Russian Journal of Nondestructive Testing最新文献

This article continues and supplements the article with the same title published in Russian Journal of Nondestructive Testing, no. 1, 2022, which provides six ways to assess the quality and reliability of semiconductor products (SCPs) using low-frequency (LF) noise parameters. This paper presents a generalization of the results previously obtained by the authors and describes four more methods for diagnosing and evaluating the reliability of SCPs by varying the parameters of low- frequency noise under additional external influences such as electrostatic discharge and (or) thermal annealing. It is shown that additional impacts make it possible to increase the reliability of the assessment of the SCP reliability.

The structural, microstructural, optical, and elastic properties of polycrystalline perovskite series, Ca_1+xCu_3–xTi₄O₁₂; x = 0–1.0, have been investigated employing X-ray powder diffractometry, scanning electron microscopy, UV–Vis spectroscopy, and ultrasonic pulse-echo selection technique at 300 K. The primary structural parameter and ultrasonic parameters; longitudinal wave velocity (V₁), the amplitude of transmitted and reflected pulses a_o/a_n were used to calculate porous values of various elastic parameters such as shear wave velocities V_s, mean sound velocity V_m, elastic moduli L, B, G, E, Debye temperature θ, Poisson’s ratio σ, acoustic impedance Z, internal friction Q^–1, absorptivity A, adiabatic compressibility B_a, Lame’s constant λ_L, and Vickers micro-hardness H_v. The elastic constants were emended to a void-free state using eight distinct semi-empirical methods. These models are principally relying on the pore morphology in the material. Depending upon the correction model employed, L_o is found to decrease from ~21.5 to ~39.5%, B_o from ~17.4 to 45.6%, while E_o and G_o are found to decrease from ~22 to 34% on Ca²⁺ substitution (x = 0–0.5) in the system. Besides, the observed increase in different elastic moduli for x = 1.0 composition is found to vary from 0.3 to 7%. The compositional dependency of elastic moduli has been explained in terms of the change in interatomic bonding strength produced by variations in interatomic distances, microstructure, and electronic configuration. The values of Pough’s ratio B_o/G_o, Frantsevich’s ratio G_o/B_o, and Poisson’s ratio σ_o suggest the brittle nature of prepared ceramics.

Creating fast parallel iterative statistical algorithms based on the use of graphics accelerators is an important and urgent task of great scientific and practical importance. An algorithm based on the method of maximizing the maximum likelihood expectation (maximum likelihood expectation maximization—MLEM) is considered. The MLEM is a numerical method for determining maximum likelihood estimates and, since its first application in the field of image reconstruction in 1982, remains one of the most popular statistical image reconstruction methods and is the foundation for many other approaches. A new version of the MLEM parallel algorithm is proposed that provides global convergence of the iterative algorithm. To parallelize the algorithm, we use the texture mapping method using the OpenGL graphics library. The parallel algorithm is described in as much detail as possible. Examples of several reconstructions of images of aluminum casting products are given. The obtained result can be used for nondestructive testing of various industrial products, including testing of foundry products.

The set of operations on diagnosing the changes in the properties of materials due to aging includes accelerated climate tests (ACTs) and pre- and post-ACT performance tests. Along with the use of various methods for diagnosing defects that arise and develop during aging, it is also important to determine changes in the thermophysical, hydrophysical, and other properties of materials subject to long-term operation that are associated with changes in the material structure. In this paper, we present a method for synchronous calculation of changes in thermophysical and hydrophysical properties of materials due to material aging and respective changes to the hygrothermal modes of products under long-term storage and operation. An experimental setup and a method for experimental-analytical determination of the thermophysical properties of materials at variable heating rates, as well as a method of synchronous calculation, are presented. The experimental-analytical determination method was developed using the results of thermal testing of specimens both subjected to ACT and without ACT. The analysis of the test results makes use of the approximation-superposition method to solve the inverse heat conduction problem.

This study investigates the enhancement of Euphorbia Tortilis Cactus (ETC) infused concrete, focusing on its microstructural characteristics and mechanical properties. ETC concrete, known for superior tensile ductility and durability, was characterized using advanced 3D X-ray tomography and energy dispersive X-ray spectroscopy (EDX) analysis. Specimens with a 9% ETC extract mix underwent high-resolution Micro Computed Tomography scanning, revealing an average porosity of 3.3% and providing detailed insights into internal features like pores, fibers, and aggregates. EDX mapping identified key elements, including Si, O, Mg, and Ca, highlighting calcium carbonate and brucite formations. This research addresses gaps in understanding ETC concrete’s microstructure and mechanical behavior, using non-destructive imaging and chemical analysis to offer comprehensive insights. The findings suggest that ETC concrete can be optimized for enhanced performance in sustainable construction, highlighting its potential for applications requiring high durability and ductility. The study’s novelty lies in its application of advanced imaging and analysis techniques to optimize ETC concrete mix designs, assess durability, and develop strategies for mitigating structural issues, thus providing valuable insights into the material’s properties and behavior.

The widespread introduction of antenna arrays into the practice of ultrasonic testing has made it possible to obtain images of reflectors using either phased array technology or digital focusing of aperture (DFA) technology. However, many current regulatory documents governing the rules for conducting ultrasonic nondestructive testing in nuclear power engineering, petrochemistry, gas production industry, etc. require determining the equivalent dimensions of reflectors. The present article proposes a method for calculating the DAF-DGS array to determine the diameter of an equivalent flat-bottomed hole (FBH) when analyzing an image. It is shown that it is more efficient to work not with the amplitude of the image, but with the integral amplitude. Numerical experiments have shown the accuracy of the order of ( pm 0.1) mm in determining the FBH diameter. In model experiments, the accuracy of determining the FBH diameter was better than 0.2 mm in absolute value.

Poisson white noise is a typical non-Gaussian noise that can induce stochastic resonance to detect feature signals submerged within it. In this paper, we propose a detection method for overdamped tri-stable stochastic resonance in Poisson white noise environment. Based on the model of over-damped tri-stable stochastic resonance. To begin with, the influence of the parameters of the tri-stable system on the potential function is studied. Then, the cross-correlation coefficient C_sx is used to measure Poisson white noise under different pulse arrival rates β, system structural parameters a, b, c, and noise intensity D the law of action on system resonance. Ultimately, the system is successfully applied to the fault diagnosis of bearing under variable speed conditions and the background of Poisson white noise, and the simulation and experimental results are compared with the classical bistable system. The findings suggest that the performance of the system significantly surpasses that of the classical bistable system.

The problem of random oscillations generated by an internal defect within the neighborhood of the boundary of an elastic massive body at the prefailure stage is considered. The study is based on the results of the invariant method in the theory of acoustic emission (AE), according to which the statistical distribution of the values of the parameters of acoustic emission (AE) signals due to a defect obeys the stability condition when the body remains at the same prefailure stage. A mathematical model of a nonstationary wave field of displacements in an elastic massive body is constructed and the issues of the correctness of its application are studied. The problem is reduced to the study of a certain boundary integral equation in special classes of stochastic processes. We pose the problem of reconstructing and describing the nature of the random process of defect emission on the free boundary of the body based on AE signals. The data of numerical analysis are presented.

Ti–6Al–4V alloy is used in high-temperature aerospace applications such as aircraft turbine discs, airframes, and other structural parts. Solid particle erosion is quite common in aerospace components. In the present work, a study has been conducted to see the effect of solid particle erosion on Ti–6Al–4V alloy fabricated by direct metal laser sintering. The fabricated sample was characterized using optical microscopy and scanning electron microscopy. It was observed that a long martensitic phase structure (in the form of α/α' laths) was retained since the heat treatment temperature was far below the β transus value. Using the Taguchi experimental approach, the SPE tests were conducted for different impact angles, velocities, and temperatures. This approach optimized the number of experiments for measuring the erosion rate and predicted the most influencing variable in the test. The scanning electron microscopy technique was also used to characterize the eroded sample. The effect of impact velocity dominated the erosion behaviour of Ti–6Al–4V alloy, followed by temperature and impact angle. At highest temperature of 650 K, erosion rate decreased with an increase in impact angle and increased with an increase in impact velocity. This study aims to identify the optimal parameter combination to minimize the erosion rate.

A mathematical model of radiation transparencies in the computational implementation of the dual energy method based on analog discrimination of the initial signals is presented. The generalized mathematical model of radiation transparencies in the analyzed implementation of the dual energy method is based on an analog separation of initial electrical signals from an X-ray detector by amplitude into low- and high-energy signals with subsequent counting of these signals. The analog separation of X-ray detector output signals by amplitude is carried out using a two-channel amplitude analyzer. The proposed model takes into account the maximum energy of X-ray photons, the energy threshold for dividing signals into low- and high-energy ones, materials and sizes of radiation-sensitive detector elements, and parameters of test objects. The model can be used to conduct research on the effect of noise caused by the quantum nature of X-ray radiation on the quality of identification of attenuating material, for example, by effective atomic number, in relation to the considered implementation of the dual energy method, as well as for the reasonable choice of parameters of the corresponding dual energy systems of digital radiography and X-ray computed tomography.