Dispersion curve calculation for SH0-like guided wave locally propagating at the switch rail foot based on wave finite element method

The switch rail is the most critical facility in the railway system for changing the direction of trains. The rail flaw detection car is difficult to detect the switch rail foot, which poses a hidden danger to the safe operation of the railway system. The SH0-like guided wave mainly with horizontal vibration is less affected by the elastic rail fastenings, which has a great potential for switch rail foot inspection. However, unlike the SH0 guided wave in flat plate, the vibration of the SH0-like guided wave in switch rail foot is more complicated. In this paper, the accurate dispersion curve calculation method for the SH0-like guided wave in the switch rail foot is proposed. Through the time domain simulation, the displacement characteristics of the SH0-like guided wave are analyzed by bending motion theory. By applying displacement constraints and fixed constraints to the local model of the switch rail foot, the accurate dispersion curve of SH0-like guided wave is solved using wave finite element method. The two-dimensional Fourier transform (2DFFT) is used for simulation and experimental verification, and the results of the 2DFFT are consistent with the dispersion curve. Defect localization by using SH0-like guided wave in switch rail foot is studied experimentally. Compared with the defect location using the group velocity of SH0 guided wave, the relative error of defect location using SH0-like guided wave group velocity is reduced by more than 8.1 %.