Structural Optimization And Experimental Research Of Tea Plantation Loosening Device Based On Discrete Element Method

Loosening in tea plantation is one of the important links in the tea planting process.It has always been a difficult problem for mechanizing of tea plantation in mountain,since most of the existing soil loosening devices are only suitable for plain areas rather than mountains and hills.As one of the key components of the ripper,the performance of the rotary tiller directly affects the working state of the whole machine and the growth of crops.In this paper,combined with the soil characteristics of tea plantation in mountainous areas,taking the rotary tiller as the research object,a rotary tiller and soil dynamics model based on the discrete element method was established to study the influence of the structural parameters of the rotary tiller on the loosening performance.In the meantime,this thesis tries to find the optimal structural combination of the rotary tiller based on the soil loosening performance regression equation established,and study the influence of key operating parameters on the performance of the loosening device and the performance of this device before and after optimization by contrastive,analysis through field experiments to verify the accuracy and feasibility of the simulation results.The specific studies are as follows:1.Measure the physical and mechanical parameters required in the establishment of the soil discrete element model and choose the HertzMindlin with Bonding model as the contact model between soil particles.The parameters of the simulation model are calibrated through the soil accumulation angle test to establish a soil discrete element model that is closer to the actual situation.2.Take the tangential bending angle,bending radius and single-blade cutting width of the rotary tiller as the experimental factors to carry out uniform experimental design and the rotary tiller-soil dynamics simulation experiment based on the discrete element method.Take the rotating shaft torque of the rotary tiller and the soil disturbance coefficient as the evaluation indicators to determine the primary and secondary factors affecting the working performance,and comprehensively establish the performance regression equation of the rotary tiller.According to the regression equation of the performance of the rotary tiller,it can be concluded that when the bending angle is 112°,the bending radius is 21 mm,and the single-knife cutting width is 38 mm,the test has a lower shaft torque of the rotating and a smaller soil disturbance coefficient.3.Research and analyze the operating factors that affect the working performance of the loosening device and take the forward speed of the implement and the rotational speed of the rotary tiller as the key operating parameters to carry out a single factor test.Analysis of the test results shows that the forward speed of the implement has a significant effect on the torque of the rotary tiller shaft and soil disturbance,while the rotational speed of the shaft has no significant effect on the soil disturbance.4.Field experiments were conducted to compare and analyze the working performance of the rotary tiller before and after optimization.The test results show that the optimized rotary blade reduces the shaft torque by 8.27-13.12% and the soil disturbance coefficient by 5.72-8.16%,under the same working conditions,which verifies the influence of operating parameters on the loosening device and the accuracy and feasibility of the simulation model.The optimized design of the loosening device for mountain tea plantation promotes the mechanization of tea plantation in Fujian,and also provides a reference for the design of loosening devices in other mountainous and hilly areas.