Ultrasonic Measurement of Longitudinal Stress in Rail Tracks

This thesis details the investigation of the use of a novel stress relation identity, using pairs of guided bulk ultrasonic waves travelling through a highly incompressible isotropic material, to return a non-destructive and calibration-free measurement of Rail Neutral Temperature, an essential measurement in railway safety maintenance. The angled-wedge method is developed alongside a birefringence method, allowing comparison of accuracy and repeatability.
Several iterations of testing platform are undertaken, and testing conducted on dog-bone tensile specimens in the laboratory and on full rail sections on a test bed. Both methods show some improvement during the course of the investigation, but both techniques encounter significant experimental and material dependant errors.
While the birefringence method returns greater accuracy, the constant need for external calibration limits its usefulness in the rail industry.
The angled wedge method shows initial promise, however, the overall sensitivity of the measurement technique results in experimental noise that exceeds the desired measurement range.
Significant further work would be required to bring either technique to a technology readiness level suitable for deployment in the rail maintenance industry.