Russian Journal of Nondestructive Testing最新文献

The effect of fatigue failure on the elastic characteristics of metastable austenitic steel AISI 321, Poisson’s ratio and acoustic anisotropy parameter, was studied. The elastic characteristics were calculated based on the data of ultrasonic measurements of the propagation time of longitudinal and shear elastic waves. The volume fraction of the strain-induced martensite was determined by the eddy current method. Theoretical studies have shown that the main factors influencing Poisson’s ratio are the accumulation of microdamage and changes in the phase composition. The change in the acoustic anisotropy parameter is associated with the effect of cyclic deformation on the crystallographic texture of the material matrix and the formation of oriented crystals of strain-induced martensite. Based on the analysis of experimental results, expressions have been obtained for calculating damage and relative accumulated plastic strain according to acoustic measurements, which are widely used in engineering practice to determine the fatigue life of structural materials.

Fatigue damage severely impairs high-strength marine steel performance, threatening the safety of ships and offshore engineering structures. Due to the abrupt nature of structural fatigue failures, early detection of fatigue microcracks is crucial for ensuring structural reliability. The detection of fatigue damage was experimentally and numerically investigated in AH36 marine steel using nonlinear ultrasonic technique. According to the distribution features of fatigue damage in marine steel, a three-dimensional finite element model is proposed to investigate the nonlinear ultrasonic method for the detection of randomly distributed fatigue microcracks. The microcrack distribution is much closer to the actual state of fatigue microcracks in metal than that of previous studies which used two-dimensional plane strain models with the individual crack or distributed cracks. The high-harmonic was induced by the contact behavior of crack surfaces. The results revealed that the relative nonlinear coefficient increases with higher microcrack number and length, but decreases with larger microcrack width. Additionally, the FE model, which closely approximates the actual distribution of fatigue microcracks in metallic materials, provides a new research avenue for a more comprehensive understanding the nonlinear interaction between ultrasonic waves and fatigue microcracks.

This study introduces an innovative approach for inspecting composite structures using advanced nondestructive testing (NDT) techniques, specifically ultrasonic inspection utilizing the UPK-T36 ULTRAPAC II immersion system. The primary objective is the analysis of glass/epoxy plate samples subjected to varying levels of impact energy. A comprehensive exploration, encompassing A-scan, B-scan, and C-scan mappings, has been undertaken to discern and characterize defects, with an explicit focus on the intricacies of delamination. The root mean square (RMS) was employed to statistically assess the structure’s condition in this study. The underpinnings of ultrasonic NDT, delving into the intricacies of wave propagation modeling, probabilistic defect detection, three-dimensional localization, and multi-scale characterization, have been examined with precision. The results collected through the utilization of the ULTRAPAC II UPK-T36 immersion system for defect reconstruction across a diverse array of samples unequivocally affirm the efficacy of the proposed method, producing outcomes of satisfaction.

In this study, the elastic properties of porous cylinders are evaluated using a nondestructive method based on ultrasonic wave propagation. In the scientific community, the elastic properties of materials play a crucial role. Measuring these properties can reveal valuable details about the mechanical properties of these materials. The scattering of a plane acoustic wave has received a great deal of attention from researchers due to its growing interest in many disciplines. Many authors have studied the acoustic scattering by means of cylindrical components (e.g. tubes, cylinders, etc.). This study shows how to analyze the distribution of circumferential waves with increasing porosity using the modal view of the waves propagating around the circumference of a cortical bone. This technique is applied on a signal backscattered by an porous tube of radius ratio b/a = 0.7 (a is the external radius and b is the internal radius). Our investigation revealed a correlation between bone porosity, fluid saturation, and pore radius, and changes in elastic properties. The Schoch model was developed to investigate the propagation of ultrasonic waves in porous bone. The results demonstrate the effectiveness of this approach for acoustic characterization and describing the impact of osteoporosis on bone elasticity.

The meso-damage process of Q355E steel metal used in wind power tower is accompanied by the release of transient stress wave. The information of stress wave can be collected by acoustic emission detection technology. However, due to the lack of intuitive and visual means, it is difficult to quantitatively evaluate the meso-damage of metal materials by acoustic emission information. In this paper, Deben Microtest 2kN in situ tensile test bench, FEI Quanta 450 field emission scanning electron microscope and SAEU2S acoustic emission acquisition system are combined to build a dynamic observation experimental system of acoustic emission source. The results show that there is a good correspondence between the in situ tensile displacement-load curve and the amplitude history of the acoustic emission signal. At different stages of in situ stretching, the acoustic emission signal has characteristic signals. The changes of the microstructure of the samples were observed, and the characteristic acoustic emission signals during the stretching process were analyzed by parameter analysis and waveform analysis.

The nuclear thickness gauging systems play an important role in the industry for invasive, online, and continuous measurements. The goal of the Beta thickness gauge is to obtain a precise measurement of thin films in which the performance of these gauging systems and output data quality are evaluated with the parameters including resolution, contrast, etc. The choice of the emitted suitable energy distribution of the Beta source is one of the effective factors in the system performance and precise measurement of thin films. In this research, a Beta thickness gauge with ¹⁴⁷Pm and ⁸⁵Kr sources was simulated and evaluated in biaxially oriented polypropylene sheet production lines in order to calculate the system performance due to Beta emitter sources with different energy distribution and select the suitable Beta emitter source. The relative error percentage, standard deviation, resolution, and contrast parameters for ¹⁴⁷Pm energy distribution were calculated 1.413, 0.113, 0.007, and 0.008, respectively. Also, these parameters for ⁸⁵Kr energy distribution were measured 2.750, 0.220, 0.014, and 0.001, respectively. The results reveal that the ¹⁴⁷Pm energy distribution has superior in comparison with the ⁸⁵Kr energy distribution for measuring of films or sheets with thin thickness.

The electrical capacitance tomography (ECT) is a visual nondestructive testing technology. The relative positional distribution between the electrodes and the phantom object affects the accuracy of the reconstructed image. To solve this problem, an image reconstruction method and image fusion algorithm of ECT system based on rotating electrodes are proposed. First, 4 image reconstruction algorithms are employed to reconstruct the experimental model, the Landweber iterative algorithm based on Tikhonov regularization presents the best performance. Then, by rotation the 12 electrodes 4 times, we can obtain 5 sets of capacitance data, and obtain 5 images. Finally, the fusion results can be obtained by performing the adaptive weighted fusion on these 5 images. Results show that the adaptive weighted image fusion method based on rotation electrodes improves the quality of reconstructed images and effectively reduces the artefacts.

Static tests of AFM carbon fiber samples made by autoclave and vacuum molding methods were carried out. Acoustic (acoustic emission and ultrasonic) methods, strain gauging, and microanalysis of thin sections were used to test for defects. The location of acoustic emission signals in the area of stress raisers made it possible to establish that the number of defects in autoclave molding is ten times less than under vacuum molding. Ultrasonic and acoustic emission methods, strain gauging, and microanalysis allowed determining the structure of AFM carbon fiber, the coordinates of defects, and their type. During the testing of unloaded samples made by vacuum molding, manufacturing defects were found that grew in size during static stretching and led to the occurrence of new destructions. No manufacturing defects were found in the samples produced by autoclave molding. Microanalysis of samples produced by the vacuum method revealed defects associated with fiber destruction, matrix cracking, and delamination. Tests of samples prepared by autoclave molding have shown that there are practically no defects in them.

A comprehensive experimental study was conducted on EN8 steel samples subjected to hot rolling at various temperatures and with different numbers of passes. The research investigates the influence of these rolling parameters on the material’s microstructure, hardness, and magnetic properties. The study includes controlled heating to specific temperatures, precise adjustments of roll spacing, and meticulous monitoring of rolling parameters. Key findings include the microstructural evolution during hot rolling, with grain refinement and phase transition, notably influenced by temperature. The data also reveals the relationship between rolling conditions, material hardness, and percentage of recrystallization, offering insights into optimizing material properties. Furthermore, the study presents an in-depth analysis of the Barkhausen peak’s behavior concerning temperature, showcasing its potential for non-destructive hardness evaluation. Overall, this research provides valuable knowledge for material engineers and manufacturers aiming to tailor EN8 steel properties through optimized rolling and heat treatment processes.