Abstract
In South Africa, one of the main lines situated in its Limpopo Province presents symptoms of excessive vehicle-track vibrations. A modal method is adopted to study the difference in dynamic response of corrugated rails resting on the Hytrel/6385 and High Density Polyethylene (HDPE) rail pads. The results for dynamic response of rails on these two types of rail pads are analysed in form of Frequency Response Functions (FRFs). Two positions are considered in obtaining these point FRFs; those are mid-span and on top of sleeper. Resonance modes of significance are excited in a frequency range of 0 – 500Hz on rails resting on both types of rail pads. In view of the entire vibration response window, the FRFs show a more damped vibration response by rail resting on the HDPE than that resting on the Hytrel/6358 rail pad. A Finite Element (FE) modal analysis method is used to investigate vibration mode shapes and corresponding frequencies of the wheelset used by the locomotive operating in the line. In the high frequency range of 350 – 500Hz, the gear-side wheel of a locomotive wheelset proves to be vibrating more erratically than the non-gear side wheel. Clearly pronounced mode shape excited at a frequency of 350Hz and higher are presented.
Highlights
The results showed reasonable agreement of correlation of the corrugation frequencies, with resonance frequencies of the wheelset on track curves
The current study focuses on a high frequency wheel-rail resonance modes
It focuses mainly on the dynamic differences between the responses of rails resting on two types of rail pads i.e. High Density Polyethylene (HDPE) and Hytrel/6358
Summary
A periodic wavelength average of 80 – 90mm was measured [1]. Together with train speeds, this average wavelength per corrugated track curve was used to calculate the “corrugation frequency” for track curves. The current study focuses on a high frequency wheel-rail resonance modes It focuses mainly on the dynamic differences between the responses of rails resting on two types of rail pads i.e. HDPE and Hytrel/6358. The Hytrel rail pad is used on the PY-type concrete sleepers. Rail pads protect sleepers against impact and wear, ensure resiliency during vibration, ensures a higher creep resistance and provides electrical resistance [15]. In his illustration, Thompson [16] considered the dynamic difference of rail pads with a difference in stiffness. The rail pad stiffness significantly affects rail vibration damping and the amount of coupling between rail sleepers [16]. Shows the damage on rail pads due to excessive vibration and Figure 5b. The clamping force of the fastening system is understood to be adequate when every component is at its right place, once the rail pad breaks or find its way out of the system there is no more sufficient clamping, this causes loosening of the fastening system at its entirety and dislocation of its components. is no more sufficient clamping, this causes loosening of the fastening system at its entirety and dislocation of its components
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