System for non-contact interrogation of railroad axles using laser-based ultrasonic inspection

• US 20060201253A1
• Filed: 03/13/2006
• Published: 09/14/2006
• Est. Priority Date: 03/14/2005
• Status: Abandoned Application

• Current Assignee: Transportation Technology Center, Inc. (Association of American Railroads)
• Original Assignee: Transportation Technology Center, Inc. (Association of American Railroads)
• Inventors: Morgan, Richard L., Gonzales, Kari L., Kenderian, Shant, Bilodeau, James R.
• Application Number:
  US11/374,344
• Publication Number:
  US 20060201253A1
• Time in Patent Office: Days
• US Class Current: 73/643
• CPC Class Codes: G01N 2291/0423 Surface waves, e.g. Rayleigh waves, Love waves
• CPC Class Codes: G01N 2291/0426 Bulk waves, e.g. quartz crystal microbalance, torsional waves
• CPC Class Codes: G01N 2291/044 Internal reflections (echoes), e.g. on walls or defects
• CPC Class Codes: G01N 2291/2626 Wires, bars, rods
• CPC Class Codes: G01N 29/0618 synchronised with scanning, e.g. in real-time
• CPC Class Codes: G01N 29/07 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/221 Arrangements for directing or focusing the acoustical waves electronic orientation or focusing G01N29/262; sound directing or focusing G10K11/26; mechanical steering of sound transducers or their beams G10K11/35
• CPC Class Codes: G01N 29/2418 using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046
• CPC Class Codes: G01N 29/341 with time characteristics

Abstract

A system for ultrasonic inspection of railroad axles uses a laser to project a series of pulses onto the axle to create an ultrasonic signal propagating along the surface of the axle. An air-coupled detector detects the ultrasonic signal at a position on the axle spaced apart from the laser impact region. The ultrasonic signal can then be analyzed to detect the presence of a reflected wave indicating the presence of a defect in the axle.

Claims

1. A system for ultrasonic inspection of railroad axles comprising:

a laser projecting a series of pulses onto a laser impact region of a railroad axle to create an ultrasonic signal propagating along the surface of the axle;

an air-coupled detector receiving the ultrasonic signal at a position on the axle spaced apart from the laser impact region; and

a processor analyzing the ultrasonic signal detected by the air-coupled detector for the presence of a reflected wave indicating the presence of a defect in the axle.

2. The system of claim 1 wherein the processor detects the presence of a reflected wave at least in part by its higher frequency content.

3. The system of claim 1 wherein the processor calculates the location of the defect as a function of the difference in the time of flight of the reflected wave and the time of flight of a direct wave from the laser impact region.

4. The system of claim 1 wherein the laser source is focused to a line.

5. The system of claim 4 wherein the line is orthogonal to the longitudinal axis of the axle.

6. A method for ultrasonic non-contact inspection of moving railroad axles comprising:

remotely projecting a series of laser pulses from a stationary location onto a laser impact region of a railroad axle to create an ultrasonic signal propagating along the surface of the axle;

remotely receiving, from a stationary location, the ultrasonic signal in an air-coupled manner at a position on the axle spaced apart from the laser impact region; and

analyzing the detected ultrasonic signal for the presence of a reflected wave indicating the presence of a defect in the axle.

7. The method of claim 6 wherein the presence of a reflected wave is detected at least in part by its higher frequency content.

8. The method of claim 6 wherein the laser source is focused to a line.

9. The system of claim 8 wherein the line is orthogonal to the longitudinal axis of the axle.

10. The method of claim 6 further comprising the step of calculating the location of the defect as a function of the difference in the time of flight of the reflected wave and the time of flight of a direct wave from the laser impact region.