编号 6 (2024)

Samples from domestic ACM carbon fiber made by autoclave and vacuum forming under static loading were studied. To control defects, acoustic methods (acoustic emission, ultrasonic), strain metering were used and microanalysis of their thin sections was carried out. The location of acoustic emission signals in the region of the stress concentrator made it possible to determine that in autoclave molding their number is ten times less than in vacuum. The ultrasonic method and acoustic emission made it possible to determine the structure of carbon fiber, the coordinates of defects and their type. During the control of unloaded samples made by vacuum molding, manufacturing defects were found that, when stretched statically, increased in size and led to the initiation of new failures. In autoclave-formed samples, manufacturing defects were not found. Microanalysis of vacuum samples revealed defects associated with fiber failure, matrix cracking, and delamination. Autoclave tests showed that the number of defects and their dimensions were significantly reduced.

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.

The creation of 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 mathematical expectation of maximum likelihood (maximum likelihood expectation MLEM) is considered. 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 methods of image reconstruction, being the foundation for many other approaches. A new version of the MLEM parallel algorithm is proposed, which provides global convergence of the iterative algorithm. To parallelize the algorithm, the texture mapping method is used 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 non-destructive testing of various industrial products, including testing of foundry products.

This article is a continuation and addition of the article with the same title published in the journal «Defectoscopiya» No. 1 for 2022, which provides six ways to assess the quality and reliability of semiconductor products (SCP) using low-frequency (LF) noise parameters. This article presents a generalization of the results previously obtained by the authors and describes four more methods for diagnosing and evaluating the reliability of SCP by changing 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 reliability of the SCP.

The complex of works on the diagnostics of changes in the material properties due to aging includes accelerated climatic tests (ACT) and performance tests before and after ACT. Along with the use of various methods for diagnosing defects that arise and develop during aging, it is also important to determine the changes in the thermophysical, moisture-physical and other properties of materials that have passed long-term operation associated with the processes of changes in the material structure. In addition to the method of synchronous analysis of changes in the thermophysical and moisture-physical properties of materials due to aging and corresponding corrections to changes in the heat and humidity conditions of products during long periods of operation and storage, an experimental facility and a method for experimental and analytical determination of the thermophysical properties of materials at variable heating rates based on the results of thermal tests of samples that have passed and have not passed ACT, using the approximation-superposition method in the analysis of test results to solve the inverse problem of thermal conductivity.

The article describes the non-conductive coating thickness simulating system, designed for automatic graduation of the coating thickness gauge using a large number of graduation points. The accuracy of the non-conductive coating thickness simulating system has been evaluated. The procedure for graduation of the coating thickness gauge is described, taking into account the design features and ways to compensate for the main sources of errors of the non-conductive coating thickness simulating system.

Optimization of magnetizing devices’ standard sizes is relevant for solving magnetic control problems. In order to obtain detailed information and feature about spatial distribution of field and flux in the control zone, a closed magnetic circuit “attachment transducer — control object” was modeled. The models with different design features of the dowel transducer were considered. Samples with different magnetic properties were used as objects for investigation. The results of data processing showed the asymmetry of the distribution of the tangential component of the magnetic field strength in the control zone at the design of the transducer with one slot.