Open Access
Access granted
Subscription Access
No 3 (2023)
Articles
On improving the efficiency of the pass-through electromagnetic-acoustic transducer of longitudinal waves
Abstract
The paper theoretically and experimentally investigates the possibility of increasing the efficiency of pass-through electromagnetic-acoustic (EMA) transducers of longitudinal waves when changing the direction of current in a high-frequency inductor and forming a co-directional (counter-directional) switch of the magnetic field of the inductor relative to the polarizing field of constant magnetization. It is shown that the increase in the EMA conversion efficiency due to the electrodynamic mechanism is due to a local increase in the eddy current density along the edges of the aperture of the high-frequency inductor when the magnetic field is turned on counter-directionally. These patterns are most evident for samples with high
Defektoskopiâ. 2023;(3):3-13
3-13
Acoustic emission cluster analysis of composite laminates with different interfacial fiber orientations based on gaussian mixture model
Abstract
The present study aimed to find a method with higher efficiency to cluster acoustic emission events. The acoustic emission signals of composite laminates with different interfacial fiber orientations were captured during the Double cantilever beam (DCB) experiments. Through feature selection of the preprocessed data using the Relief F algorithm, it was found that most of the information in the acoustic emission signals can be represented by the amplitude, inverse frequency, center frequency, peak frequency and so on. Subsequently, principal component analysis and expectation-maximization and Gaussian mixture models were adopted to cluster the data with reduced dimensions. This method can not only distinguish among different damage mechanisms but also show the level of damage concentration according to their types. Furthermore, once the clusters were assigned to different damage mechanisms, they could be identified precisely using both the amplitude and peak frequency. Finally, based on the loading curves of the four types of specimens, the cumulative events and energies of the acoustic emission were compared and analyzed, and different damage mechanisms were identified.
Defektoskopiâ. 2023;(3):14-30
14-30
Nondestructive evaluation by eddy current and ultrasonic technique of 475�C embrittlement effects in dss duplex stainless steels and corrosion behavior
Abstract
In this paper, a non-destructive evaluation of the embrittlement effect in duplex stainless steel DSS 2205 aged from 5 h to 100 h at a temperature of 475 ° C was performed by Eddy current and ultrasonic techniques, in addition the corrosion behavior was carried out after heat treatment at 475°C. The experimental results show that an inverse behavior was observed between normalized impedance and hardness in aging time at 475°C; when the normalized impedance of the Eddy current probe was decreased, hardness was increased with aging time. The longitudinal ultrasonic velocity and transversal velocity were calculated in this study for each sample. The Young’s modulus and the Shear modulus were computed from the two velocities. The investigation carried out shows a sensitivity of Eddy current and ultrasonic technique to the microstructure changing observed at 475 ° C, due to embrittlement in duplex stainless steel. The effect of heat treatment at 475°C on the corrosion behavior was also evaluated by Eddy current on a long time and revealed the important changing in corrosion resistance due to spinodale decomposition of the ferrite phase.
Defektoskopiâ. 2023;(3):31-43
31-43
Optimization algorithm for sandwich detectors of x-ray radiation
Abstract
Приводится описание алгоритма оптимизации параметров сэндвич-детекторов рентгеновского излучения применительно к распознаванию материалов методом дуальных энергий. Применение алгоритма проиллюстрировано на конкретном примере, где были получены значения толщин первого детектора и промежуточного фильтра (входящих в состав сэндвич-детектора), которые для заданных материалов первого детектора (CsI) и промежуточного фильтра (Cu) являются оптимальными при распознавании взрывчатых веществ.
Defektoskopiâ. 2023;(3):44-58
44-58
Three-dimensional tomography of scattering inhomogeneities by a cylindrical multistatic probing system
Abstract
A method of three-dimensional ultrasonic tomography based on multi-view probing with multiple emitters and multiple receivers on a cylindrical surface in a wide frequency band is proposed. Emitters and receivers are placed on a ring that moves along the vertical axis. Signal processing is based on the use of matched filtering and is reduced to the calculation of cyclic convolution along the angle and vertical axis, which makes it possible to implement a fast algorithm for recovering of three-dimensional images. To test the method, an experimental setup was developed consisting of 32 emitters and 64 receivers uniformly placed on a ring with a radius of 205 mm. During the experiments, sounding was carried out in air at frequencies from 38 kHz to 43 kHz. As a result, a three-dimensional object of a complex shape is visualized, which confirms the applicability of the proposed method.
Defektoskopiâ. 2023;(3):59-65
59-65