Nonlinear phenomena of short and long wavelength rail defects on vehicle-track interaction

Every day, over 100 million of train traffics are being operated globally. The first priority in train operation management is ‘safety’. During each operation, the dynamic interactions between vehicle and track usually impose vibrations and acoustic radiations and become a moving source of vibroacoustics along the railway network. Especially when there is imperfection of either wheel or rail, the dynamic amplification of loading conditions and reflected vibration effects on infrastructure and rolling stocks is significantly higher. In practice, imperfection of rail tracks is inevitable and can be classified into short wave length and long wave length defects. The imperfections can statistically induce high-intensity impact loadings up to 25% of annual track loading conditions. The short wavelength defects include high-frequency related rail surface defects such as dipped joint rails, rail squats, rolling contact fatigues (RCFs), rail gabs and crossing noses. The long wavelength defects are those associated with low frequency vibrations such as differential track settlement, mud pumping, bridge ends, stiffness transition zone, etc. Most previous studies into vehicle-track interactions were concerned only to a single one of the defect separately. This study is the world first to evaluate the coupling dynamic vehicle-track interactions over coupled short and long wavelength rail defects. The vehicle model has adopted multi degrees of freedom coupling with a discrete supported track model using Herzian contact theory. This paper highlights the nonlinear dynamic impact load factors experienced by railway track components due to wheel/rail contacts. The insight into the nonlinear phenomena will enable predictive track maintenance and risk-based track inspection planning adaptation to enhance public safety and reduce unplanned maintenance costs.