党参种子的离散元仿真参数标定与试验验证

Calibration and experimental validation of discrete element simulation parameters for Codonopsis pilosula seed

为设计及优化党参机械化播种设备,提供基础仿真参数,本文对甘肃省种植的两种党参种子(渭党1号和甘党2号)通过试验法确定其基本物理参数(形状尺寸、质量密度、体积密度、千粒重、含水率)和接触力学参数(恢复系数、静摩擦系数);通过斜面滚动试验结合EDEM仿真,预测党参种子与ABS塑料板间的滚动摩擦系数;通过调整党参种子模型间的滚动摩擦系数,使仿真形成的种子堆积角逼近种子实际堆积角,预测党参种子间的滚动摩擦系数。结果表明:渭党1号、甘党2号党参种子与ABS塑料板的静摩擦系数分别为0.368和0.341,其种间的静摩擦系数分别为0.389和0.495,与ABS塑料板的碰撞恢复系数分别为0.591和0.518;其种间的碰撞恢复系数分别为0.387和0.346,与ABS塑料板间的滚动摩擦系数分别为0.163和0.168,其种间的滚动摩擦系数分别为0.0153和0.0156。并将得到的仿真参数进行异型窝眼轮排种器试验及验证,仿真与台架试验对比结果显示,两者相对误差为3.16%。表明本试验所建立的离散元模型及基础仿真数据可以用于党参播种机的设计及优化。

This study intended to provide basic simulation parameters for design and optimization of Codonopsis pilosula seed mechanized seeding equipment,including basic physical parameters of shape and size,mass density,bulk density,thousand grain weight and water content and the contact mechanics parameters of recovery coefficient,static friction coefficient for two types of Codonopsis pilosula seed(Weidang 1 and Gandang 2)grown in Gansu Province through experimental methods.The rolling friction coefficient between Codonopsis pilosula seed and ABS plastic plates was predicted by inclined rolling test combining with EDEM simulation.The rolling friction coefficient of Codonopsis pilosula seed was calibrated by adjusting the rolling friction coefficient between Codonopsis pilosula seed to make sure the seed stacking angle formed by the simulation similar to the actual stacking angle.The results showed that the static friction coefficients of Weidang 1 and Gandang 2 Codonopsis pilosula seed and ABS plastic plates were 0.368 and 0.341,respectively,and their interspecies static friction coefficients were 0.389 and 0.495,respectively.The collision recovery coefficients with ABS plastic plates were 0.591 and 0.518,respectively,and their interspecies collision recovery coefficients were 0.387 and 0.346.The rolling friction coefficients with ABS plastics were 0.163 and 0.168,and their interspecies rolling friction coefficients were 0.0153 and 0.0156,respectively.The simulated parameters were tested and verified for the shaped nest-eye wheel seed rower,and the comparison results between simulation and bench test showed that the relative error was 3.16%.The study suggested that the discrete element model and underlying simulation data developed in this experiment could be used for the design and optimization of the Codonopsis pilosula seeder.