Railway wheel defect identification

Wheels are critical components of trains, and their conditions should be therefore monitored.Wheel defects change the wheel-rail contact and cause high impact forces thatare damaging for tracks and trains. Wheel defects can also cause unexpected failuresthat reduce the availability and reliability of the railway system. Several monitoring systemshave been developed to detect and identify the wheel defects. Wheel Impact LoadDetector (WILD) is commonly used to estimate the wheel condition by measuring thewheel-rail contact force.WILDs normally measure the contact force by multiple sensors in different locationsto sample fromdifferent portions of the wheel circumference. The variation in the forcesmeasured by the multiple sensors presents the condition of the wheel. Force ratio anddynamic force are two main indicators using for detecting the defective wheels. Forceratio is the division of the peak force by the average force and the dynamic force is thesubtraction of the peak force and the average force. Force ratio and dynamic force areinfluenced by axle load, and train velocity. In addition, these criteria fail to identify thedefect types. Furthermore, these methods are not useful for monitoring the minor defects.