Development of a differential test device for eddy current rail inspection

Ruch, Marta; CNEA - AAENDE; Argentina

Gutierrez, M.; Facultad Regional Haedo, UTN; Argentina
Fava, J.O.; Comision Nacional de Energia Atomica; Argentina
Di Fiore, T.A.; Facultad Regional Haedo, UTN; Argentina
Ruch, M.C.; Comision Nacional de Energia Atomica; Argentina
Romero, R.; Facultad Regional Haedo, UTN; Argentina
Vorobioff, J.; Comision Nacional de Energia Atomica; Argentina

ID: ECNDT-0045-2018
Download: PDF
Session: Eddy Current-Techniques 1
Room: H2
Date: 2018-06-14
Time: 11:10 - 11:30

The renewal of railway infrastructure currently underway is promoting at a local level an upgrading of the systems for nondestructive rail inspection, be it prompted by requirements of the new rolling material or for the sake of better and safer operating conditions. Conventional ultrasound has been historically the NDT method most widely used for rail inspection. However, this method is not suitable for the detection of surface flaws, such as the contact fatigue flaws on the running surface (head checks); these surface flaws can be detected by eddy currents [1]. Within this framework we are developing a prototype system for the eddy current inspection of railways. The system uses the near-field send-receive technique in order to inspect planar components of ferromagnetic steels. The inspection head consists of three bobbin coils, the sender in the centre, receivers at both sides, connected in differential mode. The displacement of the inspection head is made by an X-Y positioning device.
Different coils were used in the present work; results from the scan of flat samples of carbon steel with calibrated grooves and of actual rail pieces are presented. Bridge output signals were acquired and processed with a lock-in algorithm in order to get relevant information of the inspected grooves. The influence of lift-off on the groove signals was also studied, with an aim at finding some analysis algorithm which would minimize the influence of lift-off in the case of in-service inspection.

[1] “The important role of eddy current testing in railway track maintenance”; A. Dey, H. M. Thomas and R. Pohl; 17th World Conference on Nondestructive Testing, 25-28 October 2008, Shanghai, China.