FGB Monitoring Technology Of Train Unbalanced Load And Wheel Tread Wear

The safety of the train running is the most important task of rail transport. The train overload could wear the train and roadbed, and the partial load would affect the weight distribution of each wheel, it wouldl lead to a train derailment when the reduction rate of wheel load reaches a certain level. The wheel tread wear will make the relative height of the running wheel wheel mass centre and the rail track changes. The change will produce impact to the rail track, and when the train running at high speed, the wheel-rail impact load peak produced by the more serious wheelfalts can sometimes be several hundred kN, which is a great risk of train traffic safety. Therefore, studying the train overload or unbalanced load and wheel tread wear by monitoring the strain and temperature of rail is technically feasible and meaningful.The most significant feature of Fiber Bragg Grating(Fiber Bragg Grating FBG) sensor is long-term stability with no zero drift of the signal sensor. It also has outstanding features as high accuracy, high sensitivity, corrosion resistance and anti-electromagnetic interference, long transmission distance, long-term dynamic online monitoring, etc. Therefore, the fiber Bragg grating sensors have more advantages in monitoring rail strain and temperature.This paper first describes the theoretical basis of the fiber grating sensing technology in the monitoring of train unbalanced load and wheel tread wear, and verifies the fiber Bragg grating sensing properties of axial strain by the experimental results. Then it states the detail design of FBG sensor that monitors the train overload or unbalanced load and wheel tread wear, mainly explain the structure design of the FBG strain and temperature compensated sensor, fabrication, installation and protection measures of sensor. And respective compare tests in the laboratory regarding the sensing difference between bare grating and FBG strain gauge. Finally, it introduces the fiber Bragg grating strain and the site installation and protection of temperature compensated sensor in the the depot track, and describes the results of the Bragg grating sensors’monitoring on rail strain and temperature and analyze the relationship of the test data/strain curve and train overloaded or unbalanced and wheel tread wear.The site monitoring data shows the accuracy and reliability of the technology, ballasted ordinary roadbed conditions, the locomotive dynamic weighing error of about4%, and canidentify the wheel tread damage, which could real-time monitor the train running and positively find the hidden safety problems, which plays a very important role in the safe railway operation.