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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:

By accurately measuring the near surface cracks at specified spots it will then be possible to see how much of the cracks have propagated further, with respect to the grinding depth, this will give all data that is necessary in order to develop the optimum grinding policy. The problem is that today there is no railway realistic method that have the capability to measure near surface cracks at well-defined spots. The today used eddy current trains only give an approximate measure regarding both crack depth, amounts and positions. Moreover, the ultra-sonic train cannot detect near surface cracks. Thus, the project has also to develop a new method, capable of deliver accurate measurements of crack length and amount of cracks at much specified spots.

Therefore, the goal of the project is the design of a decision support tool for Trafikverket that is considering relevant crack propagation knowledge, to decide the optimum use of grinding from LCC point of view. So far, several methods have been investigated and tested by this project regarding measurement of the cracks. The most successful method is turned out to be based on Phased Array. This method is now undergoing a verification process by means of chipping up rail into very thin pieces where the real cracks can be compared with the Phased Array results. The main conclusions are:

  • A new method using Phased Array is developed which have good potential to measure the development of cracks in the field test
  • Single probes were not successful in this respect
  • Resistance based methods was not successful in this respect
  • Drawbacks regarding crack measurement capacity and accuracy with the  by TRV current used Eddy Current method is concluded
  • A new method for measuring cracks in the rail, partly covered by other above cracks is developed

For the complete research results se the Doctoral thesis by Rayendra Anandika; Non-destructive measurements of near-surface cracks in railheads with focus on ultrasonic inspections. 

Rayendra 2
Figure 1. 3D crack images of region 1 and 2 (the blue dash lines are the rail surface).