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

摘要

A remote, non-contact system (1) for detecting a defect in a railroad wheel as the wheel is stationary or moving along a railroad track includes: (a) a pulsed, laser light source (10)for generating an ultrasonic wave in the wheel, the ultrasonic wave having a direct portion and reflected and transmitted portions if the direct portion encounters a defect in the wheel, (b) an optical component (12) in the path of the light from the light source (10) for forming the light into a specified illumination pattern so that the generated ultrasonic wave has a specified wavefront, (c) an air-coupled transducer (14) or a group of transducers for sensing the acoustic signal emanating from the wheel that results from the ultrasonic wave traveling through the wheel, and (d) a signal processor (16), responsive to the sensed acoustic signal, capable of distinguishing whether the sensed signal has a component that indicates the existence of a reflected portion in the ultrasonic wave, wherein the presence of such a component in the acoustic signal indicates the existence of a defect in the railroad wheel.