Distributed monitoring of rail lateral buckling under axial loading

Distributed fiber optic sensors (DFOS) were used, for the first time, to monitor lateral buckling of a rail under axial loading with different boundary conditions. In the experiments, two types of DFOS systems were used to collect the distributed strain data, and the performance of the two systems was compared. The distributed strain data were used to develop a fitted strain plane at each cross-section along the rail, and axial strain and bending curvature were derived from the fitted strain plane. A data extrapolation method using the distributed curvature data was developed to evaluate the actual boundary conditions at the ends of the rail since they did not match assumed ideal behaviour. The distributed rail deflection along the length of rail was calculated by integrating distributed curvature data and the results were compared with the deflection measured by linear potentiometers (LPs).