宽幅喷杆喷雾机振动传递特性分析与试验OA

During the operation of boom sprayer,boom vibration occurred caused by excitation from the field road and the tractor's own vibration and thus the unexpended phenomenon of boom end touching the ground frequently happened.It has great influence on the uniformity of droplet deposition and the boom life.In order to suppress the influence of boom vibration on spray quality and interpret the dynamic characteristics of boom vibration transfer,the restraint modal informa-tion of the spray boom under fixed support mode through experimental modal analysis based on 24 m wide boom sprayer;At the same time,the operation modal analysis for support frame as one of passive excitation source was carried out ai-ming at obtaining operating frequencies.On this basis,the finite element model(FEM)of the support frame was estab-lished to clarify the influence of different pesticide tank liquid level on the modal parameters of support frame.Finally,the time-domain and frequency-domain signals of the boom vibration under different working conditions are obtained by ex-periments,combined with the results of modal analysis,the effect of the active and passive excitation sources on the vibra-tion transmission characteristics of the boom is analyzed.The results shown that the first 8 order modal frequencies of the boom are all lower than 120 Hz,the bending deformation dominated mode shape and the deformation is mainly distributed in the first section and the end of the boom.The second-order inertial force frequency of the engine is close to the third-order modal frequency(43.562 Hz)of the boom,the first 16 order modal frequencies of support frame and the first 8 order modal frequencies of boom were at the same range.Under mechanical excitation,the response in the frequency range of 0-150 Hz included the modal characteristics of the entire boom.Meanwhile,the greater vibration loss was found during this frequency range.For idling conditions,the boom vibration was mainly caused by the second-order inertial force with 40 Hz basic frequency,and effect of support frame on boom vibration was negligible.In bumpy road condi-tions,the boom amplitude ascended with the increase of driving speed and the corresponding vibration basic frequencies were 20 Hz and 120 Hz,indicating that boom vibration was caused by the coupling vibration among the road surface,sup-port frame and engine.For smoothy road conditions,the vibration signal was hardly affected by the driving speed.The vi-bration response of the boom was enhanced by the coupling vibration from excitation sources and liquid sloshing.Simulta-neously,the mass and damp of the support frame varied with the variation of liquid amount.The research results can lay theoretical foundation for optimization design and vibration reduction of boom structure.