Abstract
A measuring method of rail axial load based on vibration modes is discussed. In particular, the influence of the thermal dependency of rubber pads on the natural frequency of the pinned-pinned mode is investigated. To this end, in the numerical track model a rotational spring is attached at each rail support. Through numerical experiments, it is found that the thermal dependency of the rotational stiffness dominates the sensitivity of the resonant frequency to the axial load, and its consideration is essential to simulate the dynamic nature of tracks. Furthermore, the identification of the temporal equivalent rotational stiffness reflecting the rail pad and fastener is attempted. Numerical results show that the identification using the ratio of bending moment to rotation angle of rail measured around the rail support has the best performance. In this case, the measurement with error of 0.1% is required to assure the identification accuracy of ±50kN.
