Research Of Ultrasonic Flaw Detection Technique On Rail Tracks Inspection

The integrity of rails is an important guarantee for traffic safety as defects of tracks in service threaten to personal safety directly.Accurate and efficient inspection of rails regularly is a necessary means to eliminate potential accidents. As the detection obtains the characteristics such as high sensitivity, good point, strong penetration, harmless to human body, ultrasonic detection turns into dominating testing technique of rail tracks both at home and abroad.The article expands research on three aspects of the rail ultrasonic inspection techniques,including theory of ultrasonic flaw detection, ultrasonic flaw detection system and laboratory experiments.First,study the critical techniques on the application of ultrasonic detection.Then,design and debug rail digital ultrasonic detection system.Eventually,verify the path of propagation, waveform conversion and transformation of energy in the specimen and tracks through experiments.The designed system is composed of hardware and software element.Hardware system includes transmitting module, receiving module, data acquisition and storage module, alarm module and USB communication module. Software system is consisted of host and slave computer software: Host computer gets connected to slave computer via USB.VB programming interface can implement waveform display and storage of data.Through infinite impulse band-pass or low-pass digital filter, variable data length envelope extraction spectrum analysis, characteristics of reflected wave in time domain and frequency domain can be acquired; The slave computer programmed in VC language can control transmitting frequency, switch receiving mode and adjust gain of voltage by accepting instructions issued by the host computer.Basing on theories and critical application techniques of ultrasonic detection,the vertical linear,blind area of the system are tested using CSK-IA block, homemade block and rail as experimental subjects.At last,take advantage of the designed system to validate several mathematical model of common noise,to locate specific defects and and analyze dynamic waveform of the defects.