Russian Journal of Nondestructive Testing最新文献

Industrial images comprise complex configurations and their accurate segmentation is crucial for facilitating the delineation, characterization, and extraction of the region of interest. The edge-based level set (ELS) approach is one of the most often used in this field, but its main problem is the sensitivity to the initial position contour. In this work, we propose a hybrid image segmentation model using adaptively regularized kernel fuzzy technique (ARKF) integrated with edge-based level set function to solve this problem and enable welding defect detection. More specifically, our ARKF-ELS model comprises three key stages. The first stage applies the kernel fuzzy technique to isolate the cluster containing welding defects (regions of interest (ROIs)) from input image. In the second stage, this cluster is used to initialize the ELS method. In the third stage, the ARKF-ELS model is adopted to extract the weld defects. Experimental results on X-ray images demonstrate that the ARKF-ELS model can effectively extract regions of interest (ROIs) and confirm its efficiency in welding defects segmentation.

One of the promising methods of nondestructive testing for detecting substances that are similar in chemical composition and density is dual-energy X-ray image processing. In particular, dual-energy transformation algorithms can be applied to search for minerals hidden in waste rock. The method is most effective when the conditions for capturing X-ray images and energy levels are chosen correctly. This study compares the effectiveness of image processing using the dual-energy method in three cases of spectrum composition modification: first, by adjusting the voltage on the X-ray tube; second, by attenuating low-energy radiation using a copper filter; and third, by combining these methods. Fragments of beryl embedded in crushed muscovite were used as detection samples. A pulsed X-ray source that generates nanosecond-duration radiation pulses was used in this study. An original high-voltage generator circuit was implemented for the method of controlling radiation energy by varying the peak voltage on the X-ray tube. The use of such X-ray sources allows for obtaining high-resolution X-ray images of moving objects.

Imaging with linear array detectors based on fan-shaped X-ray beams can lead to abnormal data and image distortion due to the splicing of detector head (DH) boards. To solve the problems, in this paper a correction method is proposed for digital radiography (DR) imaging with linear array detectors based on fan-shaped X-ray beams. Firstly, the dynamic scaling method is employed to eliminate numerical bias of the linear regression fitting, thereby correcting the abnormal projection data. This method effectively reduces vertical bright line interference in imaging results and improves the quality of DR images. Secondly, to address the issue of position diffusion in DR images, the arcdegree adaptive compression (ADAC) algorithm is used to determine the optimal imaging area, adaptively correct the position relationship between the detection array and the DR image pixels, and reconstruct images proportionate to the size of the object under test. The experimental results indicate that the method proposed in this paper can effectively remove the abnormal values caused by DH boards splicing and generate DR images consistent with the original object scale, providing an effective data correction and image reconstruction method for imaging with linear array detectors based on fan-shaped X-ray beams.

While woven fabric is integral to carbon fiber reinforced polymer (CFRP) plates manufacturing, there has been a notable absence of research focused on the nonlinear detection of CFRP woven fabric. This article employs nonlinear acoustic methods to assess the response of CFRP plates, including unwoven, twill weave, and plain weave structures, to surface microcrack damage. A set of air-coupled nonlinear ultrasonic automatic detection systems was designed to acquire the amplitudes of the fundamental frequency and the second harmonic in the received signal, enabling the calculation of relative nonlinear parameters. Furthermore, the nonlinear cumulative effect was verified by varying the propagation distance. The experimental results highlight the significant influence of woven fabric on the outcomes of nonlinear acoustic testing. Specifically, the nonlinear response of unwoven CFRP to microcracks is the most pronounced, followed by twill weave CFRP plates. Notably, plain weave CFRP can significantly hinder the effectiveness of nonlinear acoustic detection. In cases where CFRP plates are loaded with such woven fabric, there is a potential for lower relative nonlinear parameters when damaged compared to their healthy state.

At present, the commonly used three-dimensional shape measurement technology of large-sized workpieces has the problems of poor robustness, low measurement efficiency and high cost. In order to solve the above problems, we propose a new measurement method which combines linear structured light and stereoscopic tracking. This paper mainly describes the linear structured light measurement system. A secondary extraction algorithm is designed based on the normal direction according to the commonly used laser stripe center line extraction algorithm. The algorithm improves the Gaussian curve fitting method. By combining the fine state refinement method, Hessian matrix method, Gaussian curve fitting and light plane calibration, the fast extraction of the center line of the laser stripe is completed, and the mapping relationship between the two-dimensional coordinates of the points on the laser center line and the three-dimensional coordinates in the camera coordinate system is obtained. We conducted feasibility experiments, and the preliminary experimental results indicate that this approach is valid, with measurement errors controlled within 0.44%.

When performing ultrasonic testing of pipes of various diameters using antenna arrays and matrices, two technologies for imaging reflectors—the total focusing method (TFM) and the digital aperture focusing (DAF)—are widely used. If the pipe diameter is greater than a hundred wavelengths, the DAF can be utilized for reflector imaging, considering multiple reflections from boundaries while assuming that the test object is flat. The errors in forming the DAF image of reflectors will be minimal in this case. However, if the pipe diameter is several tens of wavelengths and the wall thickness is approximately half the pipe diameter, then to obtain a quality DAF image of the reflectors, the geometry of the test object must be taken into account. This paper examines the features of image formation when recording echo signals with an antenna array or matrix while scanning both the outer and inner surfaces of the test object. Numerical and model experiments demonstrate that to achieve high-quality DAF images of reflectors when scanning the outer surface of a thick-walled pipe with a small diameter, both an antenna array and an antenna matrix can be used. This is due to the presence of the physical focusing effect of the ultrasonic field. However, when scanning the inner surface of a thick-walled pipe with a small diameter, echo signals must be recorded using an antenna matrix to reconstruct the image of the reflectors due to the defocusing effect.

A review of defect types in the production of corundum ceramic tiles and conventional methods for testing the integrity of products made from this material has been conducted. The integrity of tiles containing artificial defects was studied using the active thermal testing method with pulsed optical heating. A two-sided thermal testing setup was employed with software processing of the initial thermograms using Parker’s method. It was established that the best results for detecting internal defects in 10 mm thick ceramic tiles during thermal stimulation with xenon lamps are achieved by the two-sided thermal testing method with the construction of thermal diffusivity maps.

Resonant converters operate by using the natural behavior of certain components to minimize switching losses. These converters have the Soft Switching Characteristics which reduces the stress on the devices and leads to higher efficiency. The family of hybrid resonant converters includes the advantages of series and parallel resonant converters. LCC resonant converter is a type of resonant power converter that leverages a combination of series and parallel resonant elements to achieve soft switching and improved efficiency in high-frequency power supply applications. In this work, LCC resonant converter is simulated in open loop and closed loop with PID controller and fuzzy logic controller. The Converter is studied for operation in different modes and state Space Modeling is done. Transfer Function is obtained for the modeled converter. The converter is also examined for stability with location of poles and zeros in root locus and Bode plot. Entire software analysis is done in MATLAB Simulink.

This study presents an optimal probe structure for rapid and reliable measuring of the “Directional Barkhausen noise” (DBN). The dependence of barkhausen noise on a rotating magnetic field is an efficient measure for the evaluation of residual stress, magnetic anisotropy and magnetocrystalline energy. Barkhausen noise has a nonlinear relationship with the intensity of the magnetic field, therefore, to ensure the accuracy of this test, it is necessary to be sure that the intensity of the field remains constant during rotation. In practice, it is not possible to measure magnetic flux inside the material, but it can be estimated by using simulation tools at any point of the sample or the excitation core. Three kinds of probe structures to generate a uniform rotating magnetic field are proposed and analyzed. These probes enable continuous measurements in any direction and provide a more comprehensive characterization of material properties. Subsequently, the related experimental setup was implemented based on the optimal design of the probe that produces a uniform rotating magnetic field.

Additive manufacturing has been playing a significant role in the manufacturing of components with complex geometries for aerospace applications recently. Comprehensive nondestructive testing techniques (NDT) are vital for the successful quality evaluation of critical components in this domain. Appropriate selection of the NDT scheme is essential for the qualification of such components. Major NDT techniques are designed based on the interaction of electromagnetic radiation and the response of the sound or heat energy transmission or reflection from the test object. The common defects noticed in the components made through additive manufacturing (AM) routes are pores, clusters of porosities, micro-cracks, lack of fusion and layer delamination. Considering the morphology and the complications in the geometry of aerospace components, many conventional NDT techniques are unsuitable for the inspection of AM components. Detection of unfused powder in the AM components by conventional radiography is difficult due to the low radiation attenuation coefficient gradient between the unfused and fused metallic regions. Also, the detection of defects in the radiography technique depends entirely on the beam path. Multiple radiography images with different beam angles and film combinations are essential to get the maximum information on the defects by conventional radiography techniques. In this aspect, computed tomography, a noncontact NDT technique provides a better solution for determining embedded defects such as lack of fusion and layer separation due to presence of unfused powder in the AM components. The present study compares the capability of computed tomography and 2D digital radiography for the identification of lack of fusion defects in stainless steel SS316L specimens fabricated through the Laser powder bed fusion AM route.