Study On The Lightweight Of The Ladder Truck Boom Structure

With the rapid development of urban urbanization,the emergency demand for fire protection in cities has increased dramatically,and ladder fire trucks are becoming particularly important.In this paper,by taking the ladder fire truck as the research object,a lightweight study of the arm frame(the middle boom and upper boom)is carried out under the condition of satisfying working intensity and rigidity.And the main research content of this paper is as follows:(1)The structure of various types of the ladder truck is analyzed in detail,and the structure parameters,working conditions and load conditions of the structure of the boom are also determined.According to the actual working conditions of the ladder truck,the structure of the ladder truck is simplified and the 3-dimensional model of the boom structure is established by Solidwrks software,respectively.On this basis,the finite element analysis model is established.(2)According to the lightweight design requirements of the middle boom and upper boom of the ladder truck,a typical lightweight hexagonal honeycomb sandwich structure is selected to optimize the design of the boom.On the basis of satisfying the structure strength and stiffness of the hexagonal honeycomb sandwich,the optimal design of the honeycomb sandwich is the most lightweight and the equivalent mechanical properties are processed.The equivalent mechanical structure of hexagonal honeycomb sandwich structure is used to replace the steel plate structure of the boom,and the lightweight structure model is established on the basis of the original boom structure.(3)Based on the lightweight of the ladder truck boom structure,the critical state(the most dangerous operation state)of the lightweight boom structure is determined.In this state,through static simulation calculation under the maximum concentrated load,the simulation stress nephogram and the simulation displacement nephogram are obtained.Besides,by comparing with the static analysis results of the original boom structure under the same conditions,the results show that the lightweight boom structure not only meets the requirements of working strength and stiffness,but also has better performance than the original boom structure.(4)Through modal analysis of the lightweight boom structure,the natural frequency and corresponding matrix in the first six order are obtained.It is proved that it can resist the external high power disturbance with low frequency,which can meet the dynamic rigidity requirement in the design of the boom structure.On this basis,the transient dynamic analysis is carried out,and the response relation with external load changes is studied according to the simulation results.Besides,the measures for decreasing the lightweight boom structure vibration are presented via analyzing the influence of external shock loading conditions.