Study of the surface layers of machined porous materials by the eddy current method

The first publications describing the physical principles of the non-destructive remote field eddy current testing method appeared about 30 years ago. This method allows to significantly expand the field of application of eddy current testing. However, due to the lack of a theoretical justification, this method did not get widespread use around the world. Domestic publications in this area are completely absent, and the descriptions given in few foreign publications often contradict each other. There are no results of full-scale simulation using numerical methods in available domestic and foreign sources. The distinctive feature of this method under consideration is the ability of detecting defects on the external (with respect to the eddy current transducer) side of the tested object, which is impossible for the classical eddy current method due to the limited eddy current penetration depth. The basics of the method were considered, the distinctive features were presented, and the advantages and disadvantages of remote field eddy current testing of metals were pointed out. A numerical simulation with the subsequent analysis of the obtained results has been carried out, the transducer design for remote field eddy current testing is given. The influence of various factors on the change in the added voltage of the signal coil of the eddy current transducer in the presence of a defect in the external wall of the tube was considered. Expressions that determine the optimal ratio of the diameters of the transducer and the tested product were obtained. The values of the test parameters and the limiting wall thickness of the tested ferromagnetic product were determined.

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Influence of Geometrical Features of Material Defects on the Identification Level by the Eddy Current Method

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.237.136 ◽

2015 ◽

Vol 237 ◽

pp. 136-141

Author(s):

Wojciech Jóźwik ◽

Tomasz Samborski

Keyword(s):

Eddy Current ◽

Surface Defects ◽

Roller Bearing ◽

Current Method ◽

Eddy Current Method ◽

Cross Sectional ◽

Tapered Roller Bearing ◽

Geometrical Features ◽

Inner Surface ◽

The Face

The article presents the results of the influence of geometrical features of defects in materials on the level of identification by the eddy current method. The study involved the inner ring of the tapered roller bearing. Four test defects, located at a constant distance from the inner surface, and a subsurface marker defect were performed in the treadmill of the tested ring. The test defects had a constant cross-sectional area in a perpendicular direction to the surface of the eddy current head. The geometrical features of each defect were the following: shape, the perimeter of the defect projected onto the surface of the ring, and the width and height of the defect projected on the face of the measuring head. The study involved an inner surface (subsurface defect detection) and external surface (the study of surface defects). It has been shown that the shape of the defect affects the level of detection using the eddy current method.

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On the Question of Inspecting the Plate with a Crack by the Eddy-Current Method

Russian Journal of Nondestructive Testing ◽

10.1134/s1061830918030038 ◽

2018 ◽

Vol 54 (3) ◽

pp. 182-191 ◽

Cited By ~ 3

Author(s):

V. I. Astakhov ◽

E. M. Danilina ◽

Yu. K. Ershov

Keyword(s):

Eddy Current ◽

Current Method ◽

Eddy Current Method

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An Eddy-Current Method of Flaw Detection in Nonmagnetic Metals

Journal of Applied Mechanics ◽

10.1115/1.4009085 ◽

1941 ◽

Vol 8 (1) ◽

pp. A22-A26

Author(s):

Ross Gunn

Keyword(s):

Eddy Current ◽

Eddy Currents ◽

Flaw Detection ◽

Current Method ◽

Test Sample ◽

Current Pattern ◽

Eddy Current Method ◽

Recorded Performance ◽

Alternating Magnetic Fields ◽

Nonmagnetic Metals

Abstract An equipment suitable for the location of surface or submerged flaws in nonmagnetic metals is described. A predetermined pattern of electrical eddy currents is induced in a perfect test sample by alternating magnetic fields. Sensitive pickup coils properly disposed in relation to the eddy currents measure only the departures of the eddy-current pattern from the pattern in the perfect sample. The departures are indicated on a meter or may be recorded. Performance data are given for a universal type of search unit especially adapted for general surveys.

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