Effect of hard spot on dynamic response of railway sleeper

a vehicle-track coupling dynamics model was established based on Timoshenko beam model, vehicle was modeled as a 35 DOF multi-body system, track was modeled as a 3-layer discrete elastic support model, and the motion properties of vehicle/track coupling system were solved by using new-explicit-integration method.The effect of rail vertical, torsional and lateral motions on wheel/rail rolling contact geometry relationship was taken into account, wheel/rail normal forces were calculated by using Hertzian contact theory, and wheel/rail creep forces in rolling contact were computed by using Shen nonlinear creep theory.The support hard spots of sleepers with non-uniform support heights along track were simulated, and the effect of their number and heights on the model was analyzed by using moving rail-supported model.Numerical simulation result indicates that the number of hard spots greatly affects the dynamic responses of track system rather than vehicle system, especially railway sleeper.As the height is 1.0 mm, the maximum rail/sleeper force and tension are almost 2 and 10 times larger than normal values respectively.However, the dynamic responses of vehicle-track coupling system aren't sensitive to the number of hard spots.