Journal of Nondestructive Evaluation最新文献

Accurate 3D mesh registration is essential in many industrial applications of X-ray imaging, as it allows quality assessment and inspection of manufactured objects. Conventional methods rely mainly on time-consuming and expensive X-ray computed tomography (X-CT) or ancillary camera systems. Instead, we propose a novel approach for efficient 3D multi-mesh registration in few-view industrial X-ray imaging scenarios. Our approach harnesses the capabilities of CAD-ASTRA, an X-ray mesh projector, compatible with the ASTRA toolbox and popular GPU libraries such as CuPy and PyTorch, for the simulation of X-ray projec tions from a known object surface mesh. As a differentiable program, CAD-ASTRA allows iterative improvement of the objects’ position in space by back-propagation of a differentiable measure of the projection error. The potential of this approach is demonstrated through tests on simultaneous multiple object registration in a poly-chromatic imaging, even in cases where the spectral characteristics of the imaging system are unknown. Results from a diverse set of real experiments highlight the efficacy of mesh registration, achieving successful registrations even when only two projections at a 10(^circ ) angle relative to the scanning system center are available. The mesh projector facilitates resource-efficient registration in industrial applications with few viewpoints, thereby reducing the demand for resources and eliminating the need for X-CT reconstruction.

The identification of cross-sectional loss in cables due to corrosion is crucial for evaluating the remaining strength of bridge cables. To accurately determine the cross-sectional loss rate, this paper derived a three-dimensional magnetic dipole model for spatial cable damage. The study employed an independently designed self-magnetic flux leakage (SMFL) sensor array to detect corrosion on a bundle of 37 parallel steel wires. The analysis investigated the correlation between corrosion degrees and SMFL signal features. The results show that the spatial magnetic field inversion collected by the sensor array device is more accurate. The cable damage location can be pinpointed by observing abrupt changes in the B_x and B_z curves. Additionally, this paper introduces five corrosion characterization features, all correlated with the cable cross-sectional loss rate. However, recognition stability using a single characteristic value is insufficient. The cable cross-sectional loss rate identification method, utilizing a back propagation neural network in conjunction with multiple characteristic indicators, demonstrates robust quantitative and adaptive capabilities. The maximum relative error of this method is 7.6%, offering a new perspective for future cable damage detection.

This work presents the details of experimental investigations to study the effects of surface roughness on adhesive joints’ strength and establish a correlation with corresponding Nondestructive Evaluation (NDE) parameters. NDE parameters are the quantifiable properties of specimens that NDE techniques can measure. The roughness at Single Lap Joint (SLJ) interfaces was varied using different emery grades of 36, 50, 60, and 80 CAMI scale. The change in roughness was evaluated through NDE tools viz., X-ray radiography testing (XRT), Acoustic Wave Propagation, and InfraRed Thermography (IRT). While X-ray images do not show any significant variation in intensities with roughness, roughness can be visualized after histogram equalization. The change in image intensities was observed with adherend thickness. The attenuation coefficient of acoustic waves for joints with different grades of roughness evaluated using the standard Hsu-Nielsen pencil source through pitch-and-catch method shows a correlation with the surface roughness. IRT shows the variation in the cooling constant with roughness and thickness of the adherends. This paper also demonstrates the thermal conductivity evaluation of the bonded specimen with IRT and the effect of surface roughness on it. The destructive tests evaluated the shear strength, and the NDE parameters were correlated with the shear strength of the SLJ.

Period-permanent-magnet (PPM) electromagnetic acoustic transducer (EMAT) has been widely used in shear horizontal (SH) ultrasonic guided wave testing owing to its advantages, such as non-contact coupling, and convenient to excite SH waves. However, its poor transduction efficiency leads to weak signals and limits the lift-off performance. This article investigates how to improve the signal amplitude by adjusting the number of turns of the racetrack coil. The inductive coupling process of the PPM-EMAT receiver is first studied using the equivalent circuit method, and the corresponding equivalent model is obtained. Aiming at the effects of coil configurations, the equivalent impedance parameters of multilayer racetrack coils are analyzed by calculations and measurements. The proposed model can be used to predict the receiving frequency response of PPM-EMAT receivers with different coil structures, and it has been verified experimentally. It can be obtained that by choosing an appropriate coil configuration and matching resistance, the SH wave signal amplitude can be increased by 3 times.

The major objective when applying non-destructive testing (NDT) in civil engineering is the detection of defects such as honeycombs. Defects can impair the service life of structures and could lead in the worst case to fatal failures. All structures such as bridges, tunnels, locks etc. are unique objects with variation in geometry, dimensions, materials, environmental condition, load scenarios etc. Thus, the interpretation of NDT data is challenging and the validation of the NDT method, the training of inspectors and the reliability analysis of NDT rely on mock-ups with known defect situations mimicking the type of defect as realistic as possible. The considered defect sizes inside the mock-ups should cover the transition zone between detectable and non-detectable to properly evaluate the capability of the inspection system. However, knowledge about the limits of an inspection system is mostly non-existent. To overcome this limitation, this study applies realistic numerical simulations for ultrasonic testing in reinforced concrete performed with the elastodynamic finite integration technique (EFIT) to identify this transition zone. First, the study shows the development and the validation of a numerical representation of concrete considering the implementation of a qualitatively realistic noise level. Additionally, the accurate representation of the sources during ultrasonic testing is confirmed by an investigation of the radiation characteristic for dry point contact ultrasonic transducers. The simulation outcome enabled the design of a mock-up, which explores the detection limits for honeycombs during ultrasonic testing under different boundary conditions. A case study demonstrates the applicability of the design scheme based on numerical simulation. In the real specimen designed with the assistance of numerical simulations, (68mathrm{%}) of the implemented defects are detectable, proving the effectiveness of the design methodology.

In order to understand the delamination growth under mode II loading from the perspective of composite damage mechanisms, this study conducted in-depth research on the damage evolution of laminated plates using acoustic emission (AE) technology and signal analysis methods. Delamination mainly includes two stages: initiation and propagation, in which the initiation is the more important stage in the process of material delamination. Three damage modes of laminated materials during loading were identified by combining peak frequency statistics of AE signals with continuous wavelet transform (CWT). The initial time and stage of delamination can be determined by two methods. (1) The evolution process of damage mechanisms can be characterized by the fast fourier transform (FFT) of AE signals in several time periods. (2) The cumulative energy of three damage modes separated by variational mode decomposition (VMD) can be used to characterize the damage evolution process. The initial time determined by integrating several methods is much earlier than the occurrence time of the interlaminar fracture toughness value defined by ASTM standard. The strain energy release rate (SERR) determined at the initial time of delamination is taken as a design reference, which will be of guiding significance for ensuring the safety of laminates.

The paper deals with the non-destructive experimental testing of the reinforced concrete beams under progressive corrosion. A series of experiments using electrical potential, ultrasound and low-frequency vibrations techniques are reported. Electrical potential and natural frequencies were used to characterise and monitor the corrosion process at its initial state. The P-wave velocity measurements were proved to be effective in quantitative assessment of the level of corrosion as it progresses. The possibility of early detection of damage using a proposed damage index and diagnostic framework is promising for possible applications in the non-invasive diagnostics of reinforced concrete elements.

The extension of conventional computed tomography known as spectral computed tomography involves utilizing the variations in X-ray attenuation, driven by spectral and material dependencies. This technique enables the virtual decomposition of scanned objects, revealing their elemental constituents. The resultant images provide quantitative information, such as material concentration within the scanned volume. Enhancements in results are achievable through methods that capitalize on the strong correlation among decomposed images, effectively minimizing noise and artifacts. The Rigaku nano3DX submicron tomograph uses a dual-target source, which allows the generation of two distinct X-ray spectra through different target materials. This configuration holds promise for high-resolution applications in spectral tomography, particularly for low-Z materials, where it offers high contrast in the acquired images. The potential of this setup in the context of spectral computed tomography is explored in this contribution, delving into its applications for materials characterized by low atomic numbers.

In the present paper, magnetic Barkhausen noise (MBN) measurements have been carried out to evaluate the hardness and ferrite grain size of API X70 steel. All samples were austenitized at 900–1200 °C for 0.5 h followed by air-cooling identically to develop different ferrite grain size. The microstructure examinations were determined by Scanning Electron Microscope (SEM). The average ferrite grain size in each sample was estimated using ImageJ open-source software. Hardness measurements were performed using durometer device. Measurements of MBN were conducted using MikroMach (Micromagnetic Materials Characterization) system. The microstructure observation shows that the increase in the austenization temperature (AUT) causes an increase in the ferrite grain size as well as their change in shape from polygonal to acicular. The results of mechanical tests showed that the increase in the austenization temperature leads to an increase in the hardness of the X70 steel. Actually, MBN method can be used to evaluate the changes in hardness and ferrite grain size in ferromagnetic materials. The sample with the lowest austenitic temperature has the highest Barkhausen noise amplitude (BNA); in contrast, the sample which contains the highest austenitic temperature has the lowest BNA; furthermore, when the austenization temperatures increases, the signal of the coercive field Hc shifts to the higher values of magnetic field. Additionally, BNA decreases, and Hc increases whenever hardness and ferrite grain size increases. In this way, a good correlation was found between MBN parameters, ferrite grain size, and hardness values. The realized experimental setup can be used for online evaluate steel microstructures and quality control of ferromagnetic materials in some industrial applications.

Millimeter wave operates within a wavelength range of 1mm to 10mm and can penetrate through various non-metallic materials, such as the paperboard and plastic films commonly used in cigarette packaging boxes. In comparison to X-ray devices, millimeter wave imagers have the added advantage of not emitting ionizing radiation and having lower electromagnetic radiation output than the standard limit for mobile phone. Given these characteristics, we believe that utilizing millimeter wave imaging technology for detecting missing carton in packaged cigarette boxes could be a viable solution. The paper presents the fundamental imaging theory and showcases some images of cigarette boxes. The results demonstrate that our millimeter wave imager can produce clear images of packaged cigarette boxes with missing carton. We anticipate that this system has significant potential for application in machine vision for tobacco and other similar industries.