Optimal Design And Experiment For Boom Structure Of Self-propelled Sprayer Machine

China is a large agricultural country,the crop farming is also the main support for the country’s economic and social development.Grain is the root of a country,is the people’s livelihood needs,is to maintain national security,to ensure the normal and orderly development of society is an important strategic materials.However,in China,crop production is reduced every year due to pests and diseases,resulting in incalculable economic losses,so plant protection operation is an important part of China’s grain security.The self-propelled sprayer machine is an important ground plant protection operation equipment in China,and the performance of the spray boom as a key operation component of the self-propelled sprayer machine directly affects the plant protection operation effect and further affects the grain yield.Most of the existing spray booms are designed empirically,which have problems such as large vibration amplitude of the spray bar,large weight,and material redundancy.In this paper,the static and modal analysis of the existing experience-designed spray boom was carried out,and the structural optimization design was carried out according to the results of the analysis,and the lightweight design increased its operational stability at the same time.The main findings are as follows.(1)A numerical model of the spray boom was established.The 3D modeling software Solid Works was used to establish the simplified 3D assembly model of the spray boom.The chamfers,bolts and other components that did not affect the analysis was removed.The main body of the spray boom was meshed with shell cells,determine the kinematic relationship between the parts based on the kinematic principle of each part of the self-propelled sprayer machine,add constraints,loads and other boundary conditions,and finally establish the spray bar spraying machine finite element model.(2)Based on the establishment of the finite element model,modal analysis and static analysis of the self-propelled sprayer machine was carried out.Meanwhile,replacement of material from Q235 steel to 6063-T6 aluminum alloy.Modal analysis results showed that the first-order modal vibration of the spray boom model was the horizontal plane first-order bending,its frequency was 4.19 Hz,the second-order modal vibration was the horizontal plane second-order bending,its frequency was8.08 Hz,the excitation of the field road was prone to resonance phenomena,resulting in excessive elastic displacement at the end of the spray boom and thus deteriorated the spraying uniformity,the results of the static analysis of the spray boom showed that the maximum stress part of the spray boom was the connection between the large arm and the small arm,The displacement deformation was located in the part far from the central restraint.The maximum deformation occurred at the end of the sprayer boom on both sides,and the maximum displacement was 4.76 mm.(3)Optimized design of spray boom structure based on the analysis.Based on the modal analysis and static analysis,the Optistruct optimization design module was used twice to optimize the structure and material distribution of the spray boom,and the second-order modal frequency was increased from 8.08 Hz to 16.37 Hz by improving the spray boom structure,and the weight was reduced by about 45 %,and the maximum stress on the spray boom was reduced by about 82 %,and the maximum deformation was reduced by about 35 % reduction.The material of spray boom is improved from steel to 6063-T6 aluminum alloy.The location of the maximum stress was still in the weld joint and the connection of each ministry,and the maximum stress value was 53.69 Mpa,which satisfies the yield strength condition of the material and improved the material utilization.(4)Multi-objective optimization of the optimized spray boom.After topology optimization,except for the first-order non-rigid body inherent frequency was less than 10 Hz,all other inherent frequencies meet the requirements,for which multi-objective optimization was introduced to modify the wall thickness of the pipe and plate without changing the original shape.The first-order non-rigid body inherent frequency and mass were set as the optimization target,multi-objective optimization was carried out,and the first-order inherent frequency was increased to 10.7Hz on the basis of a small reduction of the other five-order non-rigid body inherent frequency,which exceeded the excitation frequency range of the road surface and reduced the resonance.(5)Combined with the optimized spray boom structure,a new spray boom was made and field trials were conducted.The vibration conditions of the spraying machine under different road surface unevenness and different positions of the sprayer booms was analyzed.It can be found that the vibration of the optimized spray bar is lower than that of the original spray boom for different vibration degrees;The vibration amplitudes at both ends of the spray bar decreased by 1.10m/s2,2.53m/s2,and 4.90m/s2,3.40m/s2,respectively,meeting the design requirements.