Quantitative evaluation of the rotational stiffness of rail cracks based on the reflection of guided waves

This paper proposes an approach to identify the equivalent rotational stiffness of rail cracks based on the reflection of guided waves. The identified rotational stiffness can be adopted to detect the crack and evaluate the safety of the rail. The quasi-bending guided waves propagating in the rail head and web are found and chosen as the detecting guided waves. Considering these guided waves, the relationship between the dynamic parameters of cracks and the power reflection coefficients are deduced theoretically. Cracks are modelled and their rotational stiffness concerning geometric parameters is evaluated. Simulation results indicate that the depth and width of cracks result in the decrease of the rotational stiffness significantly. Field experiments showed that discontinuities in a long distance can be detected by the selected guided waves in the rail head and web with relative errors less than 1% in 100 meters. And artificial cracks were made to validate the proposed method for the rail crack evaluation.