In collaboration with other research and industrial partners, a prototype system was developed for high-speed non-contact ultrasound based rail inspection, designed to be mounted to any passenger or freight train. If defects in the rails are found, it will save time and money for the train network, and improve safety for all those using it.
The rail network is getting busier, with trains getting heavier and travelling at higher speeds. Defects in rail track caused by stresses imposed, corrosion, etc. are of growing concern, leading to increased demands on inspection. Surface breaking cracks often cause more serious threats when compared to defects contained within the rail. Rayleigh-like ultrasound waves propagate close to the surface, and hence are inherently sensitive only to surface defects.
I-RAIL uses Electro-Magnetic Acoustic Transducers (EMATs) to generate and receive ultrasound in train rails. These do not need to touch the rail to operate, allowing them to be placed far enough away from the surface so that they won't experience a damaging impact with the rail during normal use, even during high speed operation. Defects can be detected by the attenuation of Rayleigh-like waves; they are predominantly affected by the deepest defect in their path, which reduces the chance of nearby but smaller surface cracks masking more distant but larger surface cracks, unlike existing methods.
The final objective is to detect almost all rail surface defects under critical size, and all critical sized surface defects.
This picture depicts the configuration of the EMATs relative to the rail. An emitting EMAT generates a Rayleigh-like ultrasound pulse in the rail, which interacts with the defect, and is subsequently detected at a receiving EMAT. The attenuation of the pulse can be analysed to quantify the defect depth.
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