深根药材铲式收获部件仿生减阻机理研究

In the process of deep-root medicinal materials harvesting, the harvest components have the problems of high soil adhesion and huge drag resistance. The drag resistance and the soil adhesion could be decreased efficiently by improving the curved surface and their structures. The soil animal Armadillo, which has noticeable soil penetrating and shoveling ability as well as the remarkable anti-soil adhesion characteristics, inspired us to study the drag-reducing mechanisms and design a blade-type harvest components for deep-root medicinal materials. Based on the urgent need to improve the working efficiency in the process of deep-root medicinal materials harvesting, this project utilizes Armadillo as a bionic research object to build the mapping relationship between the structural characteristics of claw and armor, and the effects of anti-soil adhesion and drag-reducing. It is hoped to establish the dynamic model of harvest components - soil interaction, including the claw configurations, armor surface structures, soil characteristics and working resistance, which to guide the design of the blade-type harvest components with simple structures, reliable performances and no-extra energy consumption. The dynamic model of harvest components will be validated according to working resistance experiments and it can offer a reliable influence rule of harvest components - soil interaction. This project provides theoretical and scientific basis for the bionic drag-reducing design of deep-root medicinal materials harvest components. It is valuable to enrich the mechanical soil dynamics theory of harvest component-soil interaction system and solve the practical engineering problems.

深根药材收获过程存在土壤对收获部件粘附量高、工作阻力较大的实际问题，合理设计深根药材收获部件曲面外形及表面结构，可以达到减小土壤粘附、降低工作阻力的效果。土壤动物犰狳快速刺入及铲运土壤的挖掘能力、身不沾土的低粘附特性为深根药材收获部件的减阻设计及机理研究提供了启示。本项目从提高深根药材机械化收获效率的迫切需求出发，采用仿生学研究方法，研究犰狳爪趾、鳞片结构特征与土壤脱附减阻效应之间的映射关系，构建包含外形、结构、土壤特性、工作阻力的收获部件-土壤相互作用的动力学模型，设计形成结构简单、工作可靠和无额外能量消耗的深根药材铲式收获部件，试验验证模型的有效性，系统揭示收获部件-土壤相互作用的仿生减阻机理。本项目为深根药材收获部件的仿生减阻设计提供理论和科学依据，对于拓展并完善收获部件-土壤相互作用的机械土壤动力学理论体系，具有重要的理论价值和工程实际意义。

触土收获部件存在着土壤粘附严重、牵引阻力过大等实际问题，极大降低了收获部件的性能。因此，需要提高收获部件在触土工作过程中刺入、铲运土壤的能力，并减少土壤粘附，以此降低部件切削土壤的工作阻力。经常采用的脱附减阻方法主要有涂敷材料、增加振动等。但这些方法存在着表面耐磨性差、辅助部件多、振动功耗大等问题。土壤动物经过亿万年的进化，表现出优良的土壤挖掘特性和脱附减阻特性，能够有效低阻力。将土壤动物体表特征应用于农业机械触土部件设计，在降低工作阻力方面展现出较好的应用前景。据此，本项目选择穿山甲作为仿生原型，对其鳞片及爪趾开展研究。针对鳞片开展的研究发现，穿山甲鳞片表面具有一定曲率变化，与其他土壤动物相同，呈现出非光滑形态，具有凹槽，呈现扇形分布的纵向棱纹凸起，棱纹大小和间距从中间向两侧递减，呈对称趋势。基于此，开展了仿生超疏水功能表面的研究，利用阳极氧化一步法及激光加工法分别制备了超疏水表面，并对于制备表面进行了形貌及成分测定、耐腐蚀性测定、机械稳定性测试，测试结果表明制备得到的仿生超疏水表面具有具备在强腐蚀环境下的应用条件，以及十分优异的机械稳定性。进一步的抗粘附测试表明，与普通平面相比，超疏水表面降低了土壤的粘附力，有效实现了脱附性能。针对爪趾开展的研究发现，爪趾整体分为内外侧，其中外侧为圆弧面，表面光滑且无特殊构型，内侧具有凸棱特征结构，趾尖呈现圆弧状的楔型结构，因此提供了较优的入土性能，降低了挖掘时的阻力。以爪趾内外侧轮廓及内侧凸棱特征结构设计了仿生挖掘铲，并利用离散元软件EDEM优化了仿生挖掘铲参数，通过3D打印技术加工出仿生挖掘铲后进行了实际土槽试验，结果表明仿生挖掘铲有效降低了挖掘阻力，具有良好的减阻性能。