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Research of Attenuation Characteristics of Bolt Tightening Torque for Rail Vehicle



Rail transit vehicles mostly rely on welding connection technology. However, bolt connection is still used in the installation of hoisting equipment and detachable parts of vehicle. In this paper, the attenuation mechanism of bolt tightening torque is described, and it is concluded that the attenuation of bolt tightening torque can be represented by the attenuation of pretightening force when the friction coefficient remains constant at first. Then the M16×100 bolt of A2-70 material is taken as the research object. The distribution of the actual initial pretightening force under different tightening torques and the decay curve of the pretightening force under axial alternating load are studied through experiments. Based on the above, through a series of tests, the variation law of the bolt pretightening force attenuation was studied using transverse alternating load under different bolt tightening torque, amplitude and loading frequency. The results show that the greater the initial pretightening force of the bolt, the slower the slowdown of the pretightening force. Under the action of the transverse alternating load, the effect of the vibration amplitude on the pretightening force of the bolt is more significant than the frequency. And the value of the vibration amplitude can affect the final attenuation of the bolt pretightening force. The value of the vibration frequency more influences the initial decay speed of the pretightening force. The research results provide reference for stability requirements of bolt quality and selection design of bolts for rail transit vehicle.


bolt, tightening torque, pretightening force, attenuation characteristics, rail vehicle.Text

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