LASER-AIR HYBRID ULTRASONIC TECHNIQUE FOR NON-CONTACT TESTING OF RAILROAD TRACKS

摘要

Formed Laser Sources (FLS) using pulsed laser light for generation of ultrasonic stress waves are combined with air-coupled detection of ultrasound to provide for the hybrid non-contact, dynamic and remote ultrasonic testing of structural materials, especially railroad tracks. Using this hybrid technique, multimode and controlled frequency and wavefront surface acoustic waves, plate waves, guided waves, and bulk waves are generated to propagate on and within the rail tracks. The non-contact, remote nature of this methodology enables highs-peed, full access inspections of rail tracks. The flexibility and remote nature of this methodology makes possible the detection of critical cracks that are not easy, or impossible to detect, with current inspection techniques available to the railroad industry. For purpose of field testing, the equipment of the present invention can be located above the top surface of the rail. Cracks of unfavorable positions and orientations at hard to reach geometrical locations can be detected with this Laser-Air Hybrid Ultrasonic approach. By analog amplification, gating, digital signal capture, signal processing and digital data analysis and processing, such rail testing can be performed totally automated.