Health monitoring of rail structures using guided waves and three-dimensional diagnostic imaging

With the rapid development of high-speed railway around the world, more advanced nondestructive evaluation (NDE) and structural health monitoring (SHM) techniques are required to detect structural damage in its forming stage before the damage jeopardizes the safety of the structures. In this aspect, guided-wave-based diagnostic imaging is a recent research focus, aimed at intuitionally showing the healthy status of the structure under inspection. However, the present diagnostic imaging techniques are mostly two-dimensional imaging methods, which fail to inspect complicated solid structures. In this study, a novel three-dimensional diagnostic imaging technique was developed in conjunction with an active sensor network, capable of real-time monitoring complex solid engineering structures. The ToF-based signal features were extracted from captured guided waves signals, and subsequently applied to define field values. The effectiveness of the approach was examined by identifying a crack introduced into a part of the real rail structure using both FE simulation and experiments. Results have revealed that the developed three-dimensional imaging approach is able to quantitatively visualizing structural damage in complicated solid engineering structures.