The present work is devoted to nondestructive testing and to the investigation of the damping properties of lightweight sandwich panels using acoustic nondestructive testing methods. The objects of study are full-scale specimens of multilayer sandwich panels with fiberglass and carbon-fiber face sheets and a foamed polymer core. Artificial defects in the specimens included closed cavities, delaminations, and open cavities in the core. Using electrodynamic and impact shaker rigs, the damping properties of the multilayer panel specimen were determined under harmonic vibration excitation in the frequency range from 100 Hz to 10 kHz. Nondestructive testing of representative defects was performed by scanning laser Doppler vibrometry with noncontact acoustic stimulation provided by a gas-discharge electroacoustic transducer. The obtained results made it possible to evaluate the damping characteristics of composite sandwich panels, their ability to attenuate external acoustic excitation, and to detect defects in the frequency range from 100 Hz to 32 kHz.
This study investigates the acoustoelastic response of concrete elements subjected to flexural loading, with the objective of determining acoustoelastic coefficients for non-destructive stress estimation. While most existing research on the acoustoelastic effect in concrete focuses on uniaxial compression, this work extends the methodology to flexural conditions, where tensile and compressive stresses coexist within the same element. Ultrasonic pulse velocity (UPV) measurements were performed simultaneously in both tension and compression zones using dual ultrasonic pulse analyzers under controlled incremental flexural loading. Results revealed a clear stress-dependent variation in UPV under flexural conditions. In the compression region, velocity increased linearly with stress, indicating elastic stiffening consistent with acoustoelastic theory. In contrast, the tension zone exhibited a linear decrease in velocity due to microcrack initiation and tensile softening. Despite minor deviations caused by localized cracking, the overall velocity–stress relationship remained predominantly linear across different concrete mixes. On average, the compression zone showed a 2.5
The article describes the research of reference samples of the silumin group alloy included in the porosity scale kit, in order to determine the porosity score using X-ray computed tomography. Tomographic studies include two stages: determining the correspondence between the porosity indicated on the reference images and the porosity, determined by the grind, as specified in GOST (State Standard) 1583–93; unambiguous determination of porosity in a control object based on its tomogram.
To address the challenge of quantitatively characterizing early corrosion in metallic plates, this paper proposes a novel nonlinear ultrasonic method based on the zero-frequency component (ZFC) of low-frequency Lamb waves. By employing a low-frequency excitation strategy to suppress multi-mode interference, the proposed method achieves cumulative growth of the ZFC signal under the group velocity matching (GVM) condition, thereby significantly mitigating the influence of dispersion. Experimental investigations reveal that the nonlinear coefficient of the static component exhibits a distinct, non-monotonic “increase-then-decrease” evolution pattern with the aggravation of corrosion. Mechanism analysis indicates that this phenomenon is attributed to the competitive mechanism between the nonlinearity enhancement induced by incipient micro-defects and the coherent scattering attenuation caused by surface roughness in the later stages. This study validates the high sensitivity of the ZFC method to incipient damage, providing a solid theoretical foundation for the quantitative assessment of the entire corrosion process in metallic structures.
The paper presents data on the study of the effect of contrast photoperiods (12 and 16 hours) on the quality of cabbage crop seeds using the example of lines of doubled haploids of mapping populations of Brassica rapa L. grown under the conditions of phytopolygon of Agrophysical Research Institute. To study the quality of seeds, the method of microfocus radiography was used, in combination with visual and automatic decryption of X-rays and a conjugate assessment of seed qualities. For the first time, using the X-ray method, it was established that seed samples of 7 Brassica rapa L. genetic lines grown under conditions of a 16-hour photoperiod will have better inoculation qualities compared to those grown under conditions of a 12-hour photoperiod due to greater accomplishment, as well as lower values of the proportion of hidden defects evaluated visually from X-ray images: sign “d” (irregular darkening projections), sign “e” (noncompletion), sign “u” (angular projection), sign “p” (drawing), and sum of defects (d+e+u+p). It has been shown that with an increase in the total level of internal damage (voids, porosity), the total percentage of seed germination sharply decreases. The inverse correlation effect, confirmed by the correlation coefficients r_3 = - 0.877 by significance value ( p < 0.01 ) and r_6 = - 0.856 (p < 0.01) between the percentage of defective areas (X-ray) and germination indicators, proves the predictive value of X-ray signs for assessing seed sowing properties without destroying them.
Pulsed vibration excitation is a nondestructive technique that can assess the dynamic characteristics of materials (Young’s modulus, Poisson’s modulus) and the crack characteristics present in the specimen by measuring and analyzing the fundamental resonance frequency of an elastic hammer, and is constantly expanding in engineering practice. In this paper, a mathematical model is proposed to evaluate the crack characteristics present in various types of structural elements based on the excitation of pulsed vibrations with cracks. The relationship between the modal parameters and the crack characteristics is evaluated by applying the concept of modal strain energy. When a crack exists in a structure, the energy released varies with its size and location, which affects the natural vibration mode and natural vibration frequency of the structure. This effect was considered using the commercial software ABAQUS and experimentally verified using a high-temperature elastic modulus measurement device IET-1000 based on pulsed vibration excitation. The results show that the method suggested in this paper can fairly accurately identify the crack characteristics.
Flow maldistribution in packed columns plays a crucial role in reducing mass transfer efficiency in industrial process equipment in refineries and petrochemicals. In this study, gamma-ray scanning was used as a rapid, non-contact, and cost-effective technique to diagnose hydrodynamic problems in a live industrial HF alkylation rerun column. In this technique, a 137Cs source with 300 mCi activity and a NaI (Tl) detector were positioned on opposite sides of the column. The scanning was performed across the three radial paths (0°, –30°, 30°) within two packed sections, including Nutter Ring Type 1 (NR1) and Type 3 (NR3) packings. According to the results, there is a flow misdistribution and potential local blockage in the NR1 section, which is characterized by a systematic asymmetry of the count rate of 35
Implementing volumetric ultrasonic imaging based on the synthetic aperture focusing technique (SAFT) requires processing a large volume of ultrasonic signals and imposes high requirements on the ultrasonic transducers and multichannel ultrasonic electronics used. One promising approach to overcoming these challenges is to use non-uniform matrix phased arrays. Unlike conventional (uniform) matrix phased arrays, such probes enable a significant reduction in the number of active elements without a corresponding decrease in imaging quality. The layout of these probes is a key factor in determining their performance. Therefore, the array configuration must be chosen with respect to the ultrasonic imaging conditions. This paper proposes an algorithm for determining the optimal configuration of a non-uniform matrix phased array with active elements arranged in the form of a Fermat spiral. The algorithm is based on simulated annealing, which enables the effective solution of multi-parameter optimization problems. The developed algorithm was used to search for the optimal configuration under specific ultrasonic imaging conditions. Analysis showed that, under the considered inspection conditions, the obtained configuration has a point spread function that is narrow in the main lobe while having a low side lobe level. Furthermore, this non-uniform matrix phased array configuration reduces the number of elements by 9-fold compared to a uniform array, while maintaining the same aperture size. Experimental verification has confirmed that the proposed configuration provides high spatial resolution and a high signal-to-noise ratio in the restored acoustic images.
A non-destructive eddy current testing was adapted in this investigation to investigate the electrical conductivity of electrolytic tough pitch copper. Various joining methods were used to join the copper, which were gas tungsten arc welding with two modes (constant current and pulsed current), solder braze, phosphor bronze braze, and friction stir welding. The test result indicated that copper joints that were made using solid-state welding process, especially the friction stir welding, had a greater electrical conductivity (5.7 × 107 Sm/m), as compared to their counterparts. The given improvement of the properties can be explained by the existence of fine, recrystallized grains in the joint interface with no intermetallic layer observed in the area of the weld itself. Phosphor bronze brazed and solder brazed joints, in contrast, had low electrical conductivity because of the abundance of large number of discontinuities and creation of intermetallic layers.
The acoustic inspection method utilizing waveguide propagation effects (waveguide inspection or guided wave technique) with the use of torsional waves is finding increasingly widespread application in pipe inspection due to its ability to inspect long sections without scanning. Due to the dependence of the amplitude of the reflected torsion wave signals on a number of defect parameters, estimating their size is a difficult scientific and technical task. The paper presents an approach to determining the geometry of equivalent artificial reflectors. An analytical model is proposed, confirmed by finite element modeling and experimental studies using multi-frequency probing. The possibility of independently determining the length and depth of an equivalent artificial reflector based on the results of sounding a pipe at different frequencies is shown.
Electrical capacitance tomography (ECT) is a non-destructive imaging technique that uses capacitance values to reflect the distribution of the measured medium. The inherent “soft field” characteristic of ECT leads to a sensitive field distribution with higher sensitivity at the edges and lower sensitivity at the center, reducing the imaging resolution in the central region and presenting a major challenge to multi-object image reconstruction. To address the aforementioned issues, this paper proposes an ECT image reconstruction method based on a Gaussian kernel weighted sensitivity matrix. Four sensitivity matrices with different Gaussian kernel widths are presented, and their performance and quality of the reconstructed images are tested using sensitivity matrix and reconstructed image evaluation metrics. The results show that a sensitivity matrix based on an appropriately wide Gaussian kernel weighting can effectively improve its performance and enhance the quality of the reconstructed image.
Carbon fiber reinforced composites are susceptible to multiple types of damage during service in practical engineering applications, with complex interactions often occurring among different damage mechanisms. Reliable identification and characterization of these damage types are essential for ensuring the structural integrity and safe operation of composite components. In this study, acoustic emission (AE) techniques and deep learning methods are employed to classify damage modes in carbon fiber reinforced composites. A novel model, termed the efficient channel attention gated residual network (ECAG-ResNet), is developed by integrating gated convolutional layers and the efficient channel attention (ECA) mechanism into a residual network framework. The proposed model’s performance is systematically compared against five conventional baseline models. The raw acoustic emission signals are first processed using continuous wavelet transform (CWT), followed by data augmentation to enhance the model’s generalization capability during training. The wavelet-transformed and augmented data are then used as inputs to the neural network. The results indicate that the ECAG-ResNet model achieved a damage recognition accuracy of 93
In-service seamless rails are subjected to complex combinations of residual and operational stresses, and accurate assessment of their internal stress distribution is essential for maintaining track integrity and operational safety. This study introduces a noncontact nondestructive rail stress measurement approach that integrates electromagnetic acoustic transducers (EMATs) with surface-wave acoustoelastic theory. A novel EMAT with conformal meander-line coils integrated with an array of permanent magnets was designed to achieve consistent coupling with the rail head surface and efficient surface wave excitation. Key transducer parameters were optimized through simulation-based orthogonal experiments. A stress loading platform applied varying axial stresses to rail specimens; resulting changes in ultrasonic propagation time were observed to extract the acoustoelastic constant and establish a mapping between stress and time delay. Finally, an automated scanning system was utilised to measure full-length surface stress distributions on retired rail segment, revealing stress patterns closely associated with the rail’s service history and geometry. The proposed system achieved a measurement accuracy within 22 MPa and demonstrated high repeatability, indicating its potential as a reliable and efficient NDT method for stress evaluation of seamless rails.
A comparative analysis of contact and air-coupled approaches to acoustic excitation of a turbine blade was carried out using scanning laser Doppler vibrometry. The objective was to identify the natural frequencies and mode shapes of the blade. When contact excitation was applied using an electrodynamic shaker, modal analysis revealed eight vibration modes of the blade in the frequency range from 100 Hz to 9.5 kHz. Air-coupled acoustic excitation was implemented using a pulsed gas-discharge electroacoustic transducer operating based on a spark discharge in air at atmospheric pressure. It is shown that the gas-discharge electroacoustic transducer enables excitation of more than 30 vibration modes in the frequency range from 100 Hz to 38.5 kHz. When the air-coupled transducer was positioned 40 mm away from the blade, the vibration velocity amplitude on its surface reached 30 μm/s. Thus, the experiment confirms the feasibility of performing experimental modal analysis of a metallic part using air-coupled excitation and noncontact vibration measurement techniques.
While the integration of treated wastewater in cementitious composites offers a vital pathway for sustainable construction, its widespread adoption hinges on the reliability of standard quality control mechanisms. This study investigated the acoustic and mechanical invariance of standardized mortars produced with potable water (Mix 1), secondary-treated wastewater (Mix 2), and tertiary-treated wastewater (Mix 3). Rather than merely assessing material performance, this research validates the robustness of ultrasonic pulse velocity (UPV) as a nondestructive testing (NDT) tool that requires no specific recalibration for alternative water sources. Monitoring over a 90-day curing period revealed that the fundamental constitutive relationships between the wave velocity, density, and mechanical strength remained unaffected by the water quality. The experimental density adhered strictly to the reference models (R2 = 0.99), and a unified regression analysis demonstrated that a single predictive model accurately estimated the compressive strength (R2 = 0.96) and static modulus (R2 = 0.99) for all mixture types. The absence of statistically significant stratification between water sources (ANOVA, p > 0.97) confirms that the treated wastewater does not alter the micromechanical signal propagation characteristics. Consequently, this study establishes that existing standardized NDT frameworks are directly applicable to wastewater-based mortars, thereby removing a significant technical barrier to their industrial implementation.
High-strength pipes of class K60, which have anisotropic properties, are used for the construction of pipelines. When conducting ultrasonic inspection of welded joints using digital aperture focusing (DFA), it is usually assumed that sound propagates in a homogeneous isotropic medium. The DFA method can be modified to obtain images of reflectors in a homogeneous anisotropic medium, but for this one needs to know the type of symmetry and elasticity coefficients. Obtaining this information is an urgent problem. The article discusses two algorithms for estimating elasticity coefficients based on echo signals measured by one or two ultrasonic antenna arrays.
The article presents the results of the effect of plastic deformation by rolling on the microstructure, phase composition, mechanical and magnetic properties of multicomponent CoCrFeNiAl_0.8 and CoCrFeNiAl_1.0 alloys with different ratios of bcc and fcc phases. Microstructural analysis using EBSD showed that plastic deformation leads to an increase in the dislocation density, structure refinement, and the formation of predominantly deformed grains. An increase in the bcc phase content in the CoCrFeNiAl_1.0 alloy leads to a 20 CoCrFeNiAl_0.8 alloy. The strength properties of CoCrFeNiAl_0.8 samples increase by 7
Many welded joints that are inspected using ultrasonic waves have inhomogeneous anisotropic properties. The digital aperture focusing (DAF) method can reconstruct high-quality images of reflectors in such welded joints, but for this it is necessary to know the distribution of crystallite rotation angles and the elasticity coefficient tensor in the region of deposited metal. To describe the inhomogeneous anisotropic properties of the deposited metal region, it can be divided into several homogeneous anisotropic regions differing from each other only by the crystallite rotation angle. The second option involves using the MINA model, which analytically describes the crystallite rotation angles as a function of coordinates. By comparing the signals reflected from the bottom of the sample measured by two or one antenna array with the bottom signals calculated in the Kirchhoff approximation, it is possible to estimate the crystallite rotation angles and the elasticity coefficients of the deposited metal region for a given type of symmetry. When working with the MINA model, its parameters and elasticity coefficients can be estimated. The effectiveness of the proposed approach has been demonstrated in numerical and model experiments.
Acoustic source localization plays a vital role in fault diagnosis, and time difference of arrival (TDoA) is an important acoustic source localization method. In engineering practice, non-stationary working conditions and strong noise background bring challenges to TDoA and fault identification. In this paper, a novel acoustic source localization method called ultra-narrow band modal decomposition (UNBMD) based TDoA is proposed. First, frequency-domain windows corresponding to characteristic modes is constructed to enhance the decomposition accuracy of signal under strong noise. Second, correlation analysis is utilized to obtain accurate time delays for each channel. In the simulation studies, signal-to-noise ratio (SNR) and waveform similarity are adopted as evaluation metrics. Comparative analysis with variational mode decomposition and band-pass filtering methods demonstrates that the proposed approach achieves a waveform similarity of 99.86
In the structural health monitoring of pipelines, the accurate localization of acoustic emission (AE) signals generated by crack propagation is critical for leakage prevention. The accuracy of the traditional time difference of arrival (TDoA) localization method drops sharply due to waveform distortion, which severely restricts the engineering application of acoustic emission technology. To address this challenge, this paper proposes an interpretable artificial intelligence localization method validated against physical principles. This method employs an XGBoost model optimized via Bayesian optimization (BO), which avoids reliance on constant wave velocity by learning multi-dimensional acoustic features. Experimental results demonstrate that the proposed model significantly outperforms the traditional TDoA method, reducing the mean absolute error (MAE) and root mean square error (RMSE) by 71.7 and 77.4
