Analysis And Experimental Research On Vibration Transmissibility Of Spray Boom Of Wide Sprayer

With the development of giant farms in China,wide boom sprayer is extensively used in modern agriculture as an important plant protection machine with high efficiency.The wide-width sprayer improves work efficiency at the same time:due to the flexibility of the boom structure and the cantilever feature,even a small vibration from the body may cause a large shake at the end of boom,affecting the distance between the boom and the crop canopy,resulting in a decrease in spray uniformity;In addition,the change of driving speed and the uneven terrain of the field road will cause the large angle tilt of the boom to slap the crops,and even the danger of the end of the boom touching the ground.These problems will seriously affect the spray uniformity and the life of the boom.It can be seen that it is of great significance to study the vibration characteristics of wide-boom sprayer for the optimal design and vibration reduction of the boom.In this paper,the 3WP-1200 sprayer is taken as the research object,the modal parameters of the spray boom are obtained by the method of combining finite element analysis and test,and the distribution characteristics of the time and frequency domains are obtained by using the test data of working conditions,and then through the transmission Path analysis calculates the contribution of each path to the boom tip vibration.The main research contents of this paper are as follows:（1）Acquisition of boom modal parameters.In order to check whether there is a resonance frequency range between the natural frequency of the boom and the excitation source frequency,a simplified model of the boom is obtained through Solidworks,and ANSYS Workbench is used to generate a finite element model,set parameters materials,apply loads and constraints,The natural frequency,deformation and mode shape of the boom are obtained by solving the spray the Pre-Stress modal module.The restraint test mode was carried out in the original support mode,and the Poly Max algorithm was used to solve the first 16 modal frequencies of the boom.The simulation and test results show that the maximum error of 6%occurs at the eighth-order frequencies,which are 31.512 Hz and 33.669 Hz,respectively,which verifies the reliability of the boom’s finite element modal parameters.（2）Test and analysis of boom vibration characteristics under working conditions.In order to find out the main excitation source that affects the boom vibration and the vibration transfer characteristics between the excitation source and the boom,the vibration transmission process of the boom is analyzed in an excitation-response manner,and the working condition test and the hammering test are carried out respectively.In the working condition test,the three working conditions of idle speed,road excitation and liquid load were tested respectively,and the acceleration signals at low speed（3 km/h）,medium speed（5 km/h）and high speed（7 km/h）were measured respectively;In the hammer excitation test,when the engine is not working,the force hammer is used as the excitation source to collect the acceleration signal of each measuring point on the boom.The main frequency of each measuring point and the distribution characteristics of vibration energy in the time and frequency domain under different working conditions are obtained by using the time and frequency domain analysis of the vibration acceleration response signal of the measuring point.The excitation source and excitation frequency that have a great influence on the vibration response of the boom are obtained,which provides a theoretical basis for the optimization of the boom structure.（3）Boom vibration transfer path analysis.In order to quantitatively estimate the contribution of each path in the vibration transmission path of the sprayer boom to the vibration response of the boom end,the modeling accuracy and usage conditions of three common TPA methods were compared.Since the vibration source could not be disassembled,a transfer path model of the boom vibration system with 9 reference points and 2 target points was finally established based on the OTPA method.In the OTPA test,the corresponding target point responses Y₀ and Y_h were obtained by using the working condition excitation and the hammer excitation as the excitation sources,respectively.For the crosstalk and measurement noise interference between the input measurement channels,singular value decomposition technology and principal component analysis method are used to eliminate the crosstalk and noise interference between the inputs.The results show that the transfer energy is generally higher in the Z direction of the spherical hinge 1,the Y direction of the spherical hinge1 and the Z direction of the spherical hinge 3.At the same frequency,path 4 has the largest contribution to target point 1,followed by path 2 and path 6.