Research On Rail Dynamic And Static Strain Monitoring Based On Distributed Optical Fiber Grating Sensor

Rail is the foundation of the railway transport system. A lot of information about health status ofthe railway system can be got through static and dynamic strain distribution. Conventional railmonitoring facilities cannot work well because of external factors, which may reduce the reliability ofthe monitoring system, and have a negative impact to safe operation. The optical fiber Bragg grating(FBG) sensor is small, easy-making, anti-electromagnetic interference, high-sensitivity, insulation,etc., which can work well in extreme environments. Thus FBG sensor has broad application prospectsin high-speed rail long distances monitoring, this paper is divided into the following sections:Firstly, the significance of rail important structural health monitoring is elaborated, whichfocuses on the research and application of the current rail structural health monitoring technology andoptical fiber sensing technology.Secondly, according to the FBG sensing properties, combined with material mechanics theory,rail structure mechanics simulation is conducted. Numerical simulation gets a variety of forcecharacteristics under different load conditions, which lay the basis of placing optical fiber sensor. Onthis basis, a distributed fiber Bragg grating sensor network is built, with access to fiber grating centerwavelength trends, so as to realize the static load-bearing structure of the mechanical characteristicsmonitoring.Thirdly, rail structure model is analyzed under dynamic loading conditions by ANSYS finiteelement software, characteristic of the mechanical response and the natural frequencies and dynamicstrain characteristic curve are got through it. On this basis, distributed FBG strain monitoring systemis built, the dynamic response characteristics of each key area is analyzed under shock loading andcyclic loading. Experimental results and numerical simulation have similar trend.Finally, distributed optical fiber rail static and dynamic strain monitoring system applicationsoftware is designed. Based on virtual instrument, combined with LabVIEW graphical programminglanguage, data transfer function is achieved between FBG demodulator and PC and related interactiveinterface modules are developed.