玉米根系—土壤团聚体动态剪切失效特性及仿生破茬齿盘

Cutting-off of hard maize-stubble is a bottleneck problem of conservation tillage, which seriously reduces sowing quality. The program will regard maize root-soil as a special type of aggregates. According to physical and mechanical parameters of root-soil aggregates, root-soil aggregates model and contact models between root-soil and cutting-disc will be built using several advanced technologies, including XCT tomography technology, 3D image reconstruction technology and coupling technology of finite element method and discrete element method. After the above models and simulation parameters are modified through field trials of force measurement and high-speed photography，a visible simulation platform of cutting-aggregates process will be established, and then through cutting process simulation on the platform, the program will reveal dynamic failure properties of maize root-soil aggregates under the dynamic cutting of cutting-disc, further explore the best cutting conditions, cutting manner and cutting power. Simultaneously, mole cricket is selected as the bionic prototype, the program will study the influence mechanism of its fore-leg claws’ and pronotum’s macroscopical configuration and microstructure on cutting and anti-resistance, respectively. Based on the above research results, the program will design structural shape and size of teeth-disc，further optimize its structural parameters and working parameters through simulation test and field trials, eventually, reveal its cutting and anti-resistance mechanism. The research achievements will be expected to supply the theory basis for designing excellent cutting disc and no-tillage farming of drag reduction and energy saving, and provide references for designing other soil-engaging components.

难以破碎的玉米根茬影响免耕播种质量，是制约保护性耕作的瓶颈问题。项目拟将玉米根系—土壤作为特殊团聚体，基于根土团聚体物理力学参数，运用XCT层析成像、三维图像重建及有限元与离散元耦合方法，建立根土团聚体模型及其与破茬刀的接触模型，通过牵引阻力测量和高速摄像田间试验修正模型和仿真参数，进而搭建破茬过程的可视化仿真平台，通过破茬仿真揭示实际工况中玉米根系—土壤团聚体在破茬刀作用下的动态剪切失效特性，探究最佳切割条件、切割方式和切割功率。同时，以蝼蛄为仿生原形，研究前足爪趾和前胸背板的宏观构形和微观形貌对切割和脱附减阻的作用机理。基于上述两方面研究成果，设计仿生破茬齿盘的结构形状和尺寸，通过仿真试验和田间试验优化其结构参数和工作参数，最终揭示其切割和减阻机理。项目成果有望为免耕破茬部件设计和免耕减阻节能提供理论依据，也为其他土壤工作部件设计提供参考。

难以破碎的玉米根茬影响免耕播种质量，是制约保护性耕作的瓶颈问题。项目开展了正交异性的玉米根茬和土壤物理力学及二者界面摩擦参数试验研究，构建了玉米根茬的正交异性材料模型，运用CT扫描和根土分割算法实现了玉米根茬原位无损3D建模，基于上述研究基础构建了玉米根系-土壤团聚体模型及其切削模拟仿真平台，搭建了具备土壤围压模拟功能的根系-土壤团聚体剪切试验台，通过模拟仿真和试验揭示了根系-土壤团聚体的剪切失效特性，探究了不同部位的切削力学特性。同时，以蝼蛄为仿生原形，研究了前足爪趾和前胸背板的的切割和脱附减阻作用机理，基于MicroCT实现了微小尺寸仿生原型3D几何模型重构。基于上述两方面研究成果，研制了基于蝼蛄前足爪趾和附爪大趾的高性能切削齿盘，设计了基于蝼蛄前胸背板的脱附减阻仿生表面。项目成果为免耕破茬部件设计和免耕减阻节能提供理论依据，也为其他土壤工作部件设计提供参考。