Dynamic Characteristics Analysis Of Concrete Pump Truck And Improved Design On Boom Structure

When the concrete pump truck is operating,the boom end vibration is large,which seriously affects the operation stability and safety,so it is necessary to study the dynamic characteristics analysis and the structure improved design of the concrete pump truck.Taking a type of concrete pump truck as the research object,the finite element simulation model and the conveying pipe excitation model of the whole vehicle were established,and the natural frequency and vibration mode of the whole vehicle were obtained through modal analysis.The excitation load of the whole vehicle conveying pipe was solved and applied with MATLAB software and Hyper Works software,and modal superposition method was used to simulate the transient dynamic response analysis.The dynamic response process from the initial state to the steady state under the time domain excitation load is simulated when the vehicle system is in the horizontal dangerous condition.The thickness and stiffness of the boom plate were modified on the original model,and the structure improvement scheme of the best vibration reduction effect was finally determined,and the vibration reduction effect of the improved boom was tested through the actual vehicle water pumping test.By comparing the natural frequencies,it can be seen that the average error between the calculated modal frequencies results and the experimental modal frequencies results is less than 5%,which proves that the correlation between them is well.According to the analysis of the modal influencing factors,every natural frequencies of the upper vehicle system are generally larger than that of the whole vehicle system,and the first order natural frequency increases by8.1%,which verifies the coupling relationship between the upper vehicle system and the lower vehicle system.Each natural frequency of full pipe is reduced by more than 10% compared with empty pipe,which verifies the influence of concrete mass on vibration mode,and the influence of low order mode is more prominent.The accuracy of the finite element model established in this paper is verified by real vehicle modal test.According to the dynamic characteristics analysis,it can be seen that the boom vibration is mainly caused by pumping frequency and its low order harmonics,and the pumping frequency which has great influence on vibration is mainly concentrated within 4 Hz,and it is easy to cause resonance phenomenon when the pumping frequency is lower than 0.2 Hz.It can be obtained through the actual vehicle water pumping test that the vibration reduction effect of the improved pump truck structure can reach 15.3%,which is larger than the expected vibration reduction effect obtained by simulation.And the reliability of this technique is verified by experiments,which provides ideas for further vibration reduction research and stability analysis of concrete pump truck.