Research on the fastener stiffness of heavy haul railway running 40 t axle-load trains

Research purposes: In order to find the reasonable value of fastener stiffness on the heavy haul railway running 40 t axle-load trains, based on the theory of vehicle-track coupling dynamics, the effect of fastener stiffness on the low frequency vibration was studied by using AAR5 track irregularity spectrum as an excitation. A transient three dimensional wheel / rail rolling contact explicit finite element model was developed to analyze the effect of fastener stiffness on the high frequency vibration by taking the short wavelength irregularity excitation such as rail corrugation, welding joint and the wheel abrasion into consideration. Research conclusions: (1) The fastener stiffness on the heavy haul lines mainly depends on the rail's vertical displacement and the sleeper's load-bearing capacity. The lower limit of the fastener stiffness is determined by rail displacement, and the upper limit is determined by sleeper bearing capacity. (2) The effect of fastener stiffness on low frequency response (below 50 Hz) can be ignored. With the increase of fastener stiffness, the maximum wheel-rail contact force induced by the short wavelength irregularities gradually decreases, and the maximum pressure on rail ditch and ballast stress gradually become larger. The decreasing trend of wheel-rail contact force and ballast stress is slowing down and gradually tends to be stable after the fastener stiffness exceeds 200 MN/m. Relative to the wheel-rail contact force and ballast stress, the pressure on rail ditch is more sensitive to the change of fastener stiffness. (3) Taking the wheel-rail force, rail displacement and sleeper bearing capacity as criteria, as far as a heavy haul ballasted track structure which is characterized by 40 t axle-load and 90 km/h speed is concerned, the optimal dynamic fastener stiffness ranges from 200 MN/m to 250 MN/m in case the maximum allowable rail displacement is 3. 30 mm and rail ditch pressure is 150 kN, and the optimal dynamic stiffness ranges from 200 MN/m to 600 MN/m in case the rail ditch pressure is 180 kN. (4) The research results can provide references for design of track structure in heavy haul railway. © 2016, Editorial Department of Journal of Railway Engineering Society. All right reserved.