郝建军, 魏文波, 黄鹏程, 秦家辉, 赵建国. 油葵籽粒离散元参数标定与试验验证[J]. 农业工程学报, 2021, 37(12): 36-44. DOI: 10.11975/j.issn.1002-6819.2021.12.005
    引用本文: 郝建军, 魏文波, 黄鹏程, 秦家辉, 赵建国. 油葵籽粒离散元参数标定与试验验证[J]. 农业工程学报, 2021, 37(12): 36-44. DOI: 10.11975/j.issn.1002-6819.2021.12.005
    Hao Jianjun, Wei Wenbo, Huang Pengcheng, Qin Jiahui, Zhao Jianguo. Calibration and experimental verification of discrete element parameters of oil sunflower seeds[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2021, 37(12): 36-44. DOI: 10.11975/j.issn.1002-6819.2021.12.005
    Citation: Hao Jianjun, Wei Wenbo, Huang Pengcheng, Qin Jiahui, Zhao Jianguo. Calibration and experimental verification of discrete element parameters of oil sunflower seeds[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2021, 37(12): 36-44. DOI: 10.11975/j.issn.1002-6819.2021.12.005

    油葵籽粒离散元参数标定与试验验证

    Calibration and experimental verification of discrete element parameters of oil sunflower seeds

    • 摘要: 针对采用离散元法对油葵播种、收获等关键工作过程仿真分析时,油葵籽粒本征参数、油葵籽粒与油葵机械化种植及收获装备间接触参数缺乏问题,该研究以油葵籽粒为研究对象,利用三维扫描逆向建模技术与EDEM软件建立油葵籽粒离散元模型,通过物理试验与虚拟仿真试验对仿真参数进行标定。采用绝对原点数显卡尺、电子分析天平、万能材料拉压力试验机等测定了矮大头567油葵籽粒的三维几何尺寸、密度、含水率、泊松比、弹性模量、剪切模量和静摩擦系数;采用圆筒提升法进行油葵籽粒物理堆积试验,利用MATLAB对堆积图像进行处理获得物理堆积试验油葵籽粒的堆积角为48.858°。以堆积角为评价指标,利用Plackett-Burman试验、最陡爬坡试验筛选出对堆积角影响显著的因子及取值范围;通过响应面寻优试验结果的方差分析和寻优计算,确定了油葵籽粒间静摩擦系数与动摩擦系数的较优组合为0.41、0.05。以较优参数组合进行仿真堆积试验,测得堆积角为48.976°,与物理堆积试验得到的堆积角误差为0.24%;进行电磁料斗振动物理试验与仿真试验对标定结果进行验证,得到不同工作电压下油葵籽粒物理试验与仿真试验的质量流率曲线,2条曲线相关系数为0.998,变化趋势基本一致。研究结果表明,油葵籽粒模型和标定所得的离散元仿真参数具有可靠性,可为油葵籽粒离散元仿真研究提供参考。

       

      Abstract: Abstract: Discrete element method (DEM) is widely used to simulate the key work process of oil sunflower seeding and harvesting. However, feature parameters of oil sunflower seeds are still lacking, particularly on the contact parameters between seeds and mechanized planting/harvesting equipment. Taking the oil sunflower seeds as the research object, this research aims to establish a discrete element model using a 3D scanning reverse simulation in the EDEM software, and then to calibrate the specific parameters of oil sunflower seeds. The average length, width, and thickness of 567DW oil sunflower seeds were 13.36, 6.94, and 4.63 mm, respectively, in an absolute digital caliper. The weight of 100 567DW oil sunflower seeds was measured at 9.547 g using an electronic analytical balance. The density of 567DW oil sunflower seeds was 849.4 kg/m3, and the water content was 10.13% in a B0D-75-Ⅱ electric thermostatic drier and pycnometer. Poisson's ratio, elastic modulus, and shear modulus of oil sunflower seeds were 0.413, 304.69, and 107.82 MPa, respectively. A universal tensile testing machine was also used. The static friction coefficients between oil sunflower seeds and steel plate/plexiglass were 0.423 and 0.525 on the inclined plane, respectively. A physical stacking test was performed on a cylinder lifting for the oil sunflower seeds. MATLAB platform was selected to carry out a gray-scale and binarization processing on the image of stacking angle. Bwperim and imfill functions were selected to extract the outline of binary image, and then perform the holes filling and expansion on the inner edge, finally to obtain the edge contour. The edge contour was imported into the Origin software, where the converted coordinate data was obtained for the linear fitting slope, thereby obtaining a stacking angle of 48.858°. Taking the stacking angle as the evaluation index, the Plackett-Burman test was used to screen out the factors with a significant impact on the stacking angle and the static and dynamic friction coefficients between the oil sunflower seeds. The steepest ascending path was used to determine the range of factors with a significant impact on the stacking angle. The variance analysis was also made to optimize the response surface. Optimal static/dynamic friction coefficients between oil sunflower seeds were determined to be 0.41 and 0.05, respectively. A stacking test was simulated with a better parameter combination, where the measured stacking angle was 48.976°, only 0.24% in error with the stacking angle, compared with the physical stacking test. The electromagnetic hopper vibration and simulation were carried out to obtain the mass flow rate curves of oil sunflower seeds under different working voltages. The correlation coefficient of the two curves was 0.998, indicating the changing trend was all the same. Consequently, the reliable model of oil sunflower seeds and the calibrated discrete element parameters can provide significant theoretical support to the discrete element simulation.

       

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