rate as the test index. The seed drop rates in actual and simulated seed drop verification tests were compared to verify the reliability of the optimal parameter combination.
      Result  The effects of static friction coefficient between lotus seeds and rolling friction coefficient between lotus seeds on the accumulation angle were highly significant (P<0.01); The effects of rolling friction coefficient between lotus seeds on the repose angle were highly significant (P<0.01), and the effects of static friction coefficient between lotus seeds and static friction coefficient between lotus seeds and plexiglass on the repose angle were significant (P<0.05). The optimal combination of contact parameters was 0.4 for static friction coefficient between lotus seeds, 0.02 for rolling friction coefficient between lotus seeds, and 0.4 for static friction coefficient between lotus seeds and plexiglass. The results of the drop verification test showed that the maximum relative error of fresh lotus seed drop rate between the actual test and the simulation test was not exceeding 3.65%.
      Conclusion  The contact parameters of the calibrated discrete element simulation model for fresh lotus seeds are accurate and reliable, and the findings can provide data references for the structural design optimization of lotus seed processing machinery.

       

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