| 荸荠离散元仿真参数标定与试验 |
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| 引用本文： | 张国忠,陈立明,刘浩蓬,董昭,张清洪,周勇.荸荠离散元仿真参数标定与试验[J].农业工程学报,2022,38(11):41-50. |
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| 作者姓名： | 张国忠 陈立明 刘浩蓬 董昭 张清洪 周勇 |
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| 作者单位： | 1. 华中农业大学工学院，武汉 430070； 2. 农业农村部长江中下游农业装备重点实验室，武汉 430070 |
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| 基金项目： | 国家特色蔬菜产业技术体系专项（CARS-24-D-02）；湖北省高等学校优秀中青年科技创新团队计划项目（T201934） |
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| 摘 要： | 针对荸荠深加工中机械去皮、切块等技术与装备研发缺乏离散元仿真模型与参数、难以通过仿真指导装置设计与优化的问题，该研究开展了荸荠的离散元参数标定与试验研究。借助三维扫描逆向建模技术获得荸荠轮廓，通过物理试验测得其本征参数和基本接触参数，通过质构仪测得刀片对荸荠的最大剪切力为67.2 N。应用Hertz-Mindlin with bonding模型对荸荠进行建模，以最大剪切力为评价指标，对粘结参数进行虚拟标定试验，采用二水平析因试验和最陡爬坡试验筛选显著性因素，通过响应面法设计试验和优化求解，并进行仿真验证。结果显示，仿真值和实测最大剪切力相对误差为0.89%。进行不同刀片的剪切试验，结果表明，仿真值与实测最大剪切力相对误差不高于7.41%。研究结果表明，该研究所建荸荠模型与参数标定结果可用于离散元仿真研究，对荸荠去皮、切块加工装置设计具有指导意义。
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| 关 键 词： | 离散元 剪切 荸荠 参数标定 粘结模型 |
| 收稿时间： | 2022/2/15 0:00:00 |
| 修稿时间： | 2022/5/28 0:00:00 |
Calibration and experiments of the discrete element simulation parameters for water chestnut |
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| Zhang Guozhong,Chen Liming,Liu Haopeng,Dong Zhao,Zhang Qinghong,Zhou Yong.Calibration and experiments of the discrete element simulation parameters for water chestnut[J].Transactions of the Chinese Society of Agricultural Engineering,2022,38(11):41-50. |
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| Authors: | Zhang Guozhong Chen Liming Liu Haopeng Dong Zhao Zhang Qinghong Zhou Yong |
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| Institution: | 1. College of Engineering, Huazhong Agricultural University, Wuhan 430070, China; 2. Key Laboratory of Agricultural Equipment in Mid-lower Yangtze River, Ministry of Agriculture and Rural Affairs, Wuhan 430070, China |
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| Abstract: | Water chestnut has been one of the most important aquatic vegetables in Asian countries. Annual production of more than 800 000 tons can be found in the south of the Yangtze River Valley. The edible flesh of the water chestnut is the crisp and tasty bulbous underground with a smooth reddish-brown surface. However, the current deep-processing of the water chestnut completely depends on manual work. The water chestnut industry has been severely limited to labor-intensive, high-cost, and small-scale production at present. It is very necessary to develop the agricultural machinery for the large-scale production of water chestnuts. Fortunately, discrete element simulation (DEM) can be widely used for the optimal design of mechanized progress. In this study, a DEM model was established to determine the key parameters in the peeling and slicing process of water chestnut using the calibration of EDEM software. A series of virtual calibration experiments were conducted to obtain the accurate shape of fresh water chestnut using 3D scanning reverse modeling. The physical tests were carried out for the geometric size of the water chestnut, the parameters of mechanical properties (density, Poisson''s ratio, modulus of elasticity), and the basic contact parameters (coefficient of collision recovery, coefficient of static friction, and coefficient of dynamic friction) between a water chestnut and stainless steel. The shear test showed that the average of the maximum force of the blade on water chestnut measured by texture analyzer was 67.2 N, taking as the reference of the virtual calibration experiment. A Hertz-mindlin with the bonding model was established for the water chestnut in EDEM software. A virtual calibration experiment was designed with the shear stress of water chestnut as the evaluation index. A single factor test was used to determine the influence range of each factor, including the particle contact radius, normal stiffness per unit area, shear stiffness per unit area, critical normal stress, critical shear stress, and bonded disk radius. Among them, the normal stiffness per unit area, shear stiffness per unit area, and bonded disk radius were selected as the significant factors after the two-level test. The steepest climb test combined with the response surface (Box-Behnken Design) test was utilized to further reduce the range of the significant parameters. The optimized results demonstrated that the total model decision coefficient R2 of quadratic regression was 0.992 2, indicating a better fitting performance. An optimum combination of parameters was obtained with the objective of the minimum shear force: the normal stiffness per unit area was 1.185×108 N/m3, the shear stiffness per unit area was 9.091×107 N/m3, and the bonded disk radius was 1.655 mm (the rest of the other non-significant factors was the median), the particle contact radius was 1.6 mm, the critical normal stress was 10.0×106 Pa, and the critical shear stress was 10.0×106 Pa. The optimized parameters were simulated to verify by the field measurement, where the relative error between the simulated value and the measured maximum shearing force was 0.89%, indicating the correct model and reliable calibration parameters. Different blade curves were also used in the EDEM software and texturing instrument, in order to verify the generality of water chestnut modeling. The relative error between simulation and measured values was not more than 7.41%. The more stable stress curve of the convex blade without the sudden change of force can be expected to prolong the serving life of the blade. The convex edge can greatly contribute to reducing the maximum force in the process of water chestnut cutting. The finding can provide a strong reference for the design of various devices during water chestnut production. |
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| Keywords: | discrete element shear water chestnut parameter calibration bonding model |
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