Structural Analysis And Pre-deformation Design Of ARM Boom Of DLK22 Ladder Fire Truck

DLK22 Ladder Fire Truck is a kind of compact high-lift fire truck,It possesses three advantages: light and small appearance,flexible system as well as efficient and rapid operation.A variety of rescue methods and integrated design of the working bucket and waterway make the rescue work much faster,operation more efficient and the security protection is more complete and comprehensive.The boom structure is the most critical force component of the ladder fire truck.and the analysis of its structure is of great significance.This thesis is based on the project—design calculation and pre-deformation design of a ladder bridge,which is cooperated by Yanshan University and a construction Machinery Co,Ltd.First of all,the boom structure of DLK22 ladder truck was taken as the research object,analyzing the load of the boom during the working process,and the analytic model of the hinge structure force,hydraulic cylinder thrust and rope tension of the turntable structure was deduced;Then,with the APDL language of ANSYS software as a research tool,a three-dimensional solid parametric finite element model of the boom was built by using a bottom-up modeling approach.Static analysis was performed on the boom.And the analysis results were in good agreement with the analytical solution.The correctness of the finite element model were verified from the theoretical point of view.Meanwhile,the stress of the jib structure under the condition of the limit load was simulated.The stress test experiment was performed on the jib structure.The stress test result was consistent with the finite element calculation result,the correctness of the finite element results was verified from the experimental point of view.Finally,the full-state analysis of the boom structure was performed by using the developed parametric finite element model.The main aspects were as follows:(1)Static analysis of the boom was carried out to determine its stiffness and strength to meet the design requirements.(2)According to the deformation calculated by the static calculation,a reasonable pre-deformation radius was designed to ensure that the deformation after the arm is loadedwas within the controllable range,so that the arm frame was basically straight after the force was applied,and the stretching process was more smooth.(3)Perform a modal analysis of the boom to obtain its low-order natural frequency and associated mode of vibration and determine that the frequency of its own vibration source and external excitation wss far from the natural frequency,and no resonance will occur in the boom.(4)Transient dynamic analysis of the boom was performed to analyze the impact load generated by the rescued person walking into the working bucket,and determined the rigidity and strength of the boom to meet the design requirements.(5)buckling analysis was performed on the boom,and the critical buckling load obtained was much larger than the actual working load,and it is determined that the boom will not suffer from buckling failure.