Russian Journal of Nondestructive Testing最新文献

A generalization of the analytical expression for the Rayleigh wave velocity in algebraic form and formulas with trigonometric and hyperbolic functions that do not contain cubic radicals are obtained. Their application is considered using the example of calculating the derivative of the Rayleigh determinant in problems of excitation and diffraction of surface acoustic waves in a homogeneous isotropic elastic half-space, allowing solutions for strain and stress fields in quadratures. The results obtained can help in obtaining analytical expressions, as well as approximate formulas, and reduce the calculation time at the stage of numerically solving problems of diffraction and excitation of acoustic waves. Approximate formulas proposed by L. Bergmann, E.G. Nesvijski, P.C. Vinh, and P.G. Malischewsky are also considered and their more optimal variants are proposed. The results obtained can help in obtaining and analyzing analytical expressions, reduce the calculation time at the stage of numerical modeling of the problem of excitation and propagation of acoustic waves, and substantially reduce the measurement error in flaw detection and nondestructive material quality control.

Cracks, spalling, cavities and other damages occur in the process of long-term service of concrete, so that the bearing capacity of the building decreases, which needs to be reinforced by the adhesive steel plate reinforcement method. However, debonding phenomenon can occur at the interface between steel plate and concrete, which affects the overall stiffness and load carrying capacity of the structure, so debonding detection at the steel-concrete interface is particularly important. In this paper, a reference-free Lamb wave-based identification detection method for steel plate-concrete debonding is proposed, in which the Hilbert energy spectrum is used as a damage factor. The method does not require a preset reference signal, which is obtained by comparing the debonding signals. Firstly, the simulation is carried out by finite element software, the circular sensor array is arranged on the surface of the steel plate, and each sensor acts as excitation and reception, the Hilbert energy spectrum of the signal is obtained, the damage coefficient is calculated, the probabilistic imaging algorithm is utilized to realize the localization of the debonding position and the imaging, and finally the simulation is verified by experiments. The results show the feasibility of the method in debonding identification detection.

The results of cyclic tests of  08Kh18N10T structural steel are presented. The tests were carried out using the accelerated Locati method. The experimental data obtained showed that cyclic deformation of austenitic steel leads to the formation of deformation martensite, as indicated by the results of X-ray phase examination of the sample. The study of the microstructure of steel also indicates structural and phase transformations occurring in steel. The eddy current signal was measured on the test sample before and after the tests. Changes in the phase and amplitude of the eddy current signal occurring after the tests indicate the possibility of using this method to determine the formation of deformation martensite in austenitic steel.

As a critical means of energy transportation, oil and gas pipelines transport essential resources like oil and natural gas. However, as the service life of these pipelines increases, they encounter various adverse factors that gradually compromise their structural integrity, making them prone to defects. These defects may lead to serious safety incidents, posing threats to human lives, property, and the ecological environment. Traditional defect recognition methods often fall short in accuracy and reliability due to the complexity of the pipeline operating environment. This paper proposes a novel damage recognition method for oil and gas pipelines that combines multiscale adaptive convolution (MSDAC) with a long short-term memory network (LSTM). The MSDAC module integrates a multiscale convolution network with a channel attention mechanism, enabling it to extract multiscale defect features from the original acoustic signals and dynamically adjust feature weights at different scales to enhance key feature responses. The output from the MSDAC module forms a new multiscale feature vector, which serves as input for the LSTM to capture contextual features with temporal dependencies, improving defect identification performance. The proposed method is validated using acoustic signals from actual pipeline defects. Experimental results demonstrate that its accuracy, precision, recall, and F1-score exceed 95% for identifying defects such as No defect, Crack, Delamination, Pit, and Perforation. The method outperforms traditional models, showcasing excellent noise resistance and generalization ability across varying conditions, thus confirming its efficacy in oil and gas pipeline defect recognition and classification.

Double-exposure laser speckle photography is an extensively used technique for measuring in-plane displacements in experimental mechanics. Double-exposure specklegrams recorded using this technique give speckle correlation fringes of Young’s type in a diffraction halo when illuminated with an unexpanded beam of laser light. In-plane displacement is measured by measuring the width of these fringes. However, due to diffraction halo intensity, the minima of speckle correlation fringes move away from the center, and the maxima come closer to the center. This decreases the accuracy of the measurement of fringe width and leads to errors in the in-plane displacement measurement. To get rid of the effect of diffraction halo on the measurement of widths of speckle correlation fringes, several researchers have done considerable work for the necessary corrections in the measured value of fringe widths. Further, the double-exposure specklegrams record the vector displacement of a point, and the corresponding Young’s fringes are always orthogonal to the in-plane displacement. Thus, to measure the in-plane displacement components accurately, one has to accurately measure the orientation θ of these fringes with x and y directions. Any inaccuracies in measuring θ may lead to significant errors in the measurement of in-plane displacement components. To eliminate these errors in the measurement of width of speckle correlation fringes, we present an experimental technique for the measurement of the in-plane displacement component in speckle photography, where we have used two identical holographic lenses with dual apertures and data regarding the fringe spacing have been obtained from ± first diffracted orders. Experiments have been performed using suitably designed holographic lenses. In-plane displacements given to a diffuse object have been measured using the experimental method proposed in this work. The obtained results are in good agreement with the results reported with the necessary corrections in fringe width in the literature. This confirms the validity of the proposed method.

Infrared thermal wave imaging, a pivotal technology in active infrared thermography, has found widespread application in the characterization of defects. However, the transverse thermal diffusion phenomenon leads to significant attenuation of the heat wave signal, severely restricting the sensitivity of this technique in detecting minute defects. This paper introduces an advanced method for compensating transverse thermal diffusion, referred to as the WI-ITHFS approach. The method utilizes wavelet decomposition to extract high-frequency details from the optical flow field, thereby capturing more precise information regarding heat flow dynamics. Subsequently, the gradients of these high-frequency coefficients are computed, and the coefficients of the adaptive smoothing term in optical flow estimation are dynamically adjusted via an enhanced Sigmoid mapping function, with the aim of improving the accuracy of the estimation. A feedback iteration strategy is also incorporated to further enhance both the stability and precision of the optical flow estimation. The performance of the proposed method is evaluated against the traditional Horn–Schunck optical flow method in terms of deformation error, energy values, and gradient consistency, with results demonstrating the superiority of the proposed approach. Finally, the heat flow compensation model is optimized using accurate optical flow estimation, integrated with a fusion strategy combining nonlocal steering kernels and background subtraction techniques. The experimental results demonstrate that the WI-ITHFS method significantly outperforms existing methods, especially in the detection of minute defects within the subsurface of aluminum alloy thin plates, offering a notably higher signal-to-noise ratio (SNR) in terms of contrast enhancement and defect detection accuracy.

This study develops an optimized coil-only electromagnetic acoustic transducer (EMAT) system with enhanced detection circuitry for stainless steel 304 NDT applications. The proposed design specifically addresses ultrasonic echo attenuation (≤0.8 mVpp) and substandard signal-to-noise ratio (SNR < 15 dB) through key improvements A finite element model integrating field-circuit coupling was developed to simulate the coil-only EMAT detection process. Simulation analysis and experimental validation were conducted to evaluate the effects of coil wire diameter and outer diameter on excitation and reception efficiency. Subsequently, Testing experiments were conducted on  stainless steel 304 to investigate the relationships between discharge current and echo characteristics, high-voltage charging capacitance and voltage, and low-voltage charging capacitance and voltage. The results demonstrated that the optimal configuration involved a spiral coil with a wire diameter of 0.25 mm and an outer diameter of 20 mm. The recommended parameter values for high voltage, low voltage, high-voltage capacitance, and low-voltage capacitance were 800 V, 180 V, 300 nF, and 1000 μF, respectively.

The possibility of implementing the high-dose dosimetry method based on a combination of electron paramagnetic resonance (EPR) and thermally stimulated luminescence (TL) phenomena was investigated. Domestically produced polytetrafluoroethylene (PTFE) was used as an ionizing radiation detector. Detector samples were irradiated with accelerated electrons with an energy of 10 MeV with doses from 10 to 50 kGy. After irradiation, the intensities of the EPR and TL signals were measured from each detector. The dependence of the EPR signal intensity on the radiation dose was linear. The TL parameters were equal to: maximum temperature ({{T}_{{text{m}}}} = 164~^circ {text{C}}), form factor ({{mu }_{g}} = 0.45), frequency factor (S = 4.44 times {{10}^{{11}}};{{{text{s}}}^{{ - 1}}}), activation energy (E = 1.14) eV. The spectral composition of TL had a wide band with a luminescence maximum of approximately 425 nm. The dose dependence of the TL output was also linear in the studied dose range. Annealing of EPR and TL signals occurred in the same temperature range, 160–240°C. The correlation of dose dependences of normalized intensities of EPR and TL signals, the similarity of their temperature ranges of annealing intensities, indicated that the EPR and TL properties of PTFE detectors are associated with changes in the charge states of the same centers.

The article presents the results of tests of the aircraft landing gear support spring made of Toray T800 prepreg and 30 KhGSA steel. The cases of its testing by acoustic emission, ultrasonic methods and strain gauging during the simulation of horizontal aircraft landing and during the simulation of landing with a side impact are considered. During the spring tests, strain gauge was used, and tensile, compressive and torsional deformations were studied. The changes in the main informative parameters of acoustic emission signals (MARSE energy parameter, median frequency, structural and two-interval coefficients) were analyzed. The defect type was determined using a modified structural coefficient. This made it possible to increase the speed of information processing, since its decrease corresponded to the matrix destruction, and its increase corresponded to the fiber destruction. The location of acoustic emission signal sources corresponding to the structure area with the greatest relative deformations was obtained. It was noted that when simulating a horizontal landing of an aircraft, after removing the load, residual deformations were observed in the spring material.

EPR—a high-dose dosimetry method for use in monitoring radiation technologies has been tested for a proton beam with an energy of 18 MeV using a domestic brand of polytetrafluoroethylene as a radiation detector and an original EPR spectrometer. It has been shown that the dose range of the EPR signal is limited to 1.5 MGy, after which saturation occurs. Doses exceeding this value can be measured using additional signals in the EPR spectrum. It was found that irradiation of the detectors makes them gamma radioactive. The energy of the gamma radiation and the half-life of the source corresponded to the isotope ¹⁸F obtained in the nuclear reaction ¹⁸O(p,n)¹⁸F, which indicated the presence of oxygen in the material of detectors, which determines their paramagnetic properties.