Study On Vibration Characteristic For Folding Boom System Of Aerial Work Fire-truck

As a kind of rescue equipment which has common structural design and some key technologies with aerial work vehicle, aerial work fire-truck (AWF) is widely used in many aerial work occasions, such as rescue missions. The operating height of the AWF is continuously raises because of the marketing requirements and the folding boom is widely used in AWFs. However, controlling the vibration of the platform during operation is an important way to improve AWFs'working performance and how to solve the bending vibration equation of the boom system is the foundation of this kind of problem.Based on the vibration mechanics and the dynamic study of flexible two-link manipulator, the vibration behavior of folding boom system of a 111m AWF is studied and it provides theory preparation for vibration control of AWFs. Main finished work and researched contents are as follows:(1) The partial differential equation (PDE) and the ODE boundary conditions of the first and second boom are acquired based on the Hamilton Principle. The inherent frequencies and corresponding vibration modes of each boom of the system are obtained based on the beam bending vibration theory of vibration mechanics. Each orthogonal space is defined based on the orthogonality of first and second boom vibration modes, and the system vibration equations of each boom are obtained in this space. At the same time, the dynamic deflection of each boom's tip is simulated in Simulink with actual parameters of a 111m AWF, according to the luffing angle of the second boom.(2) Considering the telescopic boom structure of the first and second boom, the PDEs and ODE boundary conditions of the first and second Variable Cross-Section boom are acquired and the first three inherent frequencies and corresponding vibration modes of each Variable Cross-Section boom system is obtained by Mathematica. According to the orthogonally relation of each Variable Cross-Section boom, the system vibration equations are obtained.(3) The vibration behaviors of the folding boom system are analyzed. Using the dynamic deflection of first Variable Cross-Section boom's tip and the dynamic deflection, angular displacement, linear speed and linear acceleration of second Variable Cross-Section boom's tip as scalar, the dynamic response influence law of the first and second Variable Cross-Section boom's tip are acquired by changing the first boom's angular position, section area and section inertia moment, the second boom's derricking speed, mass at boom's tip, section area and section inertia moment. In addition, the curve of each boom's tip vibration is achieved under the influence of external load.(4) External load and derricking speed of the second boom are the most important factors who influence the vibration behaviors of the second boom, characteristics of the boom system mainly affect the vibration period and the balance position of the boom system.