Author(s)

X. Duan, Z. Yu, L. Zhu, X. Xu

Abstract

Most modern railways use the continuous welded rail (CWR). A major problem is the almost total absence of expansion joints that can create buckling in hot weather and breakage in cold weather due to rail thermal stresses. A guided wave ultrasound system has been developed to detect the thermal stress in the continuous welded rail. The system operates with three transducers, one for excitation and two for reception, to detect thermal stress based on the acoustic-elasticity principle. We can find the time delay of two receiving transducers when the guided waves transmit through the rail. Then we calibrate the system to establish the relationship between time delay and thermal stress. Finally, we can find the thermal stress by calculating the time-delay of the two receiving transducers. A large scale rail testbed has been designed to simulate the thermal stress on the real track. The system is permanently installed, powered by solar panels and uses a WCDMA network to transmit the monitoring data to the remote serve station. The system has already been installed on some high-speed railway lines in China as a field test; the results indicate that the system is stable. More work needs to be done to improve the accuracy of the detection.

Keywords

continuous welded rail, guided wave, thermal stress