Search

The structural deformation of a bogie frame manufactured using a composite material was monitored in real time using a distributed optical fiber sensor. The bogie frame contained an internally embedded standard single-mode optical fiber. Performance tests were conducted by applying a vertical load to the middle of the side beams on each side of the composite bogie frame. The strain distribution was monitored using an optical fiber sensor. A distributed optical fiber sensor system based on the Brillouin optical correlation domain analysis (BOCDA) technique with a 3 cm spatial resolution was used. The distributed strain measured using the optical fiber correlated well with the finite element (FE) analysis data, confirming that the composite bogie frame was fabricated as designed. For a vertical load of 182 kN, the maximum strain, which occurred in the middle of the side frame, increased by 1.3 times, as compared with a vertical load of 140 kN. The experiment was able to verify the balance and the structural stability of the left- and right-hand-side beams. Furthermore, it could confirm that there was a concentrated load where the side beam and the crossbeam meet, owing to a mismatch during the assembly of the composite bogie frame. [ABSTRACT FROM AUTHOR]

This study demonstrates the monitoring of distributed strain of rail and girder of a railway bridge occurring during train passage over the bridge’s entire section on a real-time basis by applying a developed distributed optical fiber sensor based on Brillouin Optical Correlation Domain Analysis (BOCDA). The distributed optical fiber sensor system and an algorithm to control as well as to analyze Brillouin gain spectrum signals were also developed. A single-mode optical fiber was attached in the longitudinal direction on the rail and the lower flange of the girder to be used as a sensing fiber of the BOCDA system. Changes in the girder’s strain at the center point of the bridge during the passage of a commercial train were measured at 9 Hz, and the accuracy of this measurement was validated by comparing the measured data with the data from strain gauge. In addition, the distributed strain of a girder and the rail with a length of 40.26 m was measured in real time with a spatial resolution of 31.1 cm. Based on the results of the rail’s strain distribution, the study could identify the location where excessive strain occurred due to an influence of unsupported sleepers on girder of the bridge. [ABSTRACT FROM AUTHOR]

Abstract: 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 (ν B ) is measured that linearly depends on the strain applied to the optical fiber. In the test measurement, the longitudinal strain distribution along a 2.8m rail is measured under different loading conditions with a spatial resolution of 3.8cm and an accuracy of ±15με. [Copyright &y& Elsevier]

Abstract: An I type steel girder was assembled with a concrete upper plateand then placed on two roller supports. Four vertical load actuators were laid on the upper plateto add the vertical load. A single mode optical fiberwas attached on the surface of the lower flange of a composite steel girder bridge with a lengthof 39 m. Longitudinal strain distribution of a composite steel girder bridge is monitoreddirectly using optical fibre sensor system based on Brillouin frequency shift dependency of the strain applied on the optical fiber.Brillouin scattering signal is generated through the Brillouin optical correlation domain analysisat a selected location. Strain data wereacquired at 195 points with the interval of 20cm over the full range.From the strain data over the entire length of the composite steel girder bridge, the strain distribution shape was shownwhen the vertical load was added onthe bridge. [Copyright &y& Elsevier]