Technical Reports

Monitoring Longitudinal Rail Stress Using Diffuse Ultrasonic Backscatter

  • 15
  • Sep
  • 2017
AUTHOR: Federal Railroad Administration
SUBJECT: Rail and Infrastructure Integrity
KEYWORDS: stress in rail; ultrasonic transducers; ultrasound scattering; theoretical model of the scattering process; prototype devices for stress estimations in rail; laboratory and field tests
ABSTRACT: In this report, research was conducted at the University of Nebraska-Lincoln pertaining to the use of ultrasound scattering from polycrystalline grains to estimate and monitor stress in rail. The report presents a comprehensive discussion of the theoretical model of the scattering process, including all measurement parameters, such as the properties of the ultrasonic transducers. The results showed that the grain scattering was sensitive to changes in applied mechanical or thermal stresses, and that each transducer configuration had a different sensitivity to the changes in stress, as expected. This grain scattering approach could be used to quantify the microstructure of rail in the field as a function of position. However, experimental variations could not be reduced to the point of stress estimates being made reliably by using the approaches examined here.