Abstract

The railroad rail support trains and contributes to their operation. Internal and surface defects occur on the rail due to various combinations of causes including fatigue loading and cyclic tension and compression among others from the deterioration of the rail along with the temperature differences of seasonal changes. Surface defects such as head check, shelling, and squats start out in the rail head and become internal defects due to poor maintenance, ultimately resulting in rail failure. In order to prevent rail failure, it is important that defects are identified through nondestructive evaluation (NDE) in advance and to carry out maintenance techniques including grinding. NDE methods include MFL, EMAT, and ECT, and among these, the ECT method is a representative method with excellent detection sensitivity that nondestructively inspects metal surfaces such as rails and pipes using an electromagnetic field. Also, since the defect signal is obtained as an electrical signal, the depth, length, and width of defects can be assessed using a defect evaluation algorithm. This study investigated the field applicability and future practical use of the 16 channel eddy current testing equipment and defect evaluation algorithm developed in this study. Therefore, the field applicability of the equipment and defect evaluation algorithm was investigated through the detection of artificial defects with varying size and depth. Afterwards, future practical use was evaluated by inspection of areas of rail that are in use and with naturally occurring surface defects and analysis of their size (length, width), depth, and phenomena.

Highlights

  • With rapid advancement in industries related to transportation, the deterioration of existing infrastructure such as railways and roads has been pointed out as a safety issue

  • Journal of Nondestructive Evaluation (2021) 40:83 shelling, and head check occur, and research is actively carried out on the prevention of accidents such as train derailment caused by rail rupture using nondestructive and maintenance methods including grinding and overlay welding [5,6,7] Various nondestructive techniques are studied in order to establish maintenance standards for the early detection of surface defects, and nondestructive methods used on rails in the field include ultrasonic testing (UT) and eddy current testing (ECT)

  • 3.1 Artificial Defect Sizing machined to a uniform depth of 3 mm, an artificial defect was made on the rail that was used, so the lower part of the head wears more than the upper part, and the amplitude is larger at the lower edge part

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Summary

Introduction

With rapid advancement in industries related to transportation, the deterioration of existing infrastructure such as railways and roads has been pointed out as a safety issue. Information on defects such whether defects exist and their sizes and depths can be obtained through the electrical signal variation such as the impedance between the test surface and the coil sensor [13, 14]. A 16 channel eddy current inspection device was developed, which uses 16 sensors to inspect the entirely of the rail head, and user convenience was taken into consideration, providing real-time 2D images during the inspection to determine whether defects are present along with 3D images of the inspection location to obtain accurate information regarding the shapes and sizes of the defects. Practical use of the equipment was shown for three natural defects on rail that is currently in operation

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