半夏块茎离散元参数标定与试验验证

Calibration and experimental verification of discrete element parameters of Pinellia ternata tuber

针对半夏块茎收获、加工等机械化作业过程采用离散元法仿真分析时,半夏块茎本征参数和接触参数缺乏等问题,以旱半夏块茎为研究对象,分别测定其三轴尺寸、含水率、密度、泊松比、弹性模量和剪切模量等本征参数;通过碰撞弹跳试验和斜面滑移试验测定半夏块茎与钢板之间碰撞恢复系数和静摩擦因数;根据块茎特征创建离散元模型,通过斜面滚动试验和EDEM仿真标定半夏块茎与钢板之间的滚动摩擦因数;以半夏块茎堆积角平均值为响应值,基于二次回归正交旋转组合试验的响应面优化法,确定半夏块茎间碰撞恢复系数、静摩擦因数和滚动摩擦因数的较优参数组合。结果表明:半夏块茎的三轴尺寸基本呈正态分布规律,尺寸值在4.03~26.68 mm之间,密度为1012.68 kg·m^(-3),湿基含水率为45.54%,泊松比为0.416,弹性模量平均值为35.93 MPa,剪切模量平均值为15.68 MPa;半夏块茎与钢板之间碰撞恢复系数、静摩擦因数和滚动摩擦因数分别为0.509、0.349和0.0735;半夏块茎间碰撞恢复系数、静摩擦因数和滚动摩擦因数分别为0.587、0.453和0.086。应用所得参数进行侧壁坍塌验证试验,验证试验结果表明,仿真休止角为23.19°,物理试验休止角为22.56°,休止角相对误差为2.79%,表明研究所建立的半夏块茎离散元模型和基础参数可用于半夏块茎相关离散元仿真研究。

To solve the problem with lack of intrinsic parameters and contact parameters of Pinellia ternata tuber during harvesting and processing of Pinellia ternata tuber simulation and analysis using the discrete element method,this study took the dry Pinellia ternata tuber as the research object,and measured the intrinsic parameters such as triaxial size,moisture content,density,Poisson’s ratio,elastic modulus and shear modulus.The impact recovery coefficient and static friction coefficient between Pinellia ternata tuber and steel plate were measured by impact bounce test and inclined plane sliding test.The discrete element model was established according to the tuber characteristics,and the rolling friction coefficient between Pinellia ternata tuber and steel plate was calibrated by inclined rolling test and EDEM simulation.Taking the average stacking angle of Pinellia ternata tuber as the response value and based on the response surface optimization method of quadratic regression orthogonal rotation combination test,the optimal parameter combination of collision recovery coefficient,static friction coefficient and rolling friction coefficient between Pinellia ternata tubers was determined.The results showed that the triaxial size of Pinellia ternata tuber was basically normal distribution.The size value was 4.03~26.68 mm.The density was 1012.68 kg·m^(-3).The moisture content of wet basis was 45.54%.The Poisson’s ratio was 0.416.The average value of elastic modulus was 35.93 MPa,and the average value of shear modulus was 15.68 MPa.The collision recovery coefficient,static friction coefficient and rolling friction coefficient between Pinellia ternata tuber and steel plate were 0.509,0.349 and 0.0735 respectively.The collision recovery coefficient,static friction coefficient and rolling friction coefficient between tubers of Pinellia ternata tuber were 0.587,0.453 and 0.086,respectively.The parameters obtained were applied to the side wall collapse verification test.The verification test results showed that the simulation repose angle was 23.19°,the physical test repose angle was 22.56°,and the relative error of repose angle was 2.79%.The discrete element model of Pinellia ternata tuber and the basic parameters of contact parameters established by the study can be used for the simulation study of Pinellia ternata tuber related discrete element.