冬种马铃薯挖掘及分离部件与高秸秆含量黏湿土壤间的作用机理研究

Straw cover technique is largely applied in winter potato planting in the south, and the harvest time is rainy season. Therefore, the mechanized harvesting process of winter potato is mainly hindered by the great digging resistance due to the intertexture of sticky wet soil and straw as well as the poor separation efficiency for the soil and potato mixture. In order to overcome these defects, the sticky wet soil with high straw content is analyzed, and the mechanical and structural parameters of straw, soil and straw-soil complex are measured. Focusing on the key process of digging and separation, the mechanics and motion characteristics of the sticky wet soil with high straw content are planned to be studied by the following methods. Firstly, the finite element method (FEM) is applied to build the straw-soil complex model in view of contact element between straw and soil, and then the failure mechanism of the straw-soil complex under mechanical actions is analyzed. Secondly, the discrete element method (DEM) is adopted for build the sticky wet soil model, and the anti-adhesion mechanism of the sticky wet soil under mechanical actions is analyzed. According to the above study, double-vibration drag reduction digger can be designed. Furthermore, the structure and movement parameters are optimized by dynamic and movement analyzing. Finally, field experiments were carried out for the performance test of all the components. The research result would be of great significance in the development of the mechanized harvesting process of winter potato under the condition of the sticky wet soil with high straw content, and it can provide scientific bases for the design of harvesting machinery for the winter potato.

南方冬种马铃薯大量采用秸秆覆盖栽培技术，且在雨季收获，秸秆与黏湿土壤交织在一起，导致传统马铃薯收获机在使用中遇到挖掘阻力大，薯土分离率低的问题。本项目以高秸秆含量黏湿土体为研究对象，测定秸秆、土壤及“秸秆-黏湿土壤”复合体的力学参数与结构参数，围绕挖掘与分离关键作业环节，采用有限元法构建加入秸秆与土壤接触单元的“秸秆-黏湿土壤”复合体模型，开展复合体在机械作用下的破坏机理研究；采用离散元法构建引入液桥力与粘附力的黏湿土壤模型，进行黏湿土壤在机械作用下的减粘脱附机理研究，揭示高秸秆含量黏湿土体在机械作用下的力学表征与运动规律，设计双重振动减阻挖掘部件，并进行部件运动学与动力学分析，优化部件结构与运动参数，进行田间试验测试。项目的研究成果将为冬种马铃薯及其他根茎类作物收获机械的研发提供科学依据，对于解决高秸秆含量黏湿土壤条件下冬种马铃薯机械化收获难题具有重要意义。

我国南方冬种马铃薯普遍采用稻草秸秆覆盖种植工艺，且收获期正值雨季，大量秸秆与黏湿土壤交织在一起，给机械化收获带来困难，其中挖掘阻力大的问题较为突出，亟需进行高秸秆含量黏湿土壤条件下的减阻挖掘工作机理研究。本项目以高秸秆含量黏湿土壤为研究对象，以减阻挖掘为目标，主要开展了以下研究工作：. 1、基于冬种马铃薯的种植工艺和农艺要求，研究了冬种马铃薯生长特性和相关物料特性，为收获机挖掘宽度和挖掘深度的确定以及马铃薯收获过程中碰撞与作用研究提供了依据。2、通过试验得到了秸秆、土壤及“秸秆-黏湿土壤”复合体的力学参数与结构参数，采用有限元法构建了“秸秆-黏湿土壤”复合体仿真模型，开展了复合体在机械作用下的破坏仿真分析，获得了复合体在外力作用下的形态与力学变化规律。3、引入考虑了湿颗粒间粘结力的JKR接触模型，构建了黏湿土壤离散元模型，利用堆积角试验结合GEMM数据库进行了离散元模型参数标定，获得了黏湿土壤离散元模型仿真参数。利用该土壤参数进行了挖掘铲在黏湿土壤中的运动仿真分析，得到了平动与振动下的挖掘阻力，仿真结果表明，振动挖掘阻力较平动挖掘阻力减少了25%。4、设计了振动挖掘阻力测试试验台，利用该试验台进行了挖掘铲振动与平动阻力测试，试验证明振动挖掘阻力较平动挖掘阻力减少了23%。5、研制了一种覆草冬种马铃薯收获机并进行了薯草分离效果的田间试验，设计了一种冬种马铃薯振动挖掘收获机，为样机生产奠定了基础。. 本项目研究为冬种马铃薯及其他根茎类作物收获机械的减阻挖掘部件研发提供了科学依据，对于解决高秸秆含量黏湿土壤条件下的冬种马铃薯收获技术难题具有重要意义。