Measurement of wheel load for train during operation using optical fiber sensor

초록

Railway wheel has a complex shape different with the car. It has a small contact area on the rail because of the thread with a fixed slope. Also, the contact point of the wheel varies all the time according to the linearity of the rail. Flange of the wheel acts a role to prevent the derailment of the train. When the train enters the curved region, wheel on the rail moves to the centrifugal force direction under the influence of the centrifugal force to the train. Wheel inside the curve has small diameter compared with the outer wheel. Thus, the axle of the bogie moves along the curve direction of the rail owing to the difference of a rotation radius. Because the wheel does not contact with the rail perpendicularly, the special system is needed to measure the wheel load. When the train does not operate on the rail, a system with a hydraulic pump and wheel lifting components can be used. In this research, we invented a new method to measure the wheel load of the train during operation using optical fiber sensors attached on the 50 kgN rail. Train weight was about 20 ton. It operated 4 times repeatedly with the train speed from 5 km to 20 km. Wavelength change of the optical fiber sensor was acquired with a 1 pm resolution not affected by the environmental electromagnetic noise. Optical fiber sensor data were compared with ESG (Electric Strain Gauge) data. It was well matched. From the analysis of the experimental data, we specified the velocity effect to measure the wheel load. This result can be used in the field test.