Electromagnetic Testing Research Articles

Development of magnetic image super-resolution model for nondestructive testing

Electromagnetic testing (ET) is a method in the nondestructive evaluation (NDE) methodology for detecting and evaluating cracks in engineering structures by measuring the distribution of the electromagnetic field. With the development of advanced deep learning (DL) techniques, DL is getting attention in crack detection problems through the measuring signals of NDE systems. However, obtaining the necessary big data for such experiments is a time-consuming and expensive task. Moreover, the quality of the crack detection results heavily depends on the quality and spatial resolution of the input image data. In this research, we solve the above-mentioned problems by proposing a DL-based method on the magnetic image for both the image super-resolution and image denoise. We first build a magnetic image simulation framework for the ET system, and thus, it is possible to build a large dataset for training the DL model. Second, we build a DL model for enhancing the quality of the magnetic image in both the spatial resolution and the denoise signal. This approach helps to reduce the cost of experiments (i.e. reducing the number of sensors for each experiment), sensor fabrication process, and noise removal of the ET system. We evaluate the proposed approach on several cracks with different sizes and shapes of aluminum specimens. The evaluation metrics, such as the structural similarity index measure (SSIM) and root mean square error show good performance of the proposed approach and compared to traditional methods.

Non-Destructive Techniques for the Condition and Structural Health Monitoring of Wind Turbines: A Literature Review of the Last 20 Years.

A complete surveillance strategy for wind turbines requires both the condition monitoring (CM) of their mechanical components and the structural health monitoring (SHM) of their load-bearing structural elements (foundations, tower, and blades). Therefore, it spans both the civil and mechanical engineering fields. Several traditional and advanced non-destructive techniques (NDTs) have been proposed for both areas of application throughout the last years. These include visual inspection (VI), acoustic emissions (AEs), ultrasonic testing (UT), infrared thermography (IRT), radiographic testing (RT), electromagnetic testing (ET), oil monitoring, and many other methods. These NDTs can be performed by human personnel, robots, or unmanned aerial vehicles (UAVs); they can also be applied both for isolated wind turbines or systematically for whole onshore or offshore wind farms. These non-destructive approaches have been extensively reviewed here; more than 300 scientific articles, technical reports, and other documents are included in this review, encompassing all the main aspects of these survey strategies. Particular attention was dedicated to the latest developments in the last two decades (2000–2021). Highly influential research works, which received major attention from the scientific community, are highlighted and commented upon. Furthermore, for each strategy, a selection of relevant applications is reported by way of example, including newer and less developed strategies as well.

Eddy Current Testing Basics and Innovation

Eddy current testing is considered a theoretically challenging technique. Out of all the different nondestructive testing (NDT) methods, the electromagnetic testing (ET) method (of which eddy current testing is a technique) is probably the most difficult for understanding theory. This is perhaps why the last Materials Evaluation Back to Basics paper on eddy current testing is from 2006, which is a long time ago given the amount of innovation in the technique that has taken place since then (Hansen and Peoples 2006). In this paper we will show what has changed due to recent innovations. We first will present the physics, and then explain how modern equipment assists the user in distinguishing between different physical phenomena. Although this paper is on conventional eddy current testing, we will also mention some other ET techniques along with their advantages and disadvantages.

A Microwave Measuring System for Detecting and Localizing Anomalies in Metallic Pipelines

In this work, an innovative system for structural health monitoring of metallic pipes is presented. The proposed system relies on using the pipeline as a waveguide for the propagation of an electromagnetic (EM) signal; possible anomalies in the pipe provoke the partial reflection of the propagating EM signal. Different from previous works that address similar applications, in this work, the EM test signal is injected in the pipeline/waveguide through a coaxial/waveguide transition that is made on the pipe surface (rather than on a cross section as generally done). In practical applications, this strategy would allow connecting more easily the test equipment to the operating, buried pipes. In addition, because reflections caused by anomalies may be difficult to identify with adequate accuracy, the authors have developed a dedicated processing strategy for the analysis of the reflections caused by anomalies. More specifically, by analyzing the measured reflected signal and correlating it to the ideal reflected signal, it is possible to improve the localization of anomalies along the pipe. The proposed system, along with the processing and operating strategies, was validated through full-wave simulations and experimental tests carried out on a steel pipe in the presence of intentionally provoked anomalies.

Investigation of cotton fabric composites as a natural radar-absorbing material

PurposeThe purpose of this paper is to investigate cotton fabric behavior that is exposed to radar waves between selected operation frequencies as an alternative radar-absorbing material (RAM) response. Cotton fabric biocomposite materials were compared with carbon fabric composite materials, which are good absorbers, in terms of mechanical and electromagnetic (EM) properties for that purpose.Design/methodology/approachThe laminated composite plates were manufactured by using a vacuum infusion process. The EM tests were experimentally performed with a vector network analyzer to measure reflection, transmission and absorption ability of cotton fabric, carbon fabric and cotton–carbon fabric (side by side) composite plates between 3 and 18 GHz. The tensile and low-velocity impact tests were carried out to compare the mechanical properties of cotton fabric and carbon fabric composite plates. A scanning electron microscope was used for viewing the topographical features of fracture surfaces.FindingsThe cotton fabric composite plate exhibits low mechanical values, but it gives higher EM wave absorption values than the carbon fabric composite plate in certain frequency ranges. Comparing the EM absorption properties of the combination of cotton and carbon composites with those of the carbon composite alone, it appears that the cotton–carbon combination can be considered as a better absorber than the carbon composite in a frequency range from 12 to 18 GHz at Ku band.Originality/valueThis paper shows how cotton, which is a natural and easily supplied low-cost raw material, can be evaluated as a RAM.

Electromagnetic Testing of Moisture Separation Reheater Tube based on Multivariate Singular Spectral Analysis

Moisture separator reheater (MSR) tubing systems are an important part of a pressurized-water power plant to increase the efficiency of the heat transfer rate. The MSR tubes are finned tubes which are made of ferritic stainless steel (SS439) with a high strength and corrosion resistance characteristics. However, corrosion can appear along with the fins after a long period of operation of the MSR tubes that requires nondestructive testing (NDT) of the MSR tubes’ periodically. Electromagnetic testing (ET) is an efficient NDT method for the inspection of far-side corrosion in the MSR tubes. However, the ET sensor signal is affected by signal noise from the fins. Material degradation that make it challenging to inspect and evaluate the corrosion. In this study, we proposed three ET methods, including magnetic flux leakage testing, eddy current testing and partial saturation eddy current testing, and incorporated with a multivariate singular spectral analysis (MSSA) filter to improve the detectability of the corrosion in the MSR tubes. The proposed MSSA filter was compared with the multivariate wavelet transform filter and Gabor transform filter, and the results showed more efficient and stable results of the MSSA filter in the extraction of the corrosion signal.

Sub-Audio Magnetics (SAM) – Ground-based and HeliSAM FLEM Trials at the Forrestania EM Test Range

Sub-Audio Magnetics (SAM) is a rapid sampling survey technique capable of simultaneous acquisition of data related to the magnetic and electrical properties of the earth. SAM surveys have historically been used for the acquisition of high resolution magnetometric resistivity (MMR) and total magnetic intensity (TMI) data. Recent developments in SAM receiver instrumentation and signal processing have now made the extraction of electromagnetic (EM) data possible due to the exceptionally high data quality now being achieved. SAM data are acquired from a moving platform which makes the technique amenable to applications ranging from ultra-detailed, man-carried or vehicle-towed ground surveys to helicopter-borne acquisition. This paper describes ground-based and helicopter-borne SAM Fixed Loop EM (FLEM) trials conducted over the Forrestania EM Test Range in Western Australia and compares the results with conventionally-acquired (stationary) SAMSON surveys. The trials have demonstrated that SAM FLEM surveys are able to detect high conductance ore bodies at significant depth from a moving survey platform. In either ground or airborne acquisition mode, the SAM technique is shown to be a significant advance toward reducing the cost of deep exploration for high conductance orebodies.

Advances and Researches on Non Destructive Testing: A Review

This paper provides the recent advances and researches about non-destructive testing (NDT) methods for defect characterization in engineering materials and composites. The paper covers the review on the capabilities of NDT applications such as Visual Testing (VT), Ultrasonic Testing (UT), Thermography, Radiographic Testing (RT), Electromagnetic Testing (ET), Acoustic Emission (AE) and shearography testing with respect to advantages and disadvantages of these methods. Further methods are classified on basis of their intrinsic characteristics and their applications. Mostly, an NDT evaluator uses only one non-destructive test method to perform the evaluation. If the scope of work is straight forward, using a single test method is acceptable. However, there are times when a single test method does not provide enough information about the material integrity and thereby combination of different methods is essential. Non destructive testing is widely applied in power plants, aerospace, nuclear industry, military and defence, storage tank inspection, pipe and tube inspection and composite defects characterization. This paper mainly focuses on the scope of NDT application for composite materials.

A review of non-destructive testing methods of composite materials

A review provided about non-destructive testing (NDT) methods for the evaluation of composites. The review considers the capabilities of most common methods in composite NDT applications such as Visual Testing (VT or VI), Ultrasonic Testing (UT), Thermography, Radiographic Testing (RT), Electromagnetic Testing (ET), Acoustic Emission (AE), and Shearography Testing with respect to advantages and disadvantages of these methods. Then, methods categorized based on their intrinsic characteristics and their applications.

A multiple transmitter and receiver electromagnetic system for improved target detection

We have developed an alternative strategy for the inevitable deeper inductive electromagnetic (EM) exploration, which will be required as shallow deposits are exhausted. Rather than using very large magnetic moment ground loops, measurement stations are repeated using many smaller sized loops with smaller moments. The multiple transmitter data are then weighted and summed into a single high signal-to-noise ratio (S/N) composite transmitter. The composite transmitter can be thought of as a postprocessing method that uses the collected multitransmitter data to construct/simulate a transmitter, which maximizes the coupling to a particular target. The appropriate transmitter weights to use will depend on the target location and geometry, and, as such, different weighting schemes allow for the construction of different composite transmitters, each of which will maximally highlight different targets. We have assumed no prior knowledge of the location and orientation of the exploration targets, and we constructed composite transmitters for each possible location of a discretized subsurface and 324 possible target orientations (dipole embedded within a fully resistive medium). A modified difference of squares and a dipole look-up table was used to assess the fit between each composite transmitter and the suggested target location and orientation. Synthetic studies using conductive plate target(s) embedded within a fully resistive medium found that the target locations and orientations could be accurately determined and that the S/N of the composite transmitter was significantly higher than that of standard fixed-loop ground and airborne surveys. In a ground time-domain EM field test, 23 transmitter positions were used, and a shallow target (conductive dike) could be identified using the developed methodology. The composite transmitter data we produced was considerably easier to interpret and had a larger amplitude than that of any one single transmitter.

ZTEM and VTEM airborne EM and magnetic results over the Lalor copper‐gold volcanogenic massive sulfide deposit region, near Snow Lake, Manitoba

The 14.4-Mt Lalor copper-zinc-gold deposit situated in the Flin Flon Greenstone Belt of north-central Manitoba is large ([Formula: see text]) but deeply buried ([Formula: see text]) and was discovered using deep penetrating ground fixed-loop time-domain electromagnetic (EM). Results from three different airborne EM surveys over a five-year span permit comparisons of the system responses over the Lalor volcanogenic massive sulfide deposit region, assisted using 1D-2D-3D inversions. In late March, 2007, soon after its drilling discovery, Hudson Bay Exploration contracted Geotech to fly helicopter versatile time-domain electromagnetic (VTEM) surveys over the region west of Snow Lake, Manitoba. The deposit was not detected due to its large depth of burial ([Formula: see text]) and the lack of magnetic response. In 2009, Geotech carried out a helicopter z‐axis tipper electromagnetic (ZTEM) passive EM test survey over the Lalor deposit, which was successful and led to a larger survey over the area. In 2012, a second VTEM survey test was flown, using the more deeply penetrating [Formula: see text] system. Although it had sufficient penetration to detect the orebody, on-site mine-site development appeared to overprint the deeper [Formula: see text] deposit response. However, a deep ([Formula: see text]) conductive anomaly from a stringer sulfide occurrence, known as South Bull’s Eye, which lies south of Lalor, was well resolved in the ZTEM and [Formula: see text] surveys.

Cabling Arrangement Influence on Repeatability of Immunity EMC Measurements

The paper deals with the analysis of induced current of differential loops of transmission lines during immunity test against electromagnetic field measurement. The influence of geometrical configuration of cabling arrangement on induced current values is surveyed. The problem is described for the case of a short two-wire line creating differential mode loop. The current induced at both ends of the line is the characteristics observed in the performed studies. The comparison between the results of measurements on real physical line, numerical simulations and analytical solution is presented. OST ELECTRICAL devices are connected to external cabling. This ensures power supply, transmission of analogue and digital signals, etc. The cabling is connected with the surrounding environment including electromagnetic (EM) fields. Then it becomes the element of transfer path between the source of disturbance and an electrical device, which becomes subject to disturbance. Hence the present legislation requires the guarantee of immunity against electromagnetic fields of electrical devices available on the market - they have to be tested for immunity. Reproducibility of the testing plays a very important role. During this high frequency immunity test, the configuration of the test place and the testing procedure are the determining elements for the reproducibility of the measurements. This paper is focused on studying the influence of changes in geometric configuration of cabling upon the repeatability of immunity against EM field tests. It is based upon the analysis of impact of the EM field on short transmission lines. The analysis is carried out by measurements, analytical solution as well as numerical analysis. After understanding the problem by means of simple analytical solutions, we focused mainly on the comparison of the measured and simulated results of currents induced on terminating interfaces of the connection cable models. 2. THEORETICAL ANALYSIS