Cylindrical guided wave approach for damage detection in hollow train axles

Guided-waves are among the most commonly used techniques for Structural Health Monitoring. However, due to the high thickness-to-wavelength ratio, ultrasonic waves propagating in thick-walled cylindrical structures, such as train bogie axles, exhibit very complex multimodal behavior, thus creating additional challenges to conventional damage detection approaches. As a continuation of our previous work on the guided wave propagation inside a thick-walled cylinder, a novel inspection method using guided wave phenomenon is proposed in this paper, aiming at applications for high-speed trains. The proposed method is based on the near-field mode enhancement phenomenon, which occurs at axle geometrical transitions. Crack-induced alterations to the near-field wave features are used as an indirect indication of the crack presence within specific section of the axle. The method is presented in combination with a modified pulse-echo approach to facilitate defect localization. In addition, to analyze wave propagation phenomena across the wall thickness and verify the feasibility of the method, an axisymmetric model of a hollow axle was developed within the Local Interaction Simulation Approach framework. A simplified model of a train axle was investigated for different damage scenarios involving various sizes and locations.