Abstract
This paper investigates the effect of rail surface flaws on track impact factors for different track and vehicle conditions. For this purpose, a three dimensional vehicle and track as an integrated system modelled. The vehicle, consists car body, bogie frames and wheelsets, is able to model displacements in vertical and lateral directions. Hertz nonlinear springs utilized to connect vehicle to track structure and simulate the interaction between vehicle and track subsystems. Track comprises rail, rail pads, sleepers and ballast materials. For each subsystem, matrices of mass, stiffness and damping were formed and then matrices of total vehicle-track system considering their interaction were solved. Using FRA spectral density functions for rail irregularities, response of track with different qualities to train dynamic forces obtained. Rail random irregularities, rail corrugation and rail joint defects as three common rail defects have been considered in this paper. For each defects the influence of different track and train parameters on impact factor has been studied. The results of study indicate substantial effect of the depth and frequency of the rail flaws on impact factors. This paper has also considered the impact of vehicle speed on dynamic forces and found the critical speed for each case.
Highlights
Rail surface defects damage the wheels and vehicle and cause a considerable increase in dynamics loads and expedite the deterioration rate of railroad track
Impact factor increases from 18% to 62% when vehicle speed increases from 50 to 200 km/hr. the graph demonstrates that the rate of increase in impact factor is a function of train speed and higher speeds result in increasingly more impact factor
This paper investigated the effect of rail surface defects on dynamic loads
Summary
Rail surface defects damage the wheels and vehicle and cause a considerable increase in dynamics loads and expedite the deterioration rate of railroad track. The result of the study showed that introduction of an insulated joint alters the dynamic characteristics of the track This effect and the introduced surface irregularity of the rail cause high contact load a magnitude that increases with increasing train speed. Wu and Thompson [9] theoretically investigated the impact noise generation due to a wheel passing over dipped rail joints They showed that train speed has a great influence on wheel/rail impact force as well as the level of noise. Jin et al [10] modeled a three-dimensional train–track interaction system and studied rail corrugation for different conditions They concluded that the corrugation with high passing frequencies has a great influence on the dynamic performance of the wheelsets and track, but little on the car-body and the bogie frame. It is shown that under the condition of the same speed and the same wavelength, the deeper the corrugation depth from peak to trough is, the greater the influence on the dynamic performance and the rail material wear are
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