基于鲜食青大豆株系―螺旋梳刷脱荚机构交互作用的连续收获机理及低损伤优化

In the recent years, with green beans planting area increasing year by year,mechanical harvest will become an inevitable trend. The existing technology makes the leakage rate, breakage rate and impurity rate too high, which severely hampers its mechanization harvest. Setting the typical varieties of green beans and spiral threshing device as object, the strain biological properties and mechanical properties are needed to be determined. The flexible model of green soybeans can be constructed by comprehensive applicating of UG parametric modeling, as well as ANSYS, ADAMS, EDEM, etc. multi body dynamics and discrete element theory and method. On the basis of Hertz contact mechanics and analyzing of the collision between particles using elastic theory, the collision model of threshing process will be established by the principle of conservation of energy.Researching on sensing technology and control algorithm is to construct the.rigid-flexible coupling dynamic system so as to simulate the operation process.The impact mechanism and improvement measures of work quality are needed to be explored by combining high speed photography analysis and quality index measurement. Applying kinds of research methods including multi-objective simulation optimization, multi-factor response surface experimental optimization,threshing quality optimization base on satisfactory theory and experimental verification, the comprehensive optimization design method of green soybean semi-feeding picking device is to be explored and the simulation optimization model of device design and the prediction model of operation.qualities can be established, therefore the optimal combination of structural parameters and operating parameters will be achieved finally. This study will provide a theoretical basis and new methods for the research and development of green beans and other fruit crops harvesters.

近年，鲜食青大豆种植面积逐年攀升，机械化采收成必然趋势。现有技术脱荚漏采率、破损率、含杂率过高，严重阻碍其机械化收获。以青大豆株系―螺旋梳刷脱荚机构为对象，测定其株系生物性状、机械力学特性；应用UG参数化建模，ANSYS、ADAMS、EDEM多体动力学与离散元理论和方法，构建其株系柔性颗粒模型；以Hertz接触力学为基础，采用弹性理论方法分析颗粒间的碰撞问题，通过能量守恒原理建立脱荚过程的碰撞模型；研究仿真检测传感技术和控制算法，构建青大豆株系-脱荚装置刚柔耦合动力学仿真系统及作业过程动力学仿真；高速摄影分析及质量指标测定等相结合，探索作业质量影响机理与提升途径；多目标仿真、多因素响应面试验，脱荚质量满意度优化及试验验证，探索青大豆脱荚装置综合优化设计方法，构建仿真优化设计模型和作业质量预测模型，实现结构和工作参数最佳组合。其成果能为碗豆等其它结荚豆类作物收获技术提供理论基础。

1.重点以鲜食青大豆“萧农秋艳”、“豆通六号”为试验对象，测定青大豆植株各部位含水率；重点进行了鲜食青大豆茎秆及荚柄抗拉强度力学性能测试，青大豆茎秆及豆荚压缩力学性能测试；径向拉伸试验测试获取了青大豆茎秆的应力－应变、受力－位移曲线。.2.通过赫兹应力建立荚果、籽粒挤压方程及F与之间函数关系，即综合弹性常数C及荚果、籽粒弹性模量之间关系。试验测定得到青毛豆籽粒、荚壳、荚果各部分的弹性模量及籽粒泊松比；先后对萧农秋艳与豆通六号进行籽粒B型、L型受压及荚果B型受压力学测试，其籽粒B型、L型与荚果B型破裂力、弹性模量和最大变形分别为 72.2～115.2N、139.2～160.2N，11.7～15.55Mpa、16.05～19.1Mpa，2.34～3.26mm、2.51～2.93mm；139.2～160.2N、16.05～19.1Mpa，2.51～2.93mm，并观察得到青毛豆荚果受压的破损特征。通过有限元分析法模拟青毛豆荚果B型、籽粒B型与L型的力－变形曲线，和试验曲线比较，三者较为一致，其相关系数均达到 0.91以上；运用有限元分析软件workbench对青毛豆荚果B型150N受压、籽粒B型100N受压、籽粒L型50N受压力学性能进行分析。.3.针对前悬挂梳刷脱荚滚筒，设计了滚筒参数和滚筒梳齿排列，分析了梳刷脱荚受力过程。以脱荚率、豆荚破损率为响应指标，滚筒转速、机器前进速度、梳齿距离为影响因素，通过Design-Expert软件进行了三因素五水平正交旋转中心组合试验分析。通过方差分析、显著因素对响应指标的影响分析及影响因素与评价指标的数学回归模型等方式，确定了最优参数组合为：梳齿转速397.36 r/min，梳齿轴向最小间距 4.8mm，机具前进速度 0.5m/s。田间试验结果表明：在优化参数组合下，该机收获效率˃0.187hm2/h，脱荚率˃90%，破损率<4.5%，含杂率<7.8%。.4.通过EDEM摸拟收获机实际收获作业工况中组合因素对比分析，分析不同时刻豆荚颗粒分布图、脱落数量随时间变化曲线图、颗粒受力分布曲线、颗粒速度云图等。为整机脱荚滚筒设计与定型提供了科学指导意义，为鲜食青大豆脱荚过程分析和鲜食青大豆收获机的优化设计建立了一种新方法。