平板式触土工作部件与扰动饱和水田土壤间接触-流变-阻力耦合机制研究

In order to provide an appropriate growth environment for the rice seed or the seedlings in paddy field,soil was plowed and raked flat which structure was disturbed，liquidity was enhanced and strength was degraded .These changes increased the mechanical movement resistance and reduced the dynamic performance of mechanical, limited to upgrade the rice planting mechanization level in China..It is an arduous and important research topic to study the coupling contract between the working assembly on soil and paddy soil for impriving the transit ability of furrowing and planting and seeding machine in disturbed paddy soil. For optimizing its ability,the soil’s flowing and the stress,shear,adhesion force, subsidence ,fluent between the soil working assembly and paddy soil should be analysised.The soil working assembly include the flat board of the boat-tractor ,the flat board of the seeder and the wheel(such as the impeller).To study the rheological properties of the saturated paddy soil disturbance, and the coupling dynamics characteristic between direct rice seeder dragged by boat-tractor and rheological mechanics of disturbed paddy soil, many methods will be used which included field and soil bin test, theoretical analysis, virtual simulation and finite element analysis, and many rules will be tried to illustrate which include the flow rule of disturbance soil,ground pressure distribution rule under the boat-tractor ,the contact surface forming conditions of reduction viscosity and drag resistance between the soil and the boat-tractor , the drive characteristics of wheel and the Contact-Rheology-Resistance coupling mechanism between the working assembly and disturbed paddy soil . The transit resistance,toque and power of the boat-tractor will be evaluated which are influenced by the shape,surface features,structure and motion parameters of the working assembly. Based on the research the technical targets will be gotten which include controlling the mud’s flow way on the soil surface , reducing the moving resistance, improving the efficiency and getting the morphology, kinematics, dynamics optimization results of the seeder. The research results could be used to analysis the paddy soil mechanics characteristics, to optimize the machine dynamic performance in paddy soil , to improve the design of rice planting machinery , to contribute theoretical research as well as practical reference under the complicated.environment of agricultural machinery.This study belongs to the basic theory of paddy soil ground machine system field, which has obvious forward-looking, significance important theoretical and practical application value.

耕层土壤经浸泡耕整旋耙后，形成松软粘稠、泥水混合的扰动饱和含水泥浆状态，此时流动性强、粘附力大、剪切强度低，易在现有水稻种植机械平板式触土部件作用下漫溢壅阻，对种植装备性能充分发挥造成极大困扰，提高水稻种植机械在此水田土壤环境下的整体工作性能是当前“水田土壤—地面机器系统”研究的重要主题。基于已有水田耕整、播栽技术研究基础，申请者拟以船式水稻直播机为对象，采用田间试验、室内土槽试验、理论分析、虚拟仿真和有限元分析的方法对其船底板、播种滑板等平板式触土部件与扰动水田土壤间挤压、剪切、粘附、沉陷等表面接触及土壤流动规律开展研究，以期阐释触土部件表面特征参数、结构形状及运动参数与扰动水田土壤间的“接触—流变—阻力”耦合关联机制，进而获取触土部件在水田土壤中的降粘减阻表面接触形成条件。研究结果可为水田装备设计与田间通过性能优化、水田机械降粘减阻技术研究提供有益指导，具有重要理论意义和实际应用价值。

由于触土部件与扰动水田土壤间挤压、剪切、粘附、沉陷等表面接触及土壤流动规律复杂。这些耦合作用关系多与土壤粒度组成、水分含量、水分分布、粘附特性以及触土部件表面特征、与土壤接触作用过程等因素密切关联，是产生泥浆涌溢、机具沉陷、运移阻力增加、种植机械通过性降低、功耗增加的主要来源。为阐明触土工作部件与扰动饱和水田土壤间“接触—流变—阻力”耦合作用关系，本项目开展了扰动饱和水田土壤特性研究，揭示了含水率、沉淀时间、载荷、加载速率以及接触方式对土壤流动性的影响规律，提出了水田土壤特性测量技术；以船底及播种滑板等平板式触土工作部件为研究对象，搭建了室内土槽和室外田间试验平台，设计了接地比压测试系统，对平板式触土部件在扰动饱和水田土壤中的接地比压分布和变化规律进行了仿真分析、室内土槽和室外田间试验研究。基于非光滑表面减阻理论，设计了具有凸起结构的非光滑表面平板式触土部件，对其与扰动饱和水田土壤间的粘附力及影响规律进行研究，获得扰动饱和水田环境下的最优非光滑表面结构特征参数；在前期研究基础上，设计了仿生型水稻直播机滑板，在不同垂直载荷、不同牵引速度条件下，并对其在水田土壤中的移动阻力和粘附规律开展了田间试验研究，从而获取土壤流动特性、船体重量、重心分布、船底形状、运动速度与船式水稻直播机运动阻力之间的影响规律，进而阐明船式水稻直播机船底、滑板表面特征、结构及运动参数与滑动阻力、动力特性及接地比压分布规律间的内在联系。本项目研究结果可为水田装备设计与田间通过性能优化、水田机械降粘减阻技术研究提供有益指导，具有重要理论意义和显著应用价值。