Electromagnetic methods in nondestructive testing of materials

Eddy Current Array Inspection of Zlin 142 Fuselage Riveted Joints

Condition assessment and characterization of materials and structures by means of nondestructive testing (NDT) methods is a priority need around the world to meet the challenges associated with the durability, maintenance, rehabilitation, retrofitting, renewal and health monitoring of new and existing infrastructures including historic monuments. Numerous NDT methods that make use of certain components of the electromagnetic and acoustic spectrum are currently in use to this effect with various levels of success and there is an intensive worldwide research effort aimed at improving the existing methods and developing new ones. The knowledge and information compiled in this book captures the current state of the art in NDT methods and their application to civil and other engineering materials and structures. Critical reviews and advanced interdisciplinary discussions by world-renowned researchers point to the capabilities and limitations of the currently used NDT methods and shed light on current and future research directions to overcome the challenges in their development and practical use. In this respect, the contents of this book will equally benefit practicing engineers and researchers who take part in characterization, assessment and health monitoring of materials and structures.

The purpose of research is the development of application software, including VR-technologies, to increase the number of trained specialists in radiation type of nondestructive testing by reducing the per capita load on radiographic laboratories while maintaining the amount of practical training, acquired competencies and formed relevant professional skills.Methods. Prerequisites for virtualization of the process of training specialists in nondestructive testing of structural materials and fabricated products are defined. The main factors of demand for industrial radiography simulator in relation to the practical part of the educational cycle on radiation type of nondestructive testing are considered. As a result of the analysis the most significant aspects of practical training, available for their virtual realization, are singled out. The results of software implementation of mathematical models of physical and physicochemical processes of ionizing radiation, attenuation and absorption of penetrating radiation within the scope of digital twin of radiographic image generation as a result of simulation of the technological process of radiation type of nondestructive testing are presented.Results. Performed practical implementation of didactic materials in the form of hardware and software VR-simulator as part of digital educational environment to solve the problems of training, retraining, preparation for certification of personnel and providing admission of specialists to work on radiation type of nondestructive testing at facilities. Physical and technological aspects are analyzed, modeling, algorithmization and software implementation of VR-simulator are performed. A comprehensive approach to the creation of a learning environment with the use of digital technologies is presented. Considered are the main components, their goals and objectives. The structure of a practical lesson and illustrations of the training process in a virtual environment are given. The results of approbation of training programs with integration of classes in VR-simulator of industrial radiography have shown that the total time of practice of trainees increases by 40-55% with simultaneous reduction of per capita radiographic laboratory load by more than 25%. The main directions of development and scaling of software and hardware solution using VR-technologies are given.Conclusion. The developed and tested hardware-software solution together with the results of scientific research suggests the possibility of application and development directions of the digital educational system with VR-environment. The proposed approach application will allow to reduce environmental and biomedical risks by reducing the requirements to safety of training with the use of software and hardware solution. Automation of testing task generation and knowledge control procedures on the basis of software tools and mathematical models application, including methods of artificial intelligence, will allow to achieve training term reduction and will contribute to further increase in the number of trained specialists in various types and methods of nondestructive testing. With the functional capabilities expansion and evolutionary development of hardware-software solution (industrial radiography simulator) on the basis of unified modular approach, software libraries and hardware-software interfaces, virtual simulator simplifies organization of the process of specialists training and knowledge control. Practical value of the digital virtual environment (VR-environment) development is revealed due to the transfer and scaling of the obtained hardware-software solution to other types and methods of nondestructive testing according to GOST R 56542-2019 " Non-destructive testing. Classification of types and method".

Nondestructive Testing (NDT) methods provide scientists a way to understand the properties of samples without causing them damage. For an electrochemical device, it is crucial to investigate the behavior of it before, during, and after its operation. Therefore, NDT methods are indispensable for studying such devices.Literature highlights the effectiveness of elastic-wave-based testing methods in the evaluation of electrochemical devices. The Acoustic Emission (AE) method was applied to respectively study the behavior of Solid Oxide Fuel Cells (SOFCs) and Ni-MH batteries, while the Ultrasonic Testing (UT) method was applied to study Li-ion batteries. In our previous research, the signals representing cracking and delamination in SOFCs were successfully distinguished by their peak amplitude, wave shape, and AE energy [1]. The same technique was further used for the evaluation of mechanical damages in SOFCs during the operation [2]. In another study, similarly, the pulverization of the Ni-MH battery electrodes was observed by the AE technique, and frequency peak property was included in the discussion to classify the signals [3]. The UT method was employed to study the relationship between the state of charge of Li-ion batteries and the profiles of ultrasonic waves at different frequencies. The evolution of wave velocity, attenuation, and amplitude were discussed [4]. Based on these researches, elastic-wave-based testing methods are adopted by us.In our present study, the multi-frequencies in-situ ultrasonic monitoring technique was employed to analyze the behavior of the commercial Ni-MH batteries during the operation. Continuous ultrasonic waves at three different frequencies were separately sent into the specimens during charge cycles, and their waveforms were recorded and compared. Specific wave patterns were found near the end of the charge and discharge state, especially from the wave profiles at 750 KHz. The result showed that the evolution of waveform is frequency-dependent, which was also suggested in the literature [4]. Potential explanations for these wave patterns were inferred, including phenomena such as crystal structure evolution, internal pressure shift, and reverse of electrodes.Based on this finding, a new ultrasonic testing/monitoring method considering frequency analysis is also designed. In this new method, signals consisting of elastic waves at a wide range of frequencies with equal intensities are designed to be applied to various electrochemical devices. The application of this method will be included, while the frequency-dependent property of the testing of electrochemical devices will be assessed in combination with the present findings in this study.

The purpose of this paper is to present the results of observation of material degradation process in steel samples under combined conditions of static and cyclic dynamic loading, using selected electromagnetic NDT methods. To evaluate damages a Barkhausen noise observation, an AC magnetization, a magnetic flux leakage and eddy current method were used.

Objects of cultural heritage must be treated with extreme care and the inspection should not cause any kind of material degradation. Electromagnetic methods of non-destructive testing (NDT) enables to achieve detailed information on internal structure of conducting and no conducting materials without any unwanted side effects. Two methods of NDT were considered as the most promising tools for such application: a digital radiography and a terahertz imaging. Results of inspection carried out for two objects are presented.

Review of NDT methods in the assessment of concrete and masonry structures

An accurate evaluation of the residual stress of welded electrical steels with magnetic Barkhausen noise

This paper reviews the most common non-destructive testing (NDT) methods of concrete structures as utilized by the structural engineering industry. The fundamentals of NDT methods are explored in regards to their potential, limitations, inspection techniques and interpretations. The factors that influence the success of NDT methods are discussed and ways to mediate their influence are recommended. Reference is made to standard guidelines for the application and interpretation of the discussed NDT methods. NDT of concrete was found to be gaining increasing acceptance as a means of evaluating the strength, uniformity, durability and other properties of existing concrete structures. Perceptions of NDT inadequacy were attributable to lack of understanding construction materials and NDT methods themselves. The intent of this paper is to address these concerns by identifying and describing the most common successful methods of NDT as applied to concrete structures.

Bridge deck condition assessments in Indiana are primarily reliant on visual inspection. The condition of bridge decks, however, is highly dependent on deterioration under the surface, which includes the corrosion of steel reinforcement and concrete delamination. The implementation of reliable nondestructive testing (NDT) methods can provide information about such internal deterioration, but considering the multiple NDT methods currently available, guidance is needed to find the best approach for assessing bridge decks in the state’s bridge inventory. A research program was conducted to examine various NDT methods with the objective of recommending an effective NDT strategy for network-level and project-level bridge inspections in Indiana that will complement information from traditional bridge inspections and provide asset engineers with improved information for long-term programming decisions. For the study, several consultants used various NDT methods to inspect a set of bridge decks that represented a range of desired test variables. Based on the test results, it was determined that aerial infrared thermography (IRT) is a good network-level method that is capable of scanning a large number of bridges and providing an initial assessment of bridge deck conditions. If significant delamination activity is detected, then follow-up network-level scanning limited to the problematic bridge decks should be performed using vehicle-mounted IRT. For project-level scanning of individual bridge decks, impact echo was found to be reliable and repeatable. For bridges with high-traffic volume for which project-level scanning is needed, a pole-mounted IRT system was found to be effective for evaluating the deck condition.

Crack detection in engineering materials has become a prominent research area due to the severe consequences of potential failures in safety-critical systems such as pipelines, railway systems, welded joints, rotating machinery elements, and load-bearing structures. Although significant advancements have been made in nondestructive testing (NDT) methods, there is currently no single method capable of simultaneously meeting the requirements of high detection sensitivity, quantitative crack characterization capability, and applicability under real service conditions. In this study, literature published from 2000 to the present is reviewed using a systematic and method-oriented approach. Unlike conventional reviews, this study classifies existing methods based on the fundamental physical principles underlying the crack detection mechanism rather than the types of sensors used. The investigated approaches are discussed under the categories of Magnetic Flux Leakage (MFL), direct current electromagnetic and motion-induced eddy current techniques, Eddy Current Testing (ECT) and ACFM methods, thermography-assisted electromagnetic approaches, weak magnetic field and Metal Magnetic Memory (MMM) techniques, magneto-optical and visual methods, hybrid EMAT-ultrasonic systems, and optical/data-driven approaches. Each method is comparatively analyzed in terms of material compatibility, sensitivity to crack type, quantitative evaluation capacity, static/dynamic or real field/load/structure applicability, and system complexity. The cross-evaluation demonstrates that high quantitative accuracy, applicability under real field conditions, and low system complexity cannot be simultaneously achieved in most methods. Consequently, crack detection is evolving as a multidisciplinary research area at the intersection of materials science, sensor physics, and data-driven modeling, necessitating the development of holistic and application-specific sensing strategies in the future.

The paper describes an opportunity for improvement of the widely applied Steam Assisted Gravity Drainage (SAGD) process for in-situ production of bitumen from oil sands deposits. The technical concept aims at Electro Magnetic (EM-SAGD) heating methods assisting the process. Preliminary investigations were carried out to confirm the feasibility of various solutions and evaluate aspects of energy efficiency and environmental impact. This solution targets energy efficiency as well as reduced environmental impact. Different electromagnetic methods have been studied. For sites with overburdens of more than 30m, the inductive method has been found to be the most reasonable in terms of technical and economical feasibility. To evaluate the lifetime efficiency, a reservoir simulator has been coupled to a finite element program, in order to implement the effects of alternating current losses. Different standard cases of thick, shallow and thin reservoir conditions have been simulated in an integrated way of investigation to compare standard SAGD and EM-SAGD. The higher effort of additional electrical heating for EM-SAGD can be justified by lower cost of steam, less amount of water usage and treatment but basically by a higher return from increased bitumen production. In most cases, an earlier production start and a higher recovery rate can be obtained. The proposed solution may contribute a significant enhanced oil recovery at specifically less energy consumption, leading to less impact to the environment in terms of green house emissions and water usage.

Nondestructive testing methods for the early detection of creep damage are reported upon. Correlations between structural parameters and received test signals are discussed in detail. Further, the limiting conditions for testing which apply to the transfer of experimental data to components are considered in detail. The nondestructive test methods used are eddy-current methods, ultrasonic testing, and a thermoelectric measuring method.

Harmonic eddy current testing (HECT) is an electromagnetic non-destructive testing method, which can realize non-contact detection of metal pipeline defects. Eddy current will be produced at the metal pipeline affected by harmonic excitation with multiple frequencies. Meanwhile, the eddy current generated would be uneven due to the disturbance of the defects. In order to detect the abnormalities effectively, the relationship model among the diameter of the pipeline the lift-off height of the probe and the angle of excitation coils was established within this paper. The effect of the magnetic field focusing using different excitation coils models were studied by finite element simulation and the optimal structure of the harmonic excitation coils model was finally achieved. The experimental platform was established, and three types of defects were designed on the top and left side of the pipeline, including circular holes, rectangular grooves, and 45-degree rectangular grooves. The harmonic eddy current magnetic field signals were acquired by the 3-axis Tunnel Magneto-Resistance (TMR) sensors array. The frequency bands of interference and original excitation signal were removed by using Multi-Resolution Analysis (MRA), and thus, the useful signal frequency bands were selected for fusion. The fused signals were input into the bistable Stochastic Resonance (SR) system to realize the noise energy transfer, which was analyzed by the fourth-order Runge-Kutta algorithm and the scale transformation, so as to enhance the energy of the signals at the pipeline defects. The results show that the designed harmonic excitation coils model improves the excitation effect of both sides of the pipeline and expands the coverage of the flaw detection of the pipeline. Besides, the signal processing method proposed within this paper can extract the pipeline defects signal effectively and improve the ability of defects identification. The above research can be helpful on the non-contact non-destructive testing of metallic materials.

The use of non‐destructive evaluation (NDE) for defect detection and failure prediction in structures and specimens is widespread in energy industries, aimed at ageing power plants and pipelines, material degradation, fatigue and radiation damage, etc. At present there are no suitable electromagnetic NDE methods for the measurement and characterization of material degradation, in irradiated samples in particular, which is very important and timely for the nuclear power industry in the UK. This paper reports recent developments in the field of electromagnetic (EM) NDE at Newcastle University, including pulsed eddy current (PEC), pulsed magnetic flux leakage (PMFL), magnetic Barkhausen emission (MBE) and magneto‐acoustic emission (MAE). As different EM methods have different strengths, an integrative EM framework is introduced. Case studies through the second round robin tests organized by the Universal Network for Magnetic Non‐Destructive Evaluation (UNMNDE), representing eighteen leading research groups worldwide in the area of electromagnetic NDE, are reported. Twelve samples with different ageing times and rolling reduction ratios were tested using different magnetic methods among the UNMNDE members. Based on the studies, the complementary characteristics of electromagnetic techniques for NDE are discussed.