Defects Detection of Access-Constrained Rail Foots , Contacts and Joints using Thermo-acoustic Sensor Technology


  • ​To develop a robust rail inspection system covering the defects not accessible for the conventional NDT techniques.
  • To develop non-contact sensors for long range inspection with large liftoff distances.
  • To  develop robust and intelligent signal processing software for ease of use in rail condition monitoring. 


A mobile NDT system usually uses ultrasonic wave for rail inspection. The wave is conventionally produced from the rail head and cannot detect defects in the rail foot.

The accessible space is limited by other fixed components on the rail, rendering both sources and sensors to be far from the rail foot. As a result, profound attenuation of ultrasonic signals is inevitable making sensors less sensitive to rail foot defects. New techniques have to be found.

Laser-based thermo-acoustic inspection system

 The common thermo-acoustic effect enables a heated material to produce internal ultrasonic waves by localized thermal expansion.  With this in mind, a powerful laser will be applied in our rail inspection system whose energy can be focused to heat any part of rail surface. In this way, the induced ultrasonic signal can be strong enough for the sensors regardless of attenuation from large lift off distance.

Different non-contact sensors will be designed typical defects in the rail foot. The defect types will be intelligently classified with data analytics.