Russian Journal of Nondestructive Testing最新文献

The utilization of reinforced concrete structures has an extensive past within the realm of infrastructure due to its economical nature, impressive robustness, ability to withstand adversity, and eco-friendliness, alongside the uncomplicated procurement of essential raw materials. Nevertheless, these structures have certain drawbacks, including limited tensile strength and malleability, resulting in cracks within the edifices. These cracks have the potential to permit the ingress of chlorides, leading to corrosion of the reinforcement. In order to effectively address issues of quality control, upkeep, and strategic renovation of these buildings, it becomes imperative to employ a suitable nondestructive testing and assessment technique for comprehensive surveillance aimed at early detection of hidden rebar corrosion. Infrared thermal wave imaging has arisen as a feasible method for the nondestructive examination and assessment of reinforced concrete structures. This is attributed to its ability to perform comprehensive, remote, and rapid inspections, facilitating the monitoring of subsurface rebar corrosion. The current section introduces an innovative approach known as Digitised frequency modulated thermal wave imaging (DFMTWI) within diverse thermal nondestructive testing methodologies. This technique is put forward to numerically test and evaluate rebar corrosion within concrete structures, and the obtained results are then compared with the frequency-modulated thermal wave imaging (FMTWI) results by taking signal-to-noise ratio (SNR) as a figure of merit.

This paper presents an innovative approach to improve the accuracy and resolution of defect detection in glass fiber-reinforced plastic (GFRP) composites using pulse compression analysis for thermal wave imaging. GFRP materials, widely utilized in various industries owing to lightweight and durable properties, often present challenges in identifying subsurface defects. Traditional thermal wave imaging techniques face limitations in achieving high-resolution results. The study outlines the theoretical foundation of pulse compression and its application in thermal wave inspection. A comprehensive experimental setup was designed to validate the effectiveness of the proposed methodology. Results indicate a significant improvement in the localization and characterization of defects within GFRP composites. The findings of this research hold implications for nondestructive testing and quality control in industries relying on GFRP materials. The integration of pulse compression analysis into thermal wave imaging establishes a promising avenue for precise defect detection, contributing to the reliability and integrity of GFRP composite structures. Also, two key metrics, absolute thermal contrast and signal-to-background contrast, are used for quantitative analysis.

Fe–Cr alloys are widely used in power, petroleum, and manufacturing industries for their good resistance to corrosion and oxidation at high temperatures. Ultrasound is the only nondestructive method so far to measure the residual stress of in-service components. However, for parts with material anisotropy, such as materials processed by rolling, the measurement accuracy is highly restrained. In this paper, a rolled 316L stainless steel sample is used to study the influence of texture on the measurement of residual stress by ultrasonic surface wave. The experimental results show that the propagation velocity of surface waves in the sample has anisotropic characteristics. The wave velocity parallel to the rolling direction (0°) is the maximum, and the wave velocity perpendicular to the rolling direction (90°) is the minimum, thereby affecting the measurement accuracy. It is found that reducing the frequency of surface waves can reduce the influence of anisotropy. Therefore, a low-frequency method and modified formula are used to improve the measurement accuracy. The maximum error in the rolling direction is reduced from 21.3 to 3.6 MPa, and the maximum relative error is also reduced from 45.4 to 9.0%. The modified formula can further reduce the influence of anisotropy, with the maximum error value further reduced to 2.3 MPa, the maximum relative error reduced to 4.9%, and the surface wave detection accuracy effectively improved.

Nanotubes with multi-walled structures have the ability of changing the characterization of poly (Silicone Rubber) nanocomposites. In this way, silicone rubber/multiwalled carbon nanotubes (SR/MWCNTs) nanocomposite is achieved by reaction with multifunctional. A new design of SR/MWCNT nanocomposites was developed as a result of experiments to clarify the advantages of filling the MWCNTs with different patterns within the dielectrics. As part of this work, silicone rubber/multiwalled carbon nanotube nanocomposites and room temperature vulcanization (RTV) methods were used to fabricate piezoelectric sensors. The analysis of the frequency response of SR/MWCNT nanocomposites has been conducted under variable thermal conditions (20–40°C). This study succeeded in applying poly (Silicon Rubber) nanocomposites as piezoelectric sensors by exhibiting new electrical characteristics (resistance, capacitance, real and imaginary impedance) under various thermal conditions based on certain types and concentrations of MWCNTs.

In the introduction to the article we mention four factors that are most important for ensuring the accuracy of characterizing defects during ultrasonic inspection, viz., parameters of artificial reflectors in samples, compliance of the acoustic properties of the material of tuning samples and tested products, transient characteristics of electroacoustic paths, and methodological features of measurements. The present article is devoted to the analysis of the first and partly fourth of listed factors. The review of reflectors, the use of which is regulated in various standards, is carried out. Advantages and disadvantages of flat-bottomed holes, segmental and corner reflectors (“notches”), lateral (SDH) and vertical cylindrical holes, and grooves are noted. Taking into account the specific features of ultrasonic wave scattering, it is noted that artificial “reflectors” such as “grooves” and SDHs are used to adjust the parameters of modern diffraction testing methods. It is recommended to expand the use of grooves, SDHs, and vertical drilling when revising the standards governing the use of conventional echo methods. The estimation of accuracy of measurement of defects parameters, first of all, the crack tip coordinates, with application of modern digital methods of information processing during ultrasonic testing is given. It is indicated that to increase the measurement accuracy and to determine the position and orientation of cracks in welds, it is necessary to create a database of digital twins of samples with artificial reflectors and products with real defects. A general scheme of executing the quality control is given that takes into account the use of standards (measures), digital models of artificial reflectors, and digital twins of the testing process to ensure the necessary detectability of defects and reliability of manual, automated, and, potentially, automatic testing.

In this paper, a characterization study of concrete samples with ultrasonic surface waves at hundreds of kilohertz frequency range is presented. These waves are generated and received by using 0.5 MHz-nominal frequency transducers. This investigation therefore concerns the first centimeters in the nearby of the material surface. The study was applied to concrete specimens for which a compositional parameter which is the water-to-cement ratio (W/C) has been varied. The latter affects the density and porosity of the material and therefore its mechanical properties. In addition, the evolution of acoustic and mechanical parameters of the concrete during its curing period has been investigated. The acoustic velocity and attenuation parameters are determined by exploiting the time of flight and the amplitude of the received ultrasonic signals. This study shows that the variation of the water-to-cement ratio affects the velocity of propagation of the surface waves and also leads to a variation of the mechanical strength of the concrete. It concludes that there is a strong correlation between the strength of the concrete, the ultrasonic velocity, and the W/C ratio. The results obtained by the destructive evaluation, which provides a measurement of the compressive strength by mechanical crushing test, confirm those obtained by the non-destructive evaluation of concrete. The study shows that this type of non-destructive testing using ultrasonic surface waves is beneficial particularly when the concrete structure is only accessible from the surface or when the propagation of the bulk waves is perturbed by the presence of reinforcements.

A mathematical model of defects of the inner surface of a ferromagnetic plate is presented. The model compares crack-type defects with wide-opening corrosion defects.

We present the results of studying the influence of the geometric shape of the damper on its effectiveness and the overall efficiency of the emission–reception system. One of possible shapes for the damper is considered where it is a truncated cone with the generatrix tilted relative to the piezoelectric plate plane. A criterion for evaluating the efficiency of the damper operation is proposed. The study includes the results of computational-theoretical (using the finite element method) and experimental research on the influence of the tilt angle of the damper generatrix on the signal reflected from its rear part. The generatrix tilt angle at which the minimum of noise signal is achieved is determined. A study of the emission–reception system under load on the aquatic environment is carried out. A satisfactory agreement between the theoretical and experimental results is noted.

An ultrasonic nondestructive evaluation technique is proposed for ultrasonically welded joints of multi-strand copper cables in automobile wire harness terminals. The 32/128 ultrasonic phased array system is used to acquire the complete matrix data of the pulse-echo of the wire harness joints. The eigenvalues of the time, frequency, and time-frequency domains are extracted, and the wire harness joint quality is classified by machine learning. Firstly, 28 wire harness terminal joint samples were prepared 14 under different welding parameters; 14 were okay (OK), and were negative (NG). Then a linear array probe 5L32-0.6 × 10 is used to collect and preprocess the complete matrix data in these joints, and 11 200 echo signals are obtained. A principal component analysis algorithm was employed for data dimensionality reduction and denoising. Finally, machine learning algorithms were used to train and verify the model. The accuracy and performance of the traditional algorithms such as Logistic Regression (LR), K-Nearest Neighbor (KNN), Decision Tree (DT), Naive Bayes (NB), Support Vector Machine (SVM), and Neural Network (NN) were compared. The KNN and NN perform well in this study. In the test set, the accuracy of KNN and NN reached 90%. The study showed that echo features could effectively identify joint quality.

As a result of measurements carried out using the standing waves method, hidden defects were detected inside the prosthetic feet details made of composite material. When comparing the obtained amplitude-frequency spectra of intact samples and samples with defects based on the first peaks corresponding to the first bending wave modes, it was revealed that the values of the resonant frequencies of defective samples were lower relative to the frequency values of the spectra of the intact ones. That observation indicated that the material of defective products might have reduced strength characteristics. Also, when studying some samples, the presence of additional peaks was noted, which indicated the appearance of new reflection boundaries corresponding to the appearance of defects in the test samples. The maps of amplitude distributions in the studied samples were obtained. A preliminary comparison was made with the results of examining samples using the OmniScan X3 device manufactured by OLYMPUS company. The results obtained indicated the presence of an increased number of reflection boundaries, as well as an increased bulges content, which probably arise during the process of products gluing. The analysis confirms the possibility of successfully using the standing waves method as a method for detecting hidden defects in composite material.