On-Line High-Speed Rail Defect Detection;Final rept. Aug 03-Aug 04

摘要

This report presents an ultrasonic method for defect detection in rails that substantially differs from conventional ultrasonic rail inspection. The main difference is in the use of ultrasonic guided waves traveling along the rail running direction. These waves have the potential for improved reliability in detecting transverse cracks and for improved inspection speed when compared to conventional rail inspections. Extensive experimental and numerical tests have been conducted to demonstrate the capabilities of guided waves for the detection of both 'small' (less than or equal to 15% H.A.) and 'large' (greater than or equal to 15% H.A.) transverse cracks in the rail head. Advanced signal processing based on wavelet transforms and automatic pattern recognition has been implemented in the testing. Finally, impact hammers, pulsed lasers and air-coupled sensors have been investigated as practical ways to perform the testing in the field.