Non-destructive Testing of Near-Surface Defect in Railhead

Published: 14 August 2017

The goal is to develop an accurate condition monitoring tools to be decision support for rail track maintenance actions.

Sponsor: Trafikverket/JVTC 

Researchers: Rayendra Anandika (PhD candidate),Jan Lundberg (PL), och Matti Rantatalo

Duration: 2017-2021

Goal: To develop an accurate condition monitoring tools to be a decision support for rail track maintenance actions.

Projects status and results: Phased array ultrasonic testing (PAUT) has been successfully used to detect near-surface crack in railhead. By its inspection results, the cracks can be observed deeply. Crack profiles, crack tip depth and crack length can be estimated with high accuracy, for instance the absolute error measurement of a crack with tip depth of 3.51 mm is 0.8-18%.
The measurement was verified by comparing the PAUT results with crack images gotten from slicing the inspected railhead. Figure 1 and 2 show an example of comparisons. From the figure, crack profile, crack tip depth and crack length can be observed. Due to diffuse scattering, PAUT cannot show an exact value of tip depth. The scattered signals are relatively high so that the crack tip signals are in a range of depth. In this case, the depth range is 3.23-4.14 mm, while the real depth is 3.51
mm. Regarding this intense scattered signals, further post-processing of the signals may decrease the scattering and thus increase the measurement accuracy. This idea will be taken into account for the next step. Besides that, the capability of PAUT to detect vertical cracks will also be investigated.

Rayendra
Figure 1. 3D image reconstruction of a surface crack in a railhead (unit in mm).
Rayendra 2
Figure 2. An example of PAUT on scanning a shallow surface crack in railhead. Red colors represents crack location.