Technical Reports

Ultrasonic Inspection of Railroad Rails by Electromagnetic Acoustic Transducers (EMATs)

  • 01
  • May
  • 1986
AUTHOR: Lloyd J. Graham, Jim F. Martin
SUBJECT: Rail and Infrastructure Integrity
KEYWORDS: Defects, Laboratory Testing, Nondestructive Inspection, Field Testing, Shear-Horizontal Waves, Shear-Radial Waves
ABSTRACT: EMATs offer unique characteristics that appear to be advantageous for inspection of railroad rails. These characteristics include the features that EMATs do not require a liquid couplant or physical contact with the object being tested, they can generate ultrasonic wave modes that cannot be produced by conventional transducers and their ultrasonic beams can be steered electronically. This report describes the principal elements, results and conclusions of a four-year program for the development of EMAT systems for the ultrasonic detection and characterization of potentially hazardous defects in railroad rails. Testing in the laboratory on naturally occurring defect specimens and in the field under actual rail testing conditions has shown that EMATs can be adapted for field testing, can detect all the serious types of defects at the required sensitivity level and may be more sensitive to two types of serious defects, the transverse defects and vertical split head defects, than currently available test methods. A long-term side-by-side comparison with existing methods in a field test environment is still needed to confirm that additional defect detection reliability can be achieved by these attractive new rail inspection tools.
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