| Lifting platform is part of the deep structure of the transport Garage, the vibration of lifting platform has a great influence on the security of the entire transport system?noise emissions and the security of vehicle on the platform.It has an important role to study on the dynamic characteristics of the lifting platform truss for the vibration of the whole system, noise control and energy efficiency.In this study we take PSC8CK-4ZT garage as chief source, the modal analysis function of the finite element software ANSYS is combined with the mathematical model,the modal analysis theory and technology are used to analyze the modal of the lifting platform. The improvement measures are put forward to improve the vertical vibration and horizontal vibration of the lifting platform in the course of operation.The specific research contents are as follows:(1)Based on the theory of mechanical vibration,this text introduces the mechanical vibration mode analysis method of single degree and multi degree of freedom system and describes the influence of viscous damping on the vibration of the system, and the relationship between damping ratio, loss factor and vibration energy.(2)Illustrates how to use of the finite element software ANSYS to solve modal of vibration system. Based on the comprehensive analysis and arrangement of the data of the lifting platform, the vibration of thelifting platform of the garage is decomposed into the vibration of the gear rack transmission system and the vibration of the truss structure.(3)For the gear rack drive system, the rack is fixed on the garage wall, so the vibration of gear rack drive system is shown as the vibration of the gear. In order to analyze the dynamic characteristics of the gear under actual conditions, the mode of the gear is solved in ANSYS. First six modes of the gear are extracted, and compared with the natural frequency and gear rotation frequency compared, the lowest order natural frequency of the gear is far greater than the gear rotation frequency, the vibration of the gear rack is not caused by the resonance, but by gear rotation.(4)The hydraulic motor output harmonic excitation force drives gear to rotate in the rack, establishing dynamics model of gear and rack drive system, due to the very small internal damping of the rigid metal structure,the steel structure energy loss factor is 1×10-4, in the case of ignoring damping effect of solution of the vibration function(and does not take into account the gear rack installation error, pitch error) and draw objective function in time domain graph, find the steady-state vibration amplitude is 0.22 mm, and under damping materials, steady state vibration amplitude only 0.06 mm.(5) Take use of the function of ANSYS modal analysis, put constraint on boundary of mode according to the actual working condition, solve the harmonic response of the truss structure due to the unbalance force caused by the rotation of the hydraulic motor. The results show that the total deformation of the horizontal direction is 8.36 mm, and the amplitude of the beam at both ends of the truss is 0.35 mm.(6)Lifting platform of transversal vibration control depends on contact with the racks of rigid coupling mechanism, in order to reduce the vibration amplitude of the lifting platform in the horizontal direction, therigid coupling roller mechanism of materials by steel structure instead of damping alloy, and then using the ANSYS simulation, 8.36 mm total than the original truss horizontal deformation and horizontal truss beam at both ends of the amplitude of 0.35 mm, with the damping elastic back wheel mechanism of truss horizontal deformation 1.76 mm, amplitude of the horizontal truss beam at both ends of 0.22 mm.The test operation proved that putting damping material on gear rack teeth and changing a rigid back wheel mechanism to Elastic back wheel mechanism with a certain damping can effectively reduce the vibration and the vibration noise of the lifting platform. in the running process of the system. |
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