Eddy Current Probe Design Research Articles

Eddy Currents Probe Design for NDT Applications: A Review.

Eddy current testing (ECT) is a crucial non-destructive testing (NDT) technique extensively used across various industries to detect surface and sub-surface defects in conductive materials. This review explores the latest advancements and methodologies in the design of eddy current probes, emphasizing their application in diverse industrial contexts such as aerospace, automotive, energy, and electronics. It explores the fundamental principles of ECT, examining how eddy currents interact with material defects to provide valuable insights into material integrity. The integration of numerical simulations, particularly through the Finite Element Method (FEM), has emerged as a transformative approach, enabling the precise modeling of electromagnetic interactions and optimizing probe configurations. Innovative probe designs, including multiple coil configurations, have significantly enhanced defect detection capabilities. Despite these advancements, challenges remain, particularly in calibration and sensitivity to environmental conditions. This comprehensive overview highlights the evolving landscape of ECT probe design, aiming to provide researchers and practitioners with a detailed understanding of current trends in this dynamic field.

Optimizing Surface Type Eddy Current Probe Design with Dual Induction for Wobble Noise Suppression

Optimizing Surface Type Eddy Current Probe Design with Dual Induction for Wobble Noise Suppression

Optimization of the design of eddy current probe of parametric type to detect surface cracks

The Paton Welding Journal, 2022, №03. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

ОПТИМАЛЬНЕ ПРОЕКТУВАННЯ ВИХРОСТРУМОВИХ ПЕРЕТВОРЮВАЧІВ ТА АНАЛІЗ МЕТОДІВ РОЗВ’ЯЗКУ НЕЛІНІЙНИХ ОБЕРНЕНИХ ЗАДАЧ

Реалізація апріорі заданих характеристик вихрострумових перетворювачів передбачає використання процедур оптимального синтезу їх конструкцій, зокрема, систем збудження на етапі проектування. Розглянуто формулювання задачі оптимального проектування перетворювача із наперед заданою характеристикою чутливості як некоректно поставленої оберненої нелінійної з математичної точки зору задачі. Проведено огляд та відповідний аналіз математичних методів, що використовуються для розв’язку задач такого класу, а саме, введення шуканого розв’язку до множини коректності, регуляризації із використанням функціоналу Тихонова, методи ітеративної регуляризації, що створені на єдиній схемі поточкової апроксимації зворотного оператора, оптимізаційний метод. Окреслені переваги та недоліки цих методів. Розглянуто особливості, які необхідно враховувати при виборі методу оптимізації, такі як, багатоекстремальність задачі; необхідність пошуку глобального екстремуму; складність топології гіперповерхні пошуку; наявність обмежень, введення яких до цільової функції ускладнює топологію поверхні пошуку; суттєву нелінійність та можливу недиференційованість функції цілі; алгоритмічне або складне аналітичне представлення цільової функції. Враховуючи це, обрано оптимізаційний метод розв’язку нелінійної оберненої задачі проектування системи збудження вихрострумового перетворювача з використанням сучасного метаевристичного стохастичного алгоритму пошуку глобального екстремуму. Даний алгоритм заснований на низькорівневій гібридизації методів оптимізації роєм часток та генетичного алгоритму і забезпечує еволюційне формування складу рою. В дослідженнях доведена доцільність застосування сурогатної оптимізації для розв’язку сформульованої задачі з метою зменшення ресурсоємності оптимізаційних алгоритмів при обчисленнях з використанням складних для розрахунків цільових функцій. Вказано ефективні апроксимаційні техніки побудови метамоделей, необхідні для практичної реалізації сурогатної оптимізації.

Challenges in the Automation of Eddy Current Evaluation for Aerospace‐Spacecraft Propellant Tanks

AbstractAn automated system is designed for Eddy current evaluation of spacecraft components with a proven multi‐axis industrial robot interfaced with dynamic electromechanical distance compensation device (EMDC), automated probe exchange, array eddy current probe, precision component fixtures and turntables, eddy current equipments, centralized control system to control robot and eddy current system with seamless handshake capability. Accuracy of the probe guidance system for the entire test period is ensured by the repeatable probe positioning within ±0.05mm by the robot and a minimal lift off error of ± 50μ, achieved by deploying an automated device with a high precision component turntable with positioning accuracy of £0.005°. The component is aligned initially by LASER and fine alignment is established by Infrared based touch‐tool.Automation of eddy current based evaluation technique has made the system state of the art with high probability of defect detection capability at a lesser evaluation time. Also the system has enhanced process confidence level due to the high positional accuracy of the system in comparison with manual methods, with defect detection capabilities up to depth of 0.12mm on a shell of 0.8 mm thickness. The challenges in automation of the system include intricacies due to component's thickness and also due to the complex hemispherical profile of the component. Fixtures were designed to provide enough support for the fragile components with soft pads at the contact area, and alignment of component in turntable to avoid surface run‐out errors, synchronization between turntable and the robot scanning speed, precision maintenance of lift‐off distance between eddy current probe and component surface, array eddy current probe design with multiple elements ensuring defect detection in any orientation are some of the challenges overcome in the automation of eddy current evaluation technique.The challenges in designing an automated eddy current system for evaluation of propellant tanks were systematically overcome with automation to get better defect characterization capability with reduced test time aiding in design optimization of thin walled metallic structures like propellant tanks.

Hybrid GMR/IR probe to reduce the effects of lift-off

Eddy current testing technique is being utilized in engineering, such as in nuclear steam pipe, aircraft and gas/oil pipeline, due to its sensitivity to small cracks and subsurface defects, immediate results, environmental friendliness, and use in examining complex sizes and shapes of substances. However, the lift-off noise due to irregular inspected materials surface, varying coating thicknesses, or movement of transducers extremely limits the implementation of eddy current testing in a non-disastrous testing which impacts the measure of defect depth on the conductive material. In this paper, a study on hybrid giant magneto-resistance/infrared probe is proposed to minimize the influence of lift-off for detecting the depth defect. The giant magneto-resistance reads the magnetic field which reflects any defect inside the pipeline, and infrared sensors read the movement of each giant magneto-resistance inside the pipeline. The error compensation technique depends on Mamdani fuzzy which examines the interaction that exists between the peak value of giant magneto-resistance and the infrared sensor signal. The eddy current testing inspection system includes details of the giant magneto-resistance–eddy current probe design and instrumentation of the error compensation technique. The measurement method is based on alternating current supply with 30 kHz frequency to ensure that the crack signals are clearly displayed. The proposed method is verified experimentally, and the result shows that the impact of lift-off noise is highly reduced in the eddy current testing technique and enhances the sensor accuracy. The depth defect error caused by 1 mm lift-off is reduced to 7.20%.

A new dual driver planar eddy current probe with dynamically controlled induction pattern

A new planar eddy current probe design is presented. This new concept is capable of dynamically modify the induced eddy currents pattern in accordance with the operational non-destructive testing parameters. The probe is composed by two orthogonally positioned driver traces and a set of sensing coils on each quadrant between the traces. Eddy currents result from the magnetic field contribution of the two driver traces and can be modified by changing the relative amplitude and phase of the currents flowing in the driver traces. Finite Element Modeling was used to simulate the eddy currents patterns and to predict the probe response to defects with different orientations. Experimental validation was carried using a prototype of the probe and artificial defects showing very good agreement with the Finite Element Modeling.

An arrayed uniform eddy current probe design for crack monitoring and sizing of surface breaking cracks with the aid of a computational inversion technique

This study demonstrates that eddy current testing can be an effective method for monitoring the growth of surface breaking cracks with the aid of computational inversion techniques. A uniform eddy current probe with 23 arrayed detectors was designed, and pseudo monitoring tests were carried out to measure signals due to six mechanical fatigue cracks introduced into type 316L austenitic stainless steel plates. In the test the position of the probe was fixed to simulate monitoring. The depths of the cracks were evaluated using a computational inversion method developed on the basis of k-nearest neighbor algorithm. The depths of the mechanical fatigue cracks whose actual depths were 1.1, 2.1, 3.1, 5.5, 6.7, and 8.5mm were evaluated to be 0.9, 1.9, 3.8, 4.3, 7.0, and 5.7mm, respectively. Additional simulations were conducted to demonstrate the stability of the method.

Rotating field eddy current (RoFEC)-probe for steam generator inspection

A novel design of eddy current probe based on rotating magnetic fields is presented for the inspection of steam generator tubes in nuclear power plants. A major advantage of the rotating field probe is that it offers the same functiona lity as that of a rotating probe coil without the need for mechanical rotation, which in turn translates into higher operating sp eed. The probe design is also sensitive to cracks of all orientations in the tube wall.

Simulation based on optimisation of pulsed eddy current probe design

There is a need for a pulsed eddy current (PEC) to detect very small defects and deep buried subsurface flaws reliably in metallic structures such as aircraft wings. This paper reports an investigation into the sensitivity for a pancake PEC probe to variations in the material conductivity of specimens. Three experimental coil parameters are modelled: (a) coil inner radius, (b) coil width and (c) coil height. Based on the predicted signals, the sensitivity of the PEC probe as a function of coil parameters has been formulated. Through matrix numerical simulation experiments using orthogonal array, the weighting of each parameter to the sensitivity has been derived. Subsequently, a theoretical model for probe optimisation is established in order to realise the maximum sensitivity, based on which a probe is designed with improved sensitivity.

Enhancement of EMAT and eddy current using a ferrite back-plate

Electromagnetic acoustic transducers (EMATs) often have an electrically conducting surface behind the coil which we refer to as a back-plate, which could be there to act as an electromagnetic screen or could be a permanent magnet which is part of standard EMAT design. Eddy current probes can share many design features with EMATs, and both are designed to generate an eddy current in the electromagnetic skin-depth of a sample. In this paper we present an analytical solution for a quick and accurate calculation of the eddy current generated by a spiral coil and for the case of EMATs we also calculate the resultant Lorentz force which leads to ultrasonic generation. The Lorentz force can arise from an interaction of the eddy current with either a dynamic magnetic field from the coil or with a static magnetic field from a permanent of electromagnet. Theoretical predictions have shown that in the presence of a ferrite back-plate, the eddy current and the Lorentz force are enhanced greatly, and this has been verified experimentally. These developments will lead to improved EMAT and eddy current probe design.

Eddy current probe design for second-layer cracks under installed fasteners : Beissner, R.E.; Burkhardt, GL.; Creek, EA.; Fisher, J.L. Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 19–24 Jul. 1992. Vol. 12A, pp. 1017–1023. Edited by D.O. Thompson and D.E. Chimenti, Plenum Press (1993). ISBN 0-306-44483-6.

Eddy current probe design for second-layer cracks under installed fasteners : Beissner, R.E.; Burkhardt, GL.; Creek, EA.; Fisher, J.L. Review of Progress in Quantitative Nondestructive Evaluation, La Jolla, California (United States), 19–24 Jul. 1992. Vol. 12A, pp. 1017–1023. Edited by D.O. Thompson and D.E. Chimenti, Plenum Press (1993). ISBN 0-306-44483-6.