Fiber Bragg Grating Accelerometer and Its Application to Measure Wheel-Rail Excitation

This research aims to develop and validate a fiber Bragg grating (FBG) accelerometer, designed with a bearing and flexure hinge structure, to accurately measure medium- and high-frequency vibrations caused by wheel-rail excitation. The structural parameters of the accelerometer are optimized through theoretical mechanics analysis, and its dynamic characteristics are verified by experimental vibration testing and compared with the finite element simulated results. Key findings reveal that the proposed sensor has a wide operational frequency range of 10–1200 Hz and a high acceleration sensitivity of 3 pm/m·s⁻², in addition to excellent linearity and repeatability. Moreover, the sensor demonstrates immunity to temperature variations, making it suitable for use in fluctuating temperature environments. Laboratory model experiment tests of high-speed train tracks show that the FBG accelerometer effectively identifies medium- to high-frequency vibration signals caused by wheel-rail excitation, corroborated by traditional piezoelectric accelerometers. The results confirm the sensor’s ability to capture vertical axle box vibration acceleration (ABVA) and its potential for assessing axle box structural dynamics in high-speed railway applications.