Study On The Reasonable Stiffness And Mechanical Properties Of The FT-1 Fastening System

With the rapid development of modern tramcar in China, the fastener system is one of the important track components. There currently lacks the corresponding theoretical research about the specified fastener system for tramcar in China.In this thesis, the tramcar vehicle-track coupled dynamic model was established, and the reasonable stiffness of the fastener system for modern tramcar was researched. The finite element model of the set of FT-1 fastener system was established. The influences of whole fastener modeling and single component modeling on fastener mechanics were comparatively researched. Also the influence of the different railpad stiffness on fastener system was research. The experimental analysis on the dynamic characters of the FT-1 fastener system was carried out. The main conclusions are drawn as follows.(1) The reasonable stiffness range of the fastener system of modern tramcar was determined, namely 30 kN/mm-50 kN/mm. At this time, the maximum rail vertical displacement is between 0.76 mm and 0.51 mm.(2) The results from whole fastener modeling are more accurate and reasonable than those from single component modeling. Especially for the contact area between components, whole fastener modeling has more advantages than single component modeling. The location and amplitude of stress are more reliable for whole fastener modeling.Under the action of design load, the different railpad stiffness may affect the force and deformation of fastener components. When the railpad stiffness is between 20 kN/mm and 90 kN/mm, the elastic range and stress of the left elastic strip increase gradually, and their increasing trend is the same. At the same time, the maximum stress of the right elastic strip reaches 1665 MPa, and its elastic range decreases gradually. The change of railpad stiffness has a big effect on the force of nylon baseplate. The larger stiffness of nylon baseplate leads to a smaller stress of the intersection between the nylon baseplate bearing lateral force and the baseplate bearing rail vertical force. Thus the influence of railpad stiffness on nylon baseplate should be paid attention to when designing railpad stiffness. When the railpad stiffness is between 20 kN/mm-90 kN/mm, the change value of track gauge decreases from 6.347 mm to 3.644 mm, and the decreasing range of track gauge becomes smaller and smaller. So from the perspective of keeping track gauge, the larger railpad stiffness is better. It is suggested that the reasonable value of fastener stiffness should not be less than 30 kN/mm.(3) The vibration characteristics of the FT-1 fastener system and the frequency response function of the vertical acceleration for rail head and rail foot were obtained experimentally. With consideration of vibration reduction,590Hz、1380Hz、1690Hz and 2630Hz should be focused on. Through the time-frequency analysis, the crux frequency of vibration is 1690 Hz and 2630 Hz. The corresponding measures to reduce vibration should be adopted to effectively inhibit the vibration of track structure.