Longitudinal strain monitoring of rail using a distributed fiber sensor based on Brillouin optical correlation domain analysis

A fiber-optic distributed sensor system is configured to measure the longitudinal strain distribution of a rail in real time. The system is based on the Brillouin correlation domain analysis (BOCDA), in which the variation of local Brillouin frequency (νB) is measured that linearly depends on the strain applied to the optical fiber. In the test measurement, the longitudinal strain distribution along a 2.8 m rail is measured under different loading conditions with a spatial resolution of 3.8 cm and an accuracy of ±15 με.

► A distributed fiber sensor system for the railway rail is proposed.
► The system is based on the Brillouin correlation domain analysis.
► The longitudinal strain distribution of the rail was measured in real time.
► The spatial resolution of the strain measurement was 3.6 cm along the rail.