Ultrasonic guided waves, with the advantages of long propagation distance and wide detection range, can be used for rapid and long-distance detection of railways. The excitation and propagation of a relatively single guided wave mode is conducive to signal processing and damage identification. In this paper, based on the normal mode expansion method, the excitation method of the single wave mode in the rail was studied. At the same time, the empirical formula of the cross-sectional amplitude factor that can consider the tangential excitation was given to analyze the amplitude factors of different guided wave modes in the rail when excited at different positions. The excitation method, verified by finite element simulation, was used to detect the damage of rail head and rail bottom. The results show that the method, with the excitation of relatively single wave mode, can clearly identify the damage echo signal. The method can be used to develop a single-wave mode excitation strategy suitable for damage identification, showing the potential for non-destructive testing and structural health monitoring applications. © 2023 Science Press. All rights reserved.
