| Due to long-term ploughing and rotary tillage in the field,the soil at the bottom of the cultivation area forms a compacted plough pan.The plough pan severely impedes the growth of crop roots,making it difficult to obtain nutrients and water from deep soils,causing a decline in crop yields.In addition,the plough pan hinders water infiltration,which can easily lead to surface runoff and soil erosion during rainfall.Therefore,breaking the plough pan is of great significance to protect the soil,increase crop yield,and realize the national strategy of "storing grain in the land".Deep loosening is an effective method to break the plough pan.However,as the main working component of deep loosening operation,the deep loosening device has high resistance and high energy consumption in the process of breaking the plough pan,which limits the promotion and application of deep loosening operation.At present,researchers mainly achieve resistance reduction and consumption reduction by optimizing the structure of deep loose shovel.However,the vibrating deep loosening device has been neglected for a long time due to the lack of innovative ideas and high-precision parameter optimization experiment methods.Based on the excellent soil excavation function of cave rabbits,a bionic energy storage-profiling deep loosening device is innovatively designed by imitating its fore-upper limb unique structure in this study.And the DEM-MBD coupling simulation and field verification experiments are used to reveal its functional advantage mechanism.The main research contents are as follows:(1)Design of bionic energy storage-profiling deep loosening device imitating the fore-upper limb of cave rabbit.According to the energy storage and profiling function during excavation of the cave rabbit fore-upper limb,a bionic energy storage-profiling deep loosening device is designed,which can simultaneously simulate the movement mode of each structure of the fore-upper limb of cave rabbit and its energy storage and profiling functions when excavating soil,and finally the coupling bionic design is realized.According to the operating characteristics of deep loosening,theoretical mechanics,rigid body dynamics and other methods were used to analyze the bionic energy storage-profiling deep loosening device.The analysis shows that the torsional elasticity coefficient optimization range of torque spring(1)and torque spring(3)is between 110-210 k N·mm/°,and the range of torsional elasticity optimization of torque spring(2)is between 220-420 k N·mm/°,which provides guidance for the optimization simulation experiment of core parameters of the bionic energy storage-profiling deep loosening device.(2)Construction of high-precision simulation operation scenarios of bionic energy storage-profiling deep loosening device.The physical and mechanical properties of soil particles were determined,according to the differences in the physical and mechanical properties of soil in different cultivated layers.Four soil particle models of different sizes were established using a single sphere model and Hertz-Mindlin with JKR contact model,and the optimal contact parameters of soil particles were obtained through Box-Behnken Design experiment.Soil DEM models were constructed based on soil particle models of different sizes and contact parameters.The high accuracy of the soil DEM model is verified by cone penetration resistance experiment and soil direct shear experiment,which provides a virtual scene for the DEM-MBD coupling simulation experiment of bionic energy storage-profiling deep loosening device.(3)Bionic energy storage-profiling deep loose device coupling simulation optimization experiments.According to the DEM soil model and the multi-rigid body dynamics model of the two deep loosening devices,the working process the coupling simulation test was carried out on the working process of the deep loosening device based on the coupling algorithm of DEM and MBD,using the discrete element software EDEM and the multi-rigid body dynamics software Recurdyn.The influence of two different deep loosening devices and their core parameters on the average velocity of soil particles,soil disturbance ratio,average resistance of deep loosening,sum of energy storage and energy consumption of deep loosening was obtained.The torsional elastic coefficient-deep loosening energy consumption regression model of bionic energy storage-profiling deep loosening device and traditional vibrating deep loosening device was analyzed.The analysis shows that the deep loosening energy consumption is the smallest when the torque elastic coefficient is 140 k N·mm/°,and the bionic energy storage-profiling deep loosening device is about 22.6% lower than the predicted value of deep loosening energy consumption of the traditional vibrating deep loosening device.The coupling simulation optimization experiment of bionic energy storage-profiling deep loosening device provides a reference and theoretical basis for field verification experiments.(4)The development of the real-time monitoring system for the tillage depth of the bionic energy storage-profiling deep loosening device.Based on the analysis of the kinematic process and tillage depth of the bionic energy storage-profiling deep loosening device,a deep loosening quality monitoring system is developed in conjunction with Python and Lab VIEW,which can achieve real-time measurement and display of the main indicators of deep loosening operation such as the stability of deep loosening depth,the slippage rate of the device and the passing rate of deep loosening operation.(5)Field experiments of the bionic energy storage-profiling deep loosening device and its functional advantage mechanism.Field validation experiments on the bionic energy storage-profiling deep loosening device and the conventional vibration deep loosening device.Under different operating speeds,compared with the traditional vibration deep loosening device,the oil consumption of the bionic energy storage-profiling deep loosening device was reduced by 26.5% to 29.2%,and the deep loosening resistance was reduced by 19.9% to 27.2%;Also,under the same working conditions,the soil disturbance ratio and the stability of the tillage depth of the bionic energy storage-profiling device were better than those of the conventional vibration deep loosening device.In addition,after the same plots had been deep-loosened by two different deep loosening devices,it was found that the soil moisture content after the operation with the bionic energy storage-profiling deep loosening device was significantly higher in the next year’s spring sowing.According to the coupling simulation experiments and field validation experiments,the advantageous mechanism of the bionic energy storage-profiling deep loosening device was analyzed in terms of flexible profiling,tillage depth control,deep loosening resistance reduction,elastic energy storage and deep loosening consumption reduction. |
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