scholarly journals The Improvement of Flaw Detection by the Configuration of Uniform Eddy Current Probes

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 397 ◽  
Author(s):  
Ageng S. Repelianto ◽  
Naoya Kasai
Keyword(s):  
Eddy Current ◽  
Eddy Currents ◽  
Weld Zone ◽  
Flaw Detection ◽  
Ferromagnetic Materials ◽  
Test Pieces ◽  
Induction Condition ◽  
Lift Off ◽  
Almost All

In this review, the principles to detect flaws with uniform eddy currents were presented based on the shape and orientation of the excitation coils and detection coils of the probe. Techniques are applied to detect flaws like cracks, especially on the weld zone surface, of test pieces of non-magnetic and ferromagnetic materials, and have unique features which are immune to the effects of lift-off. In the technique of interest, almost all the probe models developed are the type with tangential rectangular excitation coils. The induction condition and the flaw signal for each probe were discussed based on the shape and orientation of the excitation coils and detection coils of the probe. Finally, the challenge of increasing sensitivity to detect flaws with a uniform eddy current was also presented.

scholarly journals Flaw Detection in Aluminum Plates Using a Rotating Uniform Eddy Current Probe with Two Pairs of Excitation Coils

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1069 ◽  
Author(s):  
Repelianto ◽  
Kasai ◽  
Sekino ◽  
Matsunaga ◽  
Trung
Keyword(s):  
Finite Element ◽  
Eddy Current ◽  
Eddy Currents ◽  
Flaw Detection ◽  
Industrial Sector ◽  
The Self ◽  
Excitation Current ◽  
Test Pieces ◽  
Aluminum Plates ◽  
Detection Coil

The use of eddy currents for detecting flaws in specimens is of considerable significance in the industrial sector. In this study, a new design of a rotating uniform eddy current (UEC) probe, termed the rotating butterfly probe, is presented. The probe consists of two pairs of excitation coils arranged perpendicular to each other, positioned in two layers, and in a detection coil. The excitation and detection coils were installed the pancake orientation, which provides larger induction and enhances the sensitivity of flaws detection. In addition, to generate a rotating UEC distribution with same amplitude in all directions, the number of turns between first and second layers of the excitation coils and the amplitude of excitation current were arranged. Finite element simulations were conducted to confirm that rotating UEC distribution has the same amplitude in all directions. The experiment with the rotating butterfly probe was then conducted. In the experiment, the measured results with the probe was indicated the self-differential and self-nulling properties. Moreover, the probe was successful in detecting flaws in all directions on an aluminum plate. This attribute can be used for the effective inspection of test pieces.

An Eddy-Current Method of Flaw Detection in Nonmagnetic Metals

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.

scholarly journals Investigation of welds by the method of the magneto-optical eddy current flaw detection

2018 ◽  
Vol 185 ◽  
pp. 02014 ◽  
Author(s):  
Nazar Lugovskoy ◽  
Vladimir Berzhansky ◽  
Dmitry Filippov ◽  
Anatoliy Prokopov ◽  
Alexandr Shuyskyy
Keyword(s):  
Mathematical Modeling ◽  
Magnetic Fields ◽  
Eddy Current ◽  
Eddy Currents ◽  
Flaw Detection ◽  
Current Method ◽  
Epitaxial Films ◽  
Eddy Current Method ◽  
Ferrite Garnet ◽  
Conducting Materials

The paper deals with the magneto-optical eddy current method of flaw detection of conducting materials, in which epitaxial films of ferrite garnet are used as sensors. In particular, the possibilities of visualization of welded seams in magnetic and non-magnetic samples, as well as the defectoscopy of the seams themselves, are considered. The second part of the work is devoted to mathematical modeling of the distribution of the magnetic fields of eddy currents near similar defects.

Hardness assessment of induction hardened layers based on the analysis of eddy current signal

2020 ◽  
Vol 24 (4) ◽  
pp. 3-9
Author(s):  
Dominik Kukla ◽  
Mirosław Wyszkowski
Keyword(s):  
Comparative Analysis ◽  
Cross Sections ◽  
Eddy Current ◽  
Eddy Currents ◽  
Induction Hardening ◽  
Current Method ◽  
Current Signal ◽  
Eddy Current Method ◽  
Lift Off ◽  
Non Destructive

The work concerns the assessment of the possibility of identifying changes in hardness of carburized and induction hardened layers using the eddy current method. The tests were carried out on three sets of samples, made of AMS 6414 steel, with different layer thickness, subjected to induction hardening and tempering in a wide temperature range, to obtain differences in layer hardness for each set. The samples of each set, with the layers with a hardness in the range of 760–920 HV, were subject to testes using eddy currents which consisted in the assessment of phase angle changes obtained as a result of the lift – off effect. Standard hardness measurements on the surfaces of the hardened layers were also carried out, and microhardness profiles were made on the cross-sections of the samples. The results of hardness measurements were subject to comparative analysis with the results of non-destructive tests and on this basis it was possible to identify changes in the hardness of layers, based on the results of non-destructive tests.

scholarly journals Analysis of Lift-Off Effect on Transmitter-Receiver Probe in Eddy Current Testing

2020 ◽  
Author(s):  
Qing Zhang ◽  
Xin Li ◽  
Guiyun Tian
Keyword(s):  
Analytical Model ◽  
Eddy Current ◽  
Signal To Noise Ratio ◽  
Ferromagnetic Materials ◽  
Eddy Current Testing ◽  
Probe Design ◽  
Deep Penetration ◽  
Current Testing ◽  
Straight Line ◽  
Lift Off

The Transmitter-Receiver Probe (TR probe), which has improved signal-to-noise ratio, deep penetration depth, and directional measurement is used in pulsed eddy current testing (PECT). Whereas, the lift-off effect on the TR probe is one of the main obstacles. The purpose of this paper is to analyze the lift-off effects on the TR probe and presents a feature for lift-off estimation. Firstly, an analytical model of a TR probe is given based on previous studies. Secondly, on the basics of the analytical model, the spectrum of the PECT signal is studied, and the lift-off effects on the TR probe are analyzed. Then, the lift-off effects under different coil distances are studied and a D Intersect Point (DIP) is proposed for the lift-off estimation. Results show that the TR probe can be used to reduce the lift-off effect for the non-ferromagnetic materials and the ferromagnetic materials. And both the DIP time and amplitude can be used for lift-off estimation. However, the DIP time is better, as its evolution curve with lift-off is a straight line with the same slope. The study is believed to be helpful for the TR probe design, the lift-off measurement, and the thickness assessment and defect quantification.

Reduced False Calls in Eddy Current Images Using Signal Processing

2021 ◽  
Author(s):  
S. B. Mahalakshmi ◽  
Ganesh Seshadri ◽  
Aparna Sheila-Vadde ◽  
Manoj Kumar KM
Keyword(s):  
Eddy Current ◽  
Flaw Detection ◽  
Non Destructive Testing ◽  
Testing Methods ◽  
Destructive Testing ◽  
Noise Measurements ◽  
Component Manufacturing ◽  
Lift Off ◽  
The Time Domain ◽  
Non Destructive

Abstract Non-destructive testing methods are used largely in component manufacturing industries like Aerospace, Renewables and Power to evaluate the properties of a material or the quality of a component by inspecting for cracks and discontinuities without causing damage to the part. Among the many non-destructive testing methods, Eddy current imaging enables efficient flaw detection for surface and sub-surface cracks. However, in typical eddy current inspection, there can be significant number of false calls arising from variation in lift-off and surface anomalies. Discriminating defect signals from false calls can be very challenging. This paper describes a method to reduce false calls by using a wavelet based denoising algorithm and combining it with statistical-based features extracted inside a sliding window in the time domain to efficiently identify the cracks. The results are verified on specimens with cracks of different sizes that are oriented randomly along with locations available for baseline noise measurements.

scholarly journals A Uniform Eddy Current Probe with a Double-Excitation Coil for Flaw Detection on Aluminium Plates

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1116 ◽  
Author(s):  
Ageng Sadnowo Repelianto ◽  
Naoya Kasai ◽  
Kouichi Sekino ◽  
Masaki Matsunaga
Keyword(s):  
Eddy Current ◽  
Eddy Currents ◽  
Signal To Noise Ratio ◽  
Flaw Detection ◽  
High Signal ◽  
Signal To Noise ◽  
Simulation Experiments ◽  
Double Excitation ◽  
Element Simulation ◽  
Excitation Coil

In this present study, a new uniform eddy current (UEC) probe with a double-excitation coil and pancake orientation is proposed. It is confirmed that the probe generates a strong magnetic field induction that increases the intensity of uniform eddy currents; moreover, it is found to be more efficient in power consumption for excitation using a finite element simulation. Experiments are performed to detect different flaw lengths and depths on an aluminium plate. The flaw signal detected by the probe indicates a high signal-to-noise ratio and increases as a function of flaw depth. The quantitative evaluation of flaws with the proposed UEC probe is achieved based on experimental results.

Pulsed eddy current evolution for flaw detection in ferromagnetic materials

2005 ◽  
Vol 17 (1/2) ◽  
pp. 105-111 ◽  
Author(s):  
M. SHAIRA ◽  
P. GUY ◽  
Y. JAYET ◽  
L. DEVILLE ◽  
J. COURBON ◽  
...  
Keyword(s):  
Eddy Current ◽  
Flaw Detection ◽  
Ferromagnetic Materials ◽  
Pulsed Eddy Current

Application of an Ultra-Compact Eddy-Current Transducer for Investigation of Defects in Welded Joints of High-Strength Steel

2021 ◽  
Vol 1037 ◽  
pp. 400-408
Author(s):  
Vladimir N. Malikov ◽  
Alexey Ishkov ◽  
Leonid Nikonov
Keyword(s):  
Eddy Current ◽  
Welded Joints ◽  
Eddy Currents ◽  
Flaw Detection ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
Ferrite Core ◽  
Current Transducer ◽  
Eddy Current Transducer

This article discusses the results of work on the creation of a flaw detection unit, which is focused on the study of high-strength steels. Welded joints of transformer tanks, which are made of steel grade 08G2B, were selected as the object of research. We chose this grade because of the ultra-low carbon content of this material. This opens up opportunities for the application of eddy current nondestructive testing methods. For practical measurements, a scanning device was designed and optimized. It includes a converter that uses the principles of eddy currents and includes three coils assembled on a ferrite core, grade 80NMZ. The device was tested on samples with model continuity defects (cracks and holes). Also, within the framework of the publication, modeling of corrosion defects in welded joints was carried out.

Determination of eddy current losses and hysteresis losses in magnetic circuits of electrical machines

2020 ◽  
pp. 54-58
Author(s):  
S. M. Plotnikov
Keyword(s):  
Eddy Current ◽  
Magnetization Reversal ◽  
Eddy Currents ◽  
Technical Problem ◽  
Electrical Machines ◽  
Eddy Current Losses ◽  
Hysteresis Losses ◽  
Magnetic Circuits ◽  
Core Losses ◽  
Reversal Frequency

The division of the total core losses in the electrical steel of the magnetic circuit into two components – losses dueto hysteresis and eddy currents – is a serious technical problem, the solution of which will effectively design and construct electrical machines with magnetic circuits having low magnetic losses. In this regard, an important parameter is the exponent α, with which the frequency of magnetization reversal is included in the total losses in steel. Theoretically, this indicator can take values from 1 to 2. Most authors take α equal to 1.3, which corresponds to the special case when the eddy current losses are three times higher than the hysteresis losses. In fact, for modern electrical steels, the opposite is true. To refine the index α, an attempt was made to separate the total core losses on the basis that the hysteresis component is proportional to the first degree of the magnetization reversal frequency, and the eddy current component is proportional to the second degree. In the article, the calculation formulas of these components are obtained, containing the values of the total losses measured in idling experiments at two different frequencies, and the ratio of these frequencies. It is shown that the rational frequency ratio is within 1.2. Presented the graphs and expressions to determine the exponent α depending on the measured no-load losses and the frequency of magnetization reversal.

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