High-Speed Phased Array UT for Rail Flaw Characterization

Preventing broken rail derailments, rail service failures, and interruptions to the rail networks are essential to the safety, integrity, and efficient operation of railroads. Rail service failures are prevented through periodic inspection and removal of rail flaws. Conventional ultrasonic rail inspection systems are finding over 90 percent of the critical flaws, but the undetected flaws are not discovered until they cause a rail break. This paper discusses the use of novel high-speed phased array ultrasonic testing (PAUT) non-destructive evaluation (NDE) technology for inspecting the head and web portions of railroad rail at speeds up to 20 mph. The work was performed on the High Tonnage Loop (HTL) at the Facility for Accelerate Service Testing (FAST) at TTC located near Pueblo, CO. Test results have demonstrated accurate imaging of critical rail flaws and detection consistency on facilities at TTC. These flaws include the transverse defect (TD) under shelling, bolt hole crack (BHC), and weld flaws. In addition, this work also presents the novel approach developed to dynamically compensate for profile wear without operator input as opposed to conventional fixed angle probes which must be physically reoriented by the operator to maintain aim as the inspection vehicle traverses worn rail. Finally, preliminary work done on a high-resolution mode is also presented. The high resolution mode replaces manual hand scanning for flaw verification at specific locations. In the high resolution mode, the probes sweep through a continuum of angles and create a very detailed picture of the rail condition at that location.

References

1. AAR Reference for the graph

2. Libman, M., 2012, “Stepping up rail-flaw detection,” Railway Track & Structures Magazine, Available from: http://www.rtands.com/index.php/track-structure/ballast-ties-rail/stepping-up-rail-flaw-detection.html

3. Clark, R, 2004, “Rail flaw detection: Overview and Needs for Future Developments,” NDT&E International, 37: 111–118.

4. Witte, M., and Poudel, A. 2016, “High-Speed Rail Flaw Detection Using Phased Array Ultrasonics,” Technology Digest TD-16-030, Pueblo, CO: AAR/TTCI. 2012, Phased Array Testing – Basic Theory for Industrial Applications, Olympus NDT, 2nd Edition.

5. Witte, M., Poudel, A., and Kalay, S., 2016, “Rail Flaw Characterization Using Phased Array Ultrasound,” Proc. of 25th ASNT Research Symposium, New Orleans, LA.

6. Wigh, J., 2012, “Development of Improved Rail Inspection System,” Proc. of 2012 AREMA Annual Conference & Exposition, Chicago, IL.

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