Study On The Vibration Reduction Of Three Fasteners In Metro

The vibration noise generated in the process of subway is a common problem and the reduction of the vibration noise also is a very important issue to keep the train running normally. The track structure of subway is the initial target of vibration transmission and have a significant impact on the subway. Wherein the fastener system is a key part of the track structure and influence the vibration characteristics of the track. For these reasons, it is necessary to have a further study on the vibration characteristics of different fastener systems, respectively.The paper is organized as follows:(1) Carrying out the research and experiment for a subway line in China,the experiments of hammer tapping and vibration acceleration of track under the condition of driving were respectively carried out on the tracks with the common (traditional) fasteners,the short sleeper with resilient rubber (booted sleeper) and the floating rail fasteners.Based on test results, the reduction vibration characteristics of three kinds of tracks was comparatively analysed.(2) The software of finite element ABAQUS was employed to establish the three-dimensional finite element models, such as the tracks with common (traditional) fasteners, short sleeper with resilient rubber (booted sleeper) and floating rail fasteners, model including the implicit and explicit model. For the floating rail fasteners, to ensure the accuracy of the model,the material constitutive model commonly used of rubber block as the direct support of the rail jaw and rail waist was comparatively analysed.(3) A three-dimensional implicit finite element model was used to study the vertical static stiffness of floating rail fastener and analyze the static stiffness variation of different length and thickness of rubber block and study the modal characteristics of three kinds of tracks White noise excitation response was employed to study the reduction vibration characteristics of three kinds of tracks.(4) Three-dimensional explicit finite element model was used to simulate the fall shaft impact and analyze the reduction vibration characteristics of three kinds of tracks.Results of the above study are as following:(1) The elastic rubber material of the floating rail fastener has better ability to predict by the model of Van der Waals. As the length and thickness of rubber block decrease, stiffness value of fastener also decreases. (2) The results of track test and the white noise excitation both show that the track with floating rail fastener has the best effects of reducing vertical vibration, the track with short sleeper with resilient rubber is the second, and the track with common (traditional) fastener is the worst. (3) The drop hammer response analysis shows that as the fastener stiffness decreases, rail vibration acceleration increases, vertical displacement increases and the reaction force per unit area of bed board decreases. With the force of rail passing to the bed board as the evaluation index, we also find that the track with floating rail fastener have the best effects of reducing vertical vibration, the track with short sleeper with resilient rubber is the second, and the track with common (traditional) fastener is the worst. (4) The rail to bed board attenuation of the tracks with common (traditional) fasteners, short sleeper with resilient rubber (booted sleeper) and floating rail fasteners is 24 dB,34 dB and 45 dB, respectively.