| 马铃薯种薯机械排种离散元仿真模型参数确定及验证 |
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| 引用本文： | 石林榕,孙伟,赵武云,杨小平,冯斌.马铃薯种薯机械排种离散元仿真模型参数确定及验证[J].农业工程学报,2018,34(6):35-42. |
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| 作者姓名： | 石林榕 孙伟 赵武云 杨小平 冯斌 |
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| 作者单位： | 1. 甘肃农业大学机电工程学院，兰州 730070；,1. 甘肃农业大学机电工程学院，兰州 730070；,1. 甘肃农业大学机电工程学院，兰州 730070；,1. 甘肃农业大学机电工程学院，兰州 730070；,2. 甘肃农业大学机农学院，兰州 730070 |
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| 基金项目： | 国家自然科学基金资助项目（51665002）；公益性行业（农业）科研专项（201503105）；甘肃省高等学校科研项目(2016B-039)；甘肃农业大学盛彤笙科技创新基金（GSAU-SLS-1623、GSAU-STS-1624） |
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| 摘 要： | 为方便利用离散单元法优化勺链式马铃薯排种装置的排种性能,该文通过试验、参考文献测定和计算了马铃薯基本物理参数(密度、弹性模量、泊松比和恢复系数);利用自制的马铃薯静摩擦系数测定装置测定了种薯间、种薯与钢板、种薯与塑料之间的静摩擦系数分别为0.452、0.445和0.517;通过斜面法测定种薯与钢板、塑料的动摩擦系数分别为0.269、0.303。由于通过颗粒堆积法建立的种薯在外形尺寸和质心上与实际薯有一定误差,因此,以种薯堆积角为目标值,通过改变仿真种薯模型的动摩擦系数建立回归模型,预测的种薯间动摩擦系数为0.024;为检验所确定种薯仿真模型参数的可靠性,通过切片造型法构建马铃薯种薯(球形、椭球、不规则)模型,采用确定的参数进行马铃薯堆积角仿真试验,并与试验堆积角进行了对比,结果表明马铃薯仿真与试验堆积角相对误差为1.33%;以勺链式马铃薯排种装置为研究对象,对比仿真和台架试验排种性能指标结果表明,马铃薯仿真与试验相对误差为9.16%,空种率相对误差为6.20%,其相对误差均小于10%;仿真与试验重播率、空种率满足GB/T 6242-2006《种植机械马铃薯种植机试验方法》技术要求。
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| 关 键 词： | 农业机械 农作物 计算机仿真 马铃薯 离散单元法 参数 验证 |
| 收稿时间： | 2017/8/23 0:00:00 |
| 修稿时间： | 2018/1/30 0:00:00 |
Parameter determination and validation of discrete element model of seed potato mechanical seeding |
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| Shi Linrong,Sun Wei,Zhao Wuyun,Yang Xiaoping and Feng Bin.Parameter determination and validation of discrete element model of seed potato mechanical seeding[J].Transactions of the Chinese Society of Agricultural Engineering,2018,34(6):35-42. |
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| Authors: | Shi Linrong Sun Wei Zhao Wuyun Yang Xiaoping and Feng Bin |
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| Institution: | 1. School of Mechanical and Electrical Engineering, Gansu Agricultural University, Lanzhou 730070, China;,1. School of Mechanical and Electrical Engineering, Gansu Agricultural University, Lanzhou 730070, China;,1. School of Mechanical and Electrical Engineering, Gansu Agricultural University, Lanzhou 730070, China;,1. School of Mechanical and Electrical Engineering, Gansu Agricultural University, Lanzhou 730070, China; and 2. College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China |
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| Abstract: | Abstract: For optimizing the seed metering performance of the seed metering device for potato with the help of discrete element method, firstly the basic physical parameters of seed potato (density, elastic modulus, Poisson''s ratio and coefficient of restitution) were obtained through the experiment and from the references. From references we know that coefficient between seed potato and potato, steel, plastic is 0.79, 0.71 and 0.66 respectively. From experimental results the average density of seed potato is 1 048 kg/m3 by the method of drainage, and the average moisture content of seed potato was 80.15% by drying method, and the volume density is 631.88 kg/m3. Using the self-made measuring apparatus of potato static friction coefficient, the static friction coefficients between potato and matierial including potato, plastic and steel were measured, and these were respectively 0.452, 0.445 and 0.517. By the inclined plane method, the dynamic friction coefficients between potato and other matierial including steel and plastic were determinated, and these were respectively 0.269 and 0.303. The shape, size and center of mass of the patotoes through the particle repose method had a certain error with that of the actual potatoes, therefore, taking the actual potato repose angle as the target value, and changing the dynamic friction coefficient, the simulation regression model of predicting dynamic friction coefficient of potato was establised. Predicted value of dynamic friction coefficient is 0.024 when potato stacking angle is 24.39°. For verifying the reliability of parameters of potato simulation model. Selection of seed potato which were close to the 3 types of statistical mean values were modeled respectively. The modeling process is as follows: the largest potato contour along the XY section is cut, and which was connected the section to the white paper, and draw the outline with pencil, and then trace the potato along the YZ cross section. The image is collected vertically to the tape of the sheet. The image was put into AutoCAD using the spline curve command will outline the stroke of potato, potato slices one by one in the order from the top into the datum on the corresponding. The outline of the whole potato is introduced into Solidworks and the potato is built with a lofting order. The parameters of simulation model were used to simulate the potato repose angle, which was then compared with the experimental potato repose angle of outer contour. The length and height of repose angle bottom edge in simulation and experiment are compared and they are 436 and 99 mm respectively, and their repose areas are basically the same. The repose angle in simulation and experiment is 24.72° and 24.39° respectively, and their relative error is 1.33%. It can be seen that the simulation and experimental repose angle are basically the same. Therefore, from the above comparison results, it is known that the simulated and experimental repose angle are basically the same. Moreover, spoon-chain seed potatoes metering device is used to validate the parameters of the potato repose angle simulation, and the replay rates in simulation and experiment are 11.90% and 13.10% respectively, and their relative error is 9.16%; the empty hole rates in simulation and test are 8.93% and 9.52% respectively, and their relative error is 6.20%, which satisfies the GB/T 6242-2006 Test method for potato planting machine in planting machinery. Comparison between simulation and experimental results shows that under the bench experiment condition, compared with the simulation results, the empty hole rate of the potato metering device increased by 0.59%, and the replay rate decreased by 1.2%. According to the analysis, it is due to the influence of the increase of the variation coefficient of the seed potato''s size. |
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| Keywords: | agriculture machinery crops computer simulation potato discrete element method parameters verification |
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