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Ultrasonic signal acquisition platforms generate considerable amounts of data to be stored and processed, especially when multichannel scanning or beamforming is employed. Reducing the mass storage and allowing high-speed data transmissions necessitate the compression of ultrasonic data into a representation with fewer bits. High compression accuracy is crucial in many applications, such as ultrasonic medical imaging and nondestructive testing (NDT). In this study, we present learning models for massive ultrasonic data compression on the order of megabytes. A common and highly efficient compression method for ultrasonic data is signal decomposition and subband elimination using wavelet packet transformation (WPT). We designed an algorithm for finding the wavelet kernel that provides maximum energy compaction and the optimal subband decomposition tree structure for a given ultrasonic signal. Furthermore, the WPT convolutional autoencoder (WPTCAE) compression algorithm is proposed based on the WPT compression tree structure and the use of machine learning for estimating the optimal kernel. To further improve the compression accuracy, an autoencoder (AE) is incorporated into the WPTCAE model to build a hybrid model. The performance of the WPTCAE compression model is examined and benchmarked against other compression algorithms using ultrasonic radio frequency (RF) datasets acquired in NDT and medical imaging applications. The experimental results clearly show that the WPTCAE compression model provides improved compression ratios while maintaining high signal fidelity. The proposed learning models can achieve a compression accuracy of 98% by using only 6% of the original data.

Fused filament fabrication (FFF) with the use of metal-polymer filaments offers a cost-effective solution in additively manufacturing metal parts. Nevertheless, the quality and dimensional characte...

Modeling the electromagnetic response of carbon nanotube (CNT) reinforced composites is inherently a three dimensional (3D) multi-scale problem that is challenging to solve in real-time for nondestructive evaluation applications. This article presents a fast and accurate full-wave electromagnetic solver based on a multi-layer dyadic Green’s function approach. In this approach, we account for the effects of the dielectric slab, where the CNTs are embedded, without explicitly discretizing its interfaces. Due to their large aspect ratios, the CNTs are modeled as arbitrary thin wires (ATWs), and the method of moment (MoM) formulation with distributed line impedance is used to solve for their coupled currents. The accuracy of the inhouse solver is validated against commercial method of moment (MoM) and finite element method (FEM) solvers over a broad range of frequencies (from 1 GHz to 10 THz) and for a wide range of dielectric slab properties. Examples of 100nm long vertical and horizontal CNTs embedded in a 1 μm thick lossy dielectric substrate are presented. The in-house solver provides more than 50 ✕ speed up while solving the vertical CNT, and more than 570 ✕ speed up while solving the horizontal CNT than a commercial MoM solver over the GHz to THz frequency range.

Insulated aerial bundled cables (ABCs) are preferred over conventional bare conductor cables in electrical distribution system as ABCs are more safe, less prone to electricity pilferage and offers higher reliability. However, the degradation phenomenon of ABCs is sudden as compared to conventional cables especially in coastal areas. Sudden failures of ABCs in coastal areas make the maintenance planning challenging. Hence, accurate reliability estimation is required which can enable timely maintenance planning and in turn reducing the chances of failures. A novel reliability model is reported in this work which is derived from historical failure data of particular type of ABCs coupled with the degradation models. The models are based upon the actual environmental conditions experienced by the cables under study. The actual loading data as well as environmental data of two sites of varying distance from Seashore are used to develop the respective reliability models. The reliability prediction from proposed reliability model is then validated using time to failure computation through comparison of historical infrared thermography based Non-destructive testing (NDT) data, acquired at the sites under study, with reference to NDT measurements acquired from the ruptured/failed cable. The validation indicates the efficacy of the proposed reliability model.

As an increasingly recognized optical interferometric technique for nondestructive testing and evaluation, shearography has attracted extensive interest in various industrial applications. However, it suffers from the ignorance of the whole process of dynamic surface deformation and the difficulty in determining the depth-resolved information of inhomogeneities. In this regard, a novel speckle pattern interferometric modality named photothermal radar shearography is proposed. Unlike the differential mode of conventional shearography, the present work focuses on the dynamic surface displacement field channel technique with more comprehensive understanding of the subsurface structural information. With the utilization of frequency modulated photothermal excitation, the depth-distributed information of subsurface structures and inhomogeneities is encoded into the induced dynamic surface deformation. Using Hilbert transform and least-square method solved by discrete cosine transform, the time-domain interference signal of each pixel from the recorded speckle patterns sequence is demodulated and unwrapped to obtain the transient full-field shearographic phase distribution which indicates the dynamic surface deformation. In the meanwhile, incrementally delayed cross-correlation matched filtering allows for the localization of axial energy distribution to generate depth-selective structural display for tomography. This proposed transient-based interferometric methodology thus enables depth-tomographic profiles and three-dimensional visualization of subsurface anomalies for the first time, which significantly improves the superiority and attractiveness of shearography in providing insight into the status, performance and reliability of industry.

It is challenging to apply deep learning in professional fields that lack big data support, especially in industrial nondestructive testings (NDT). To solve this problem, one feasible solution is to introduce the concept of NDT physics into a deep neural network to compensate for the network's poor predictive abilities when trained on small datasets. Therefore, we propose a physics-informed deep neural network, named GuwNet, using a unidirectional oblique-focusing (UOF) high-frequency, high-order shear horizontal guided wave electromagnetic acoustic transducer (EMAT) to quantify microcrack defects more accurately. We study the quantification principle of microcrack defects suitable for UOF-EMAT, and propose a network using physical knowledge regarding this theory including the network structure and loss functions design. Compared with traditional nonphysics-informed methods, the length, depth, and direction of the quantification errors are reduced to 0.127 mm, 0.279% dt, and 1.843', respectively, and the average quantification error is reduced by more than 80%

This paper introduces the applications of neutron radiography and tomography to improve maintenance and aging management programs in research reactors. Egypt second research reactor (ETRR-2) has an advanced neutron radiography/tomography facility and it is used to shoot and test different objects such as concerning antiquities, industry and applied research in various fields. Neutron radiography/tomography (NR/T) techniques offer ideal opportunities for nondestructive testing (NDT) evaluations. It has been possible to benefit from the applications and use of radiography to help improve maintenance of components and systems as well as aging management programs for the ETRR-2. This work proposes successful applications of NR/T to inspect and test different safety and safety related components such solenoid valves and the shielding tube of the defective fuel instrument to predict both damage and edging of these systems. Also, the NR technique monitored successfully the behavior efficiency of an air filtering unit (AFU) for dust removal from ventilation system in the research reactors. Additionally, we measured the capability of protective maintenance procedures to remove impurities or blockage from a stainless steel filter (SSF) used in water treatment system. NR/T techniques are successfully applied and enhanced both maintenance and ageing management programs of ETRR-2 instrumentation, equipment and systems.

Structural health monitoring is the technique which evaluate and analyze materials in the production and service process. In this paper, the basic principles and characteristics of terahertz, infrared, visible-multispectral and X-ray nondestructive testing technologies with different penetration rates, spectral energy, detection accuracy and system complexity are reviewed. Based on the types and causes of defects in aerospace materials, the corresponding testing techniques and nondestructive testing technology for different defects are also summarized. Finally, the image processing technology of each detection technology is analyzed. In practice, it is usually necessary to select one or more test methods according to the material properties and damage types. The differences in imaging techniques and processing algorithms are the major obstacles to joint multispectral detection. Although there have been preliminary studies on the methods of combining and associating image data under different spectra, further research is needed on how to integrate more spectra for new, more complex applications.

Graphical abstract, Highlights • The mappings between micro cracks and diffraction pattern curves were revealed based on GIXD and MD. • Surface and subsurface defects of CaF2 crystals induced by abrasive machining were evaluated and characterized accurately. • MD simulated results agreed well with the experimental results. • This work provided a novel technology for nondestructive testing of defects of single crystals at nano- and micro- scales., Introduction Surface and subsurface defects were easily induced during abrasive machining process of optical crystals due to their high brittleness. Accurate characterization of these defects is the prerequisite for obtaining optical components with high surface integrity. Objectives This work aims to evaluate subsurface defects of CaF2 single crystals induced by abrasive machining, the mappings between micro cracks and diffraction pattern curves, and the influence of micro cracks on lattice structures. Methods Molecular dynamics simulation, grazing incidence X-ray diffraction experiments and cross-sectional TEM detection were used in this work. Results In grazing incidence X-ray diffraction (GIXD) detection experiments on lapping and polished specimens, shifts phenomenon of the peak position under the non-theoretical grazing incidence angle indicated that the subsurface was damaged to a certain extent. The micro cracks of the subsurface were evaluated by the consistent characteristic of “peak drift” of the diffraction pattern curve in both experiments and simulations. In addition, cross-sectional TEM results showed that regular micro cracks were found on the subsurface, which agreed well with the simulation results. Conclusion The subsurface defects of CaF2 single crystals induced by abrasive machining, and the influence of micro cracks on lattice structures can be evaluated by molecular dynamics simulation. The simulation results revealed the mappings between the micro cracks and diffraction pattern curve, which demonstrated that a phenomenon of “peak drift” occurred near the diffraction angle of a specific crystal plane. This work provided a novel technology for the nondestructive testing of defects of single crystal materials at nano- and micro- scales.

Non-destructive testing (NDT) technology is a widely used inspection method for agricultural products. Compared with the conventional inspection method, there is no extensive sample preparation for NDT technology, and the sample is not damaged. In particular, NDT technology is used to inspect the internal structure of agricultural products infested by pests. The introduction and spread of pests during the import and export process can cause significant damage to the agricultural environment. Until now, pest detection in agricultural products and quarantine processes have been challenging because they used external inspection methods. However, NDT technology is advantageous in these inspection situations. In this pilot study, we investigated the feasibility of X-ray computed tomography (X-ray CT) and magnetic resonance imaging (MRI) to identify pest infestation in agricultural products. Three kinds of artificially pest-infested fruits (mango, tangerine, and chestnut) were non-destructively inspected using X-ray CT and MRI. X-ray CT was able to identify all pest infestations in fruits, while MRI could not detect the pest-infested chestnut. In addition, X-ray CT was superior to the quarantine process than MRI based on the contrast-to-noise ratio (CNR), image acquisition time, and cost. Therefore, X-ray CT is more appropriate for the pest quarantine process of fruits than MRI.

Non-destructive test (NDT) is used to find the physical properties of concrete without any destruction to the structure. There are various methods of NDT in order to calculate the strength of concrete members. Hemp is a type of agro-waste which can be used to make Hemp concrete by mixing cement, aggregates, Hemp, admixtures and water in desired proportion. The aim of the study was to correlate the Ultrasonic Pulse Velocity (UPV) with compressive strength, in order to determine equations between direct UPV with indirect UPV and to develop correlation between direct UPV with Compressive strength. In this study, 6 cubes of Hemp concrete of size 150 mm X 150 mm X 150 mm were casted and cured for 7–28 days, dried and tested for direct UPV, indirect UPV and compressive strength. Then these values are correlated with each other to determine the association in direct UPV, indirect UPV and Compressive strength. The most excellent fit curve for compressive strength and NDT values were obtained and equations were derived. These equations will be able to determine the concrete relative strength element (new or existing structural member) without destruction.

The friction stir welding and its weld properties such as tensile, micro structure of weld, grain size, and fine mixture of two alloys at to joint using testing methods. To determine the weld quality and conclude properties such as weld quality, weld strength, maximum stress that weld can withstand during operation conditions. There are various processes that involve testing the welded joint from which many are the destructive ones that are used to find the tensile strength, hardness of the joint, bending test and other tests. This paper gives an overview on how important is the fine mixture of the samples that undergo friction stir welding and how it impacts the welded sample properties. Friction stir welding creates more opportunities that are related in understanding the quality of the joint such as testing methods to increase the production by faster analysis of defects. This testing method effectively utilizes that modern computation and means to boost the production. This level of understanding creates the path to innovate new techniques to resolve industry level problems in quality control. As the non-destructive testing methods provided with no loss of the testing specimen and understanding the quality of the material after they are assembled. Such initial developments made the usage of NDT in quality control and effective results to determine the quality.

We put forward a focusing formula to describe the guided waves periodical focusing phenomenon, which, apart from being a fundamental problem in the guided waves propagation in the pipes, has essential applications in the field of nondestructive evaluation. Due to the partial circumferential loads or non-axisymmetric defects, the guided waves are not only in the zeroth-order axisymmetric forms but also in the higher-order non-axisymmetric forms. When multiple orders of the same mode exist simultaneously, the angular profile is adopted to describe the circumferential energy distribution of the superposed wave field. However, the angular profile varies in the propagation process. In our finding, this variation is periodic, meaning that the circumferential energy will repeat the process of dispersing and focusing. Thus, we put forward a focusing formula to describe the phenomenon. The proposed formula indicates that the angular profile varies periodically with the ratio of propagation distance to wave number, and this period is only related to the pipe radius. Thus, three factors, including propagation distance, excitation frequency, and pipe radius, will affect the angular profile. Moreover, we established an experimental system to verify this phenomenon, based on which we have designed three groups of experiments to investigate these three factors. The experimental results are in good agreement with the theoretical predictions.

X-ray computed tomography (CT) enables nondestructive evaluation and dimensional metrology using the reconstructed volumes of measured objects. Although the abundant applications of industrial X-ray CT exist, a high-quality reconstructed volume requires a long measurement time owing to sharp transmission images from dense views. Intensive X-rays with the exposure kept can be used to reduce the measurement time. However, the quality of the measured objects inevitably deteriorates as a result of the so-called penumbra effect caused by large focal spots in X-ray sources. This paper proposes rotational fine-tuning (RFT) for the acceleration of CT scanning with the quality kept. First, sharp transmission images from sparse views are obtained in appropriate imaging conditions. Subsequently, blurry transmission images from dense views are obtained using a larger focal spot size and a shorter exposure time. The acquired blurry images are deblurred by convolutional neural networks fine-tuned using several pairs of sharp and blurry images obtained at the corresponding projection angles, and linear interpolation integrates the deblurred images to generate the final RFT output. The proposed method indirectly reduces the measurement time because no lengthy acquisition time is required, and fine-tuning and blurring are rapid when using GPUs. In the experiments, the comparison of PSNRs between blurry and deblurred reconstructed volumes is shown. To reveal the effect of the proposed method on dimensional metrology, the improvement in the surface deviations of the stepped cylinder is also shown. Finally, the improvement of the pore spaces in a porous aluminum is shown to assess the aspect of nondestructive evaluation. Overall, experimental results demonstrate that the proposed method can perform the acceleration of X-ray CT scanning with the quality kept.

Welding is one of the join processes of any materials with usage of filler metal along with addition of heat, pressure on the surface parts. Gas Tungsten Arc welding (GTAW) is one type of joint method in which electric-arc formed and preserved amid non-consumable electrodes. the aim of this particular paper is to comparing the defects instigated of welded-Joint and mechanical behaviors such as tensile testing, bending, hardness, and impact test under various loads and conditions performing on work specimen in destructive testing. The effort of butt joints is made on stainless steels 304(SS304) plates via TIG welding apparatus the inner defects of specimens found from radiography testing in Nondestructive testing. Finally, explore the performance and conditions of TIG welded- plates after completing the work to compare radiography testing defects and mechanical properties.

Super-resolution subsurface imaging based on sparse regularization is presented in assuming the terahertz (THz) band multilayer structure analysis. The THz wave subsurface imaging with μ-scale spatial resolution and penetration depth are promising for several applications, such as nondestructive testing and chemical/biomedical compound analyses. The sparse regularization-based compressed sensing (CS) approach has considerable potential to provide super-resolution subsurface imaging in a time-of-flight estimation. However, using optical lens-based measurements, e.g., THz time-domain spectroscopic (THz-TDS) systems, a depth resolution is highly dependent on the depth of each layer, which becomes more critical in the out-of-focus case. This study demonstrated that the above depth-dependence could be solved by using an appropriate depth-dependent reference signal, by using the THz-TDS measured data.

PURPOSE: This study aims to confirm the usefulness of active acoustic emission (Active AE) for reproducible and non-invasive generation of physical external force which is required for conventional AE. METHODS: Experiment 1: A root dentin-resin adhesive interface was observed. The post space was filled with a dual-cure resin composite core material with and without adhesive. The vibration characteristics of the data obtained from the time-frequency analysis were evaluated. Experiment 2: A crown-abutment tooth adhesive interface was observed. Adhesive resin cement was used for luting the crown and adhesion states in the same specimen over time were analyzed with three measurements: at trial-fitting, immediately after luting, and 2 weeks after luting. Data were subjected to time-frequency analysis and relationships between amplitude (indicating loudness) and frequency (indicating the sound component) were analyzed. RESULTS: Experiment 1: Time-frequency analysis confirmed multiple peak frequencies for each specimen without adhesive and monomodal peak frequency in all specimens using adhesive. Experiment 2: Two weeks after luting, all specimens showed a single major peak except one which showed multiple weak peaks. The three-dimensional visualization of time-frequency analysis revealed one specimen with multiple weak peaks while all others displayed a single, low-amplitude band at 2 weeks after luting. CONCLUSION: The state of the adhesive interface can be evaluated using active AE. This basic technique may prove useful to evaluate changes in the adhesive interface of prostheses over time. ispartof: JOURNAL OF PROSTHODONTIC RESEARCH vol:66 issue:2 pages:236-242 ispartof: location:Japan status: published

The main components of concrete are cement and river sand (R-sand). Due to excessive production of cement, CO2 emission also increases which causes air pollution. On using R-Sand, large scale depletion of natural sources creates environmental problems. In view of the increasing national and global consensus on the environmental protection, the governments have put restrictions on mining of R-Sand from the river beds. To overcome these problems, there is a need of cost effective alternatives materials so as to make the construction sustainable without compromising its quality. In the production of Self Compacting Concrete (SCC), fly ash (FA) is utilized as an additional cementitious ingredient, which improves its performance. It solves the problem of FA disposal and environmental pollution too. The manufactured sand (M-sand) is also an alternative material which may solve the problem of shortage of R-Sand, if found suitable. In this study, M-Sand and FA were incorporated in the preparation of a sustainable SCC. After optimisation of FA and M-sand doses in the final mix, two types of SCC mixtures were developed: M-1, which consisted of 100% OPC + 100% R-Sand, and M-2, which consisted of 80% OPC + 20% FA + 50% R-Sand + 50% M-sand. Fresh properties of all SCCs were determined as per EFNARC/BIS recommendations. For destructive testing standard size specimens were cast to determine desired strengths after curing in tap water for 90 days. Rebound Hammer (RH) and Ultrasonic Pulse Velocity (UPV) were utilised in Non-Destructive Testing (NDT) to determine the strength, homogeneity, and integrity of both SCCs. Further, the water absorption of the specimen was measured up to 90 days. XRD analysis was also performed.

Eddy current is creating a lot of problems in high voltage and high current experiments. High eddy current can cause significant heating and deteriorating electromagnetic forces on mechanical structures. The strange behavior of eddy current will sometime leads to collapse of mechanical structures in large experimental set ups. Measurement of eddy current is very important in cases where its magnitude exceeds a certain value. Here we suggest a benchmark experiment for measuring eddy current developed on a metallic surface during a high current discharge. In this experiment, a torus shaped steel (SS 304) tube is considered which resembles super conducting reaction chamber used in fusion experiments. These experiments are under high power applications and hence the mechanical structure will be subjected to eddy current impacts which needs to be studied well in early to understand the possible after effects. Results from a benchmark experiment with similar prototype will help in such situations to derive the system parameters under actual experiment situations. Here, coil is inserted through the torus and a high current discharge is given through that coil using a capacitor and thyristor control circuit. Due to this high current discharge, eddy current will be developed on the torus surface. Practical measurement of current discharged can be calculated using a calibrated Rogowski coil. Another calibrated Rogowski coil is wound across the torus structure to pick the eddy current. Rogowski coil will give the di/dt value. Integrating the output will give the value of current. Subtracting the two Rogowski coil output will give the eddy current value. Further, the experimental set up is modeled and simulated in ANSYS MAXWELL and eddy current obtained from simulation is compared with those we obtained practical values. The proposed experimental setup is a Non Destructive Test (NDT) and therefore this can be easily executed in any test atmosphere. The validated method finds its application in particle accelerators and fusion research.

High field pulsed magnets at the NHMFL use high strength conductor wires up to 90% of their ultimate tensile strength. Therefore it is very important to ensure that the wires are free of flaws. It is known that in the conductors cold drawing process, internal chevron crack could occur due to unsuitable drawing die schedule or inadequate lubrication. These internal cracks occurs infrequently along the wire, so tensile tests of short samples cut from the ends of a long length conductor often miss the problem. In addition, small inclusions on the wire surface can compromise wires fatigue properties. In this paper, we present results of our non-destructive testing (NDT) inspection of Glidcop AL60 wires using eddy current testing (ECT), ultrasonic testing (UT) and x-ray radiography (2D and 3D). Chevron cracks were found in some AL60 conductors by all three NDT techniques. Surface inclusions were found by ECT. We have developed a long length ECT wire inspection capability., 4 pages, 9 figures

Based on localized spoof surface plasmons (LSSPs), a new microwave nondestructive testing (NDT) sensor is proposed to measure the thickness of magnetic absorbing coating on metallic surface. The metallic spiral structure (MSS) sensor fed by microstrip ring generates the LSSPs, which is used to interact with material under test (MUT) and measure the thickness of MUT. Through measurement mechanism and numerical analysis, the magnitude of the reflection coefficient is sensitive to the thickness variation of the coating. Taking a kind of magnetic absorbing film A4000 as an example, the experimental results reveal that the MSS sensor can estimate the film thickness with a range of 0.05-1.03mm, and the error is within 6%. The highest resolution can reach 0.05mm in the experiment. In fact, the formula shows that the highest resolution can reach 0.01mm. Compared with conventional monopole antenna, the microstrip ring is a new way to feed the MSS, which makes the sensor structure more stable and more compact. The sensitivity of the sensor is improved by using electric field and magnetic field to interact with the MUT together. The sensor has the advantages of high resolution, small error, stable performance and no limit to the size of the MUT.

Crack orientation is a vital factor in the behavioral study of fractures, especially the study of crack propagation in structures that are under dynamic or fatigue loading. Indeed, many non-destructive testing (NDT) techniques have been developed recently for the detection of cracks such as the eddy current testing (ECT). However, the crack orientation has not been undertaken into consideration. In this paper, a NDT based on eddy current using 3D finite element modeling, is proposed for the determination of the crack orientation. The idea of this proposed technique benefits from the influences of crack orientation, which can be observed on the components of eddy current and the related magnetic flux density following the x, y axes, for the estimation of the crack angle orientation based on an interpolation criteria. The obtained results through the presented simulation prove the validity of the proposed technique for the detection of crack angle orientation.

Inadvertently and intentionally incorrect welding films are very common in X-ray non-destructive testing (NDT) of welding engineering. The forgery welding films were handed in by welding workers and pretended these films were X-ray photographed on the welding seams that need to be inspected, but actually, these films were X-ray photographed on other welding seams that are of high quality and had passed the X-ray imaging inspection. If some welding seams escape inspection due to forgery, these will cause many potential safety hazards. The current forgery detection method is manual inspection, which is very time-consuming and laborious. An automatic forgery detection method for X-ray non-destructive testing of welding was proposed. Three solutions were used to prevent forgery: they were the markers recognition for avoiding erroneous submission, the fingerprint extraction for identifying welding seam uniquely, and the overlap matching for preventing intentional forgery. This paper proposed a concept of welding seam fingerprint. The welding seam features were extracted based on an improved SPP-net deep learning model. Those deep learning features of welding seam were called as the welding seam fingerprint. The proposed method can automatically accomplish the forgery detection, which can greatly reduce the workload of manual detection and make the welding inspectors focus their attention on the welding defects inspection rather than on the forgery prevention.

This study aims to combine the smart pigs as a non-destructive test (NDT) inspection technique with software developed for the assessment of pipeline corrosion defects to ensure fitness for the surface. The software uses decision support systems, connected through the correlated linkage technique, which is coded using Microsoft Access and Visual C#. This software measures general internal pipeline corrosion forms to identify locations with potential corrosion features and predict corrosion conditions in the future. Computer-aided corrosion management program (CACM) examined maximum corroded depth of internal corrosion, maximum allowable axial corrosion defect length, failure pressure, the corrosion rate, and the remaining pipeline life. This work introduces a wide-ranging review of computer-aided corrosion management programs. The proposed method of assisting and detecting corrosion internal defects and defects data should be available. This software is easy to use without complicated analysis. It helps to reduce unplanned shutdowns in the oil and gas production industry.

Nondestructive testing (NDT) methods are widely used in the rail industry to detect and characterize rolling contact fatigue (RCF) defects in railroads, which is very important for railway inspection and maintenance to prevent catastrophic accidents. Existing NDT methods, e.g., ultrasonic testing (UT), magnetic flux leakage (MFL), and eddy current testing (ECT) have been successfully applied in the rail industry, and the state-of-the-art UT method reported recently achieved a high speed of 40 mi/h with a probability of detection (POD) over 80% under 30% false alarms. However, NDT methods still suffer from a bottleneck in that a higher inspection speed causes lower detection sensitivity due to their physical limits, such as negative velocity effect and long sensing time. One of the leading challenges to the rail NDT community is to develop a high-speed high-sensitivity (HSHS) capability that can provide an improved POD of rail defects in high-speed inspection scenarios over 60 mi/h. This article proposes a horizontal U-shaped magnets-based motion-induced eddy current array (MIECA) method to detect rail surface defects with the HSHS capability. The MIECA method deploys a three-axis magnetic sensor array along the rail transverse direction at the middle of the magnets to measure the MIECA signals, which utilizes the wake effect of the diffused motion-induced eddy current (MIEC) caused by the relative high-speed motion between the magnets and the rail track. Finite-element method (FEM) simulations with a wide speed range from 0 to 62.5 mi/h are carried out to investigate the relationships between the MIEC generation, diffusion and magnitude, and the three-axis MIECA signals. The simulation results show that the higher the speed, the greater the magnitude of diffused MIEC, and the greater the peak-to-peak values of three-axis MIECA signals caused by rail surface defects, which shows a great promise for detecting rail surface defects in high-speed scenarios and is superior inspection relative to existing NDT methods in terms of inspection speed, detection sensitivity, and defect characterization capability.

Relevance. To ensure the safety of a nuclear power plant on the basis of the requirements of norms and rules in the field of the use of atomic energy for pipelines of the primary circuit of a nuclear reactor, the design should apply the leak before break concept. The main idea of the concept is to prevent a sudden rupture of the pipelines of the reactor coolant loop, and consists in substantiating the fact that the rupture is preceded by the formation of a stable through crack, which is detected by the provided leak control means. When substantiating the concept, it is assumed that break without leak is an impossible event. This article provides a method for determining the probability of a failure event without a leak. Purpose - estimate the probability of the existence of a defect that can lead to the destruction of the vessel or pressure pipeline without leakage, as well as the probability of failure without leakage for a known number of loading cycles. Methods. To systematize the data obtained by different methods of non-destructive testing, conservative assumptions were used to determine the area of detected defects. On the basis of the obtained defect sizes, the defect size regions were determined, which can determine the scenarios of crack growth. Using the methods of mathematical statistics, the probability of the existence of a defect, which can lead to failure without leakage, was determined. Based on the methods of the theory of reliability, a comparison of the obtained probability of destruction with the admissible value is carried out. Results. A method for processing non-destructive testing data based on an assessment of the area of detected defects has been developed to systematize the data obtained by different non-destructive testing methods. The criterion for the development of cracks according to the scheme leak before destruction is determined. A method has been developed for determining the probability of a defect that can lead to failure without leakage. An example of calculation based on feed water pipelines is considered.

With the rapid development and application of the laser ultrasonic technology in nondestructive testing in recent years, thermo-elastic waves in diverse waveguides have captured a multitude of attention. However, they are mainly focused on one-dimensional and half-space structures. In engineering, there are also a lot of two-dimensional structures, such as joist steel, straight bars and rings. However, rare attention is paid on thermo-elastic waves in these structures. Accordingly, in the context of Green–Lindsay (G–L) generalized thermo-elasticity theory, a modified double orthogonal polynomial approach is exploited to investigate thermo-elastic waves in bars with a rectangular cross-section. The dispersion, attenuation and displacement curves of thermo-elastic waves are illustrated. Subsequently, influences of the cross-section size and relaxation time on wave characteristics are analyzed. Results indicate that the cross-section size and relaxation time have a significant influence on thermo-elastic waves. The phase velocity and attenuation values of thermal wave modes decrease as the relaxation time increases. These results obtained can be utilized to guide the laser ultrasonic nondestructive testing for this kind of structures.

Insulating joint is an essential component for pipeline cathodic protection system. During the safety confirmation before the excavation of the station foundation pit, a pipeline company found that the insulating joint was failed due to leakage. In order to determine the causes of leakage, data verification, tests and failure component analysis were carried out. The results show that: (1) the leakage point cannot be detected by NDT, hydraulic pressure test, and hydraulic pressure + bending test, and the gas leak test in the water container demonstrates two leakage points on the fixing sleeve of the insulating joint; (2) the insulating joint has an unfilled cavity, and the mechanical holes on the fixing sleeve are blocked by bolts, which are inconsistent with the assembly drawing; and (3) the leakage of the insulating joint was caused by the sealing failure during assembly or service, which allowed some gas to gather in the cavity between the flange and the fixing sleeve and then leak through the gap between the mechanical hole and the bolt. Accordingly, it is suggested that (1) manufacturers should strictly follow the process when producing insulating joints, the product structure be consistent with the assembly drawing, the product inspection be done according to requirements, and NDT be done on all welding areas; and (2) the insulating joint be leak-tested in the water container where possible.

In this paper, eddy current thermography is used to detect metal in wood materials, and thermal signal reconstruction (TSR) algorithm has been proposed to solve the problem of low resolution of metal detection. The basic principle of current nondestructive testing technologies for wood materials has been briefly reviewed, and the advantages and disadvantages have been analyzed. TSR algorithm can significantly enhance the contrast ration between metal and surrounding areas, different quantities of metal can be effective identified, and metal positions can be accurately realized. The experimental results show that the proposed eddy current thermography technology can quickly detect metal in wood materials and improve the efficiency and accuracy. The size and quantity of metal can be intuitively observed through thermal images.

During the laser additive manufacturing (LAM) process large temperature gradients can form, generating a mismatch in deformation that can lead to high level of residual stress. The stress can have irreversible effects such as warping and cracking of parts during and post manufacturing. One of the most important LAM parameters that should be controlled carefully in order to effectively manage residual stress is the scanning strategy. This study presents an evaluation of six different scanning strategies, namely reciprocating, 90° reciprocating, line, screwing, reciprocating overlapping and island scanning strategies with respect to their effect on residual stress. Laser ultrasound technology, as an advanced nondestructive testing method, is applied to measure the residual stress distribution under different scanning strategies for the first time. The surface wave generated by laser is used to evaluate the plane stress state within the surface layer of the specimen. The results show that the island scanning strategy is found to contribute to the least average residual stress, and lowered residual stress by up to 45% relative to the line scanning strategy. The overall stress level is island

This paper presents the feasibility of developing an electromechanical in-situ viscosity measurement technique by analyzing the detectability of small variations in the viscosity of different shear thickening fluids and their different compositions. Shear thickening fluid (STF) is a kind of non-Newtonian fluid showing an increasing viscosity profile under loading. STF is utilized in several applications to take advantage of its tunable rheology. However, process control in different STF applications requires rheological measurements, which cause a costly investment and long-lasting labor. Therefore, one of the most commonly used in-situ structural health monitoring techniques, electromechanical impedance (EMI), was used in this study. In order to actuate the medium electromechanically, a piezoelectric wafer active sensor (PWAS) was used. The variations in the spectral response of PWAS resonator that can be submerged into shear thickening fluid are analyzed by the root mean square deviation, mean absolute percentage deviation and correlation coefficient deviation. According to the results, EMI metrics provide good correlations with the rheological parameters of STF and thereby enabling quick and low-cost rheological control for STF applications such as vibration dampers or stiffness control systems.

The damage diagnosis of traditional hydraulic engineering structures is largely based on the modal analysis of contact approach, which makes it difficult to carry out a rapid diagnosis of the damage following an earthquake. In view of enhancing the efficiency of water conservancy engineering damage detection, this study was aimed at improving the traditional ant lion optimizer algorithm, combining it with wavelet transform to detect image denoising and effectively extract the features of the damage. Meanwhile, in terms of signal transmission and collection, the study adopted a geological radar as the carrier. In addition, the study verified the application prospects of nondestructive testing technology in the field of water conservancy engineering by evaluating the quality of a specific water conservancy project. Finally, the effectiveness of the algorithm was analyzed via experimental research. The results demonstrate that the proposed algorithm has clear advantages over traditional detection techniques.

Pulsed eddy current (PEC) is an electromagnetic non-destructive testing (NDT) technique mainly used to inspect corrosion in pipelines. Like many other NDT techniques, to quantify pipe wall thickness, a signal feature has to be extracted from the PEC response. The authors’ previous work has exploited the linear relationship of the time-derivative feature to propose an in-situ calibration routine. However, to extract the time-derivative feature, two configuration parameters need to be determined prior to feature extraction. To the authors’ knowledge, none of the previous works explores the determining factors of this configuration parameters, where the current technique is still limited to using brute force method or trial-and-error. This paper brings novelty by formulating the aforementioned problem as a minimisation problem, and solving it using a particle swarm optimisation (PSO) algorithm. The obtained results, compared against brute force method, demonstrate the feasibility and performance improvement of using PSO in determining the configuration parameters. The approach thus presented is validated and the results obtained are justified by analysing the underlying physical system theory.

Introduction. X-ray inspection plays a unique role among all nondestructive testing methods for products and materials due to sufficiently high resolution and high penetrability. The present study is designed to consider the key features of microfocus X-ray sources, their areas of application, and main technical characteristics.Aim. The paper aims to systematize information and review modern X-ray radiation sources for the implementation of microfocus radiography.Materials and methods. The main designs of microfocus X-ray tubes (soldered and demountable) were considered relying on the experience of the St Petersburg State Electrotechnical University in developing and operating such equipment, as well as the experience and open-access publications of foreign researchers and developers. Data collected by leading research teams over the last ten years were analyzed.Results. The paper presents design features for each main type of microfocus X-ray tubes – soldered and demountable. All key structural elements are considered: an anode assembly, a cathode assembly, and a focusing system. The influence of anode target material on the X-ray tube radiation spectrum is shown. An original design of a liquid-anode microfocus X-ray tube is described to demonstrate its key features and advantages. In addition, the paper gives an overview of cathodes used in microfocus X-ray tubes (tungsten cathode and lanthanum hexaboride cathode), as well as providing a detailed description of calculations performed for focusing systems. Finally, the designs of modern X-ray tubes are presented.Conclusion. Modern X-ray tubes are high-tech products that allow for high-resolution research of various objects. The main advantage of testing performed with the use of X-ray tubes consists in high resolution (micron and submicron). The X-ray images of test objects used to determine their spatial resolution are given, which clearly illustrate the vast possibilities of this technology. In addition, ways to improve microfocus X-ray tubes are briefly discussed. The considered materials can be useful in selecting a nondestructive testing tool, as well as in developing and creating X-ray systems on the basis of microfocus X-ray tubes.

The influence of ongoing cement hydration and multiple microcrack formation on the electrical impedance of an engineered cementitious composite (ECC) is presented. Impedance measurements were obtained over the frequency range 20 Hz–1 MHz and displayed in the Nyquist format. In addition, the permittivity and conductivity were de-embedded from the measured impedance and presented in both time and frequency domains to elucidate the nature of conduction and polarisation processes. It was found that, over a curing period of 90 days, the ECC displayed a classic impedance response. Both conductivity and relative permittivity were found to be frequency dependent due to bulk relaxation processes operating within the composite. Tensile straining was shown to result in a detectable change in the impedance response, but retained a similar overall profile. When presented in the frequency domain, a downward displacement in both conductivity and relative permittivity profiles was evident with increasing tensile strain. It is shown that the relative permittivity at the high-frequency end could be exploited as a potentially useful indicator for strain/damage detection. The influence of microcracking on the piezo-resistive response of the composite is discussed based on crack patterns obtained from both visual observations and digital image correlation.

Flexible pipes are complex structures made of different layers and different materials. They are used in the oil and gas production in the off-shore platforms to conduct the oil or gas between different units, such as platforms, Christma's tree and transportation ships. The internal carcass of flexible pipes is made of duplex stainless steels type 2205 (UNS S32205 or S31803). In the production line, sheets of 1.8 mm thickness of this material are submitted to uncoiling and cold bending operations to form “S” profiles which are assembled to form the internal carcass. The end of one coil is welded to the begin of another, to make the process continuous. The welding process is autogenous automatic gas tungsten arc (GTAW). This work analyses the microstructure and corrosion resistance of the weld metal and compares to the base metal. Besides, non-destructive tests and electrical resistance measurements were conducted in the welded joint and base metal. The samples analyzed were from a flexible pipe manufacturer. It was concluded that the joints of this producer were not heat treated, which results in inadequate microstructure and lower corrosion resistance in the weld metal.

This paper studies the method of determining the fracture parameters of pre-notched concrete beams with horizontal pre-set cracks and the influence of fracture intersection on fracture characteristics of concrete based on the three-point bending test. Pre-notched concrete beams with horizontal pre-set cracks were designed as 13 groups according to the different positions, lengths and widths of horizontal pre-set cracks. The fracture toughness was calculated on the basis of the cohesive force model of concrete, and the crack opening displacement obtained by using the digital image correlation technique. The study's results indicate that the distance between the pre-set crack and the notch tip as well as the pre-set crack length and width have various influences on the fracture propagation of edge mode I crack, the bearing capacity and unstable fracture toughness of concrete beams owing to varying degrees of loss of cohesion in the fracture process zone (FPZ). The study also finds that a large lack of cohesion in the FPZ indicates a high possibility of a reduction in the bearing capacity and unstable fracture toughness of concrete beams.

We combine three different approaches to greatly enhance the defect reconstruction ability of active thermographic testing. As experimental approach, laser-based structured illumination is performed in a stepwise manner. As an intermediate signal processing step, the virtual wave concept is used in order to effectively convert the notoriously difficult to solve diffusion-based inverse problem into a somewhat milder wave-based inverse problem. As a final step, a compressed-sensing-based optimization procedure is applied which efficiently solves the inverse problem by making advantage of the joint sparsity of multiple blind measurements. To evaluate our proposed processing technique, we investigate an additively manufactured stainless steel sample with eight internal defects. The concerted super resolution approach is compared to conventional thermographic reconstruction techniques and shows an at least four times better spatial resolution.

X-ray computed laminography (CL), as a popular nondestructive testing technology, has unique advantages for the detection of plate-type structures. However, with the limitation of the detector size, the specimen, i.e., large flat-like components, may be beyond the field of view (FOV) of the CL system. For the cone-beam computed tomography (CBCT) system, which is analogous to the CL system, a traditional way to enlarge the FOV is the displaced sample stage scanning mode. In this article, a new CL reconstruction method with the displaced sample stage scanning mode is proposed to enlarge the FOV of the CL system. According to this method, a virtual detector is established to obtain a new CBCT system under the displaced sample stage. Then, the projection data are converted into the virtual detector and scanning geometric parameters are calculated. The Feldkamp–Davis–Kress (FDK) algorithm combined with the Parker weighting function can well reconstruct the cross sections of the specimen with acceptable quality. The numerical simulation and experiments demonstrate that the proposed approach can achieve image reconstruction with sufficient quality and low computational cost. The FOV of the CL system is enlarged effectively without changing the original scanning geometry, and thereby, it can be conveniently utilized in engineering applications.

Development of a nondestructive evaluation (NDE) method to detect nascent hydrogen embrittlement (HE) in electroplated high-strength steel parts is becoming important for the aerospace industry. This research investigates the feasibility of surface acoustic waves (SAWs) measurements to distinguish between cadmium (Cd) plated SAE 4340 steel samples with low and high HE susceptibilities. SAWs were generated with a 10 MHz piezoelectric transducer and detected by line scans via a laser Doppler vibrometer setup. Using signal processing algorithms in MATLAB, SAW velocities as well as attenuation coefficients were estimated. Depth profiles of steel hardness near coatings were also evaluated using Vickers microindentation tests. Average steel hardness in not-baked samples was slightly increased. Cd coatings were characterized by laser and optical microscopy methods. Small variations found in thickness and surface roughness of the Cd coatings among the samples did not significantly affect the NDE results. On average, samples in the not-baked condition (high HE risk) exhibited lower SAW attenuation coefficients compared to immediately baked and late-baked conditions (low HE risk). However, it was not possible to distinguish between the manufacturing conditions of individual samples due to overlaps in attenuation measurement results. SAW velocities as estimated by the cross-correlation method were found to be not sensitive to manufacturing conditions.

In this paper, we study the accuracy and robustness of the computational time reversal approach based on the explicit finite element method for application in nondestructive testing in solids. The main goal of this paper is to find a methodology for correct and accurate reconstruction of the original source time history. For numerical modeling of frontal (forward) and reverse (backward) problems of elastic wave propagation, we use the finite element method and explicit time integration with the lumped mass matrix. The suggested methodology is applicable in each finite element open source or commercial software. A special attention is paid to prescription of boundary conditions/loading for the reverse problem for accurate reconstruction of time history of the original source. For evaluation of the reconstruction quality, we suggest certain cost functions. Based on several numerical tests, we show effects of prescription of boundary conditions/loading in time reversal, effect of mesh size and time step size, an unknown obstacle, a number of sources, and environmental disturbance (noise) on the correctness of reconstruction of the original source.

Out-of-plane waviness is one of the most common defects which degenerates the strength, stiffness, and fatigue life of hybrid glass–carbon fiber–reinforced polymer composites (FRPs). An accurate and high-speed non-destructive testing method is highly desired for large composite structures in industries. Ultrasonic phased array is a great candidate for such application. This paper applies the wavenumber algorithm to image the waviness in hybrid FRP plates which are a multi-layered medium. The central frequency of 5 MHZ is chosen in order to maximize the ply resonance. Transducers are migrated virtually to each interface between glass and carbon plies in order to overcome the difficulty of wave propagation analysis in such multi-layered system. The wavenumber algorithm demonstrates a better computational performance compared to that of the traditional total focusing method (TFM) in time domain up to 6 times. The glass ply depth and waviness angle can be more accurately presented with relative errors less than 1.5% and 14.8%, respectively. In addition, the resin-rich defect characterization is also achievable with a maximum error of 14.4%.

In this study, the electrical resistivity measurements as an accessible technique for NDT inspection of FSWed sections were investigated. For this purpose, 1080 Aluminum plates were welded by the F...

Particle clogging in the artificial groundwater recharge process is one of the main factors influencing the artificial groundwater recharge efficiency, and particle deposition is the microscopic mechanism of the occurrence and development of particle clogging. Particle deposition in porous media changes the pore structure. The computed tomography (CT) scanning technique is a nondestructive testing method and determines the spatial distribution of pores in porous media. This study combines physical and CT scanning experiments to identify the change process of the pore structure in the artificial groundwater recharge process and compares the pore changes during recharge experiments between two columns containing different media. Porous media changes are observed with the CT scanning technique. The fractal theory is applied in the analysis of CT scan images and physical experiment results. The results of this study indicate that particle deposition can be examined by using CT scan images to obtain pore-related parameters, the internal pore structure of porous media determined through CT scan images can be applied in numerical simulation, and a mathematical model for particle deposition calculation in porous media is established. Compared to the physical experiment measurements, the spatial particle deposition information acquired with the CT scanning technique exhibits a higher accuracy and contains much more relevant data. Not only does this research reveal more clearly the particle clogging mechanism which is based on particle deposition, but also characterize, simulate and predict more accurately the development tendency of particle clogging during artificial groundwater recharge.

Purpose In eddy current nondestructive testing, a probe with a ferrite core such as an E-core coil is usually used to detect and locate defects such as cracks and corrosion in conductive material. However, the E-core coil has some disadvantages, such as large volume and difficulty in the process of winding the coils. This paper aims to present a novel T-core probe and its analytical model used for evaluating hidden holes in a multi- layer conductor. Design/methodology/approach By using a cylindrical coordinate system, the solution domain is truncated in the radial direction. The magnetic vector potential of each region excited by a filamentary coil is derived, and the expansion coefficients of the solutions are obtained by matching the boundary and interface conditions between the regions. By using the truncated region eigenfunction expansion method, the final expression in closed form for the impedance of the multi-turn coil is worked out, and the impedance calculation is performed in Mathematica. For frequencies ranging from 100 Hz to 100 kHz, both the impedance changes of the T-core coil above the multi-layer conductor without a hidden hole and in the absence of the layered conductor were calculated, and the influence of a hidden hole in the multi-layer conducting structure on the impedance change was investigated. Findings The correctness of the analytical model of the T-core coil was verified by the finite element method and experiments. The proposed T-core coil has higher sensitivity than an air-core coil, and similar sensitivity and smaller size than an E-core coil. Originality/value A new T-core coil probe and its accurate theoretical model for defect evaluation of conductor were presented; probe and analytical model can be used in probe design, detection process simulation or can be directly used in defect evaluation of multi-layer conductor.

Several methods have been used to detect defects or debonds nondestructively in materials or construction. Each of these nondestructive testing methods has advantages and limitations. Generally, they are suitable for testing a certain range or a specific type of material and structure and some of them require careful analysis to identify the features of the defects. The present work proposes a nondestructive testing method based on electro-acoustic technique (NDTPEA) to detect internal defects of dielectric materials, which can identify the defects from the original stress wave generated at the internal defect surface. Electric polarization occurs in the dielectric under the action of a high-voltage electric field. When the intensity of the electric field changes suddenly, the polarization charge generates a stress wave. If there are defects, such as cracks and debonding, in the medium, the position and size of the internal defects of the insulating material can be determined according to the stress wave. The waveform and velocity of stress wave is measured by a PVDF film. According to the velocity and time of the stress wave in the dielectric, the position of the internal defects or debonding of the specimen can be determined. The maximum error for measuring the wave transmission time is 1 ns, and the maximum measurement error in the defect thickness direction was 0.00253 mm. In the NDTPEA, the detected wave originates from the vibration of the polarized charge at the defect, i.e., the defect is the source of the stress wave. The measured stress wave does not undergo any reflection or refraction, and the waveform is truly regular, without coupling factors. The wave shape and time characteristics can all reflect the characteristics of the defects.

The microstructure-sensitive acoustic parameters (MSA parameters) of metal of the object under control are determined using measurements of the propagation time of bulk elastic waves of the ultrasonic range by the echo-pulse method. The structural features of the metal are thus evaluated not only in the surface layer, but also throughout the entire volume. We present the results of practical application of the MSA-parameters to estimation of the deviation of the velocity ratios of longitudinal and shear waves relative to the «basic» state with known strength characteristics. A correlation of the MSA-parameters with variations in the elastic moduli of metals attributed to modification of their microstructure is discussed. The generalized values of the ratios of wave velocities for steels of the same group are used in calculations to characterize the «base» state. It is shown that when calculating the MSA-parameters for a certain kind of construction steel, it is possible to use the averaged ratios of the velocities measured for quasi-isotropic reference samples made of the same type of steel. The generalized baseline ratios of the longitudinal and shear wave velocities are determined for the samples made of carbon steel, low-alloy, and alloyed steels. We present experimental evidence of using MSA-parameters to detect microstructural changes in metal samples and accompanying changes in their strength characteristics that occur during changes in modes and conditions of welding and heat treatment. A comparative analysis of the MSA parameters with the values of the mechanical properties and parameters of the crack resistance of the metal is carried out. It was shown that the accuracy of measuring the MCA parameters provided by modern hardware significantly exceeds changes in them occurred under significant deviations of the strength characteristics. The experimental results obtained clearly indicate that the MSA-parameters can be successfully used to improve the methods of quantitative non-destructive assessment of the features of metal microstructures