Showing papers in "Russian Journal of Nondestructive Testing in 2020"
TL;DR: In this article, a variational decomposition of signal and a deconvolution method are used to improve the resolution of ultrasonic phased array for defect detection and make the detection process as fast and accurate as possible.
Abstract: Over the past few years, the use of ultrasonic arrays for nondestructive testing (NDT) applications has grown rapidly and led to use new algorithms of signal processing. The present paper’s main objective is to improve the resolution of defect detection and make the detection process as fast and accurate as possible. This paper introduces a novel method to improve the resolution of ultrasonic phased array. The proposed method is based on the variational decomposition of signal and on a deconvolution method. To reduce the level of signal’s noise, a method based on the variational mode decomposition (VMD) is used and to improve the resolution, a sparse deconvolution algorithm optimized using the majorization-minimization (MM) method is used. A simulation study has been carried out simulating a block of stainless steel containing several defects in different positions. Experimental tests were performed on a sample of stainless steel containing several defects. The obtained results show that the proposed method can improve the quality of ultrasonic data which enhances the localization of defects.
10 citations
TL;DR: In this article, the impact of defects on similar sheets and dissimilar sheets used in the automotive industry was investigated by using finite element method for non-destructive tests on spot welding, which is one of the types of resistance welding used in this experiment for sheet welding.
Abstract: This paper investigates the impact of defects on similar sheets and dissimilar sheets used in the automotive industry. Spot welding is one of the types of resistance welding used in this experiment for sheet welding. The thickness of sheets welded by the spot welding method can be between 0.5 and 3 mm. In this paper, the simulation is performed by finite element method for non-destructive tests on spot welding. This study investigated the propagation of ultrasonic waves in two similar layers of stainless steel and galvanized stainless steel sheets and two dissimilar layers of stainless steel sheets and galvanized stainless steel sheets in different thicknesses. This test was performed by ultrasonic immersion method and the intensity and amplitude of the reaction of the resulting defect waves and its effect on the results were also investigated. Due to the performance of finite element method softwares, Comsol Multiphysics software because of its high accuracy used. It has been studied various factors and conditions including excitation frequency, boundary conditions, the most suitable position for the probr Fto stimulate the waves, focused or unfocused waves in the simulation, sensitivity analysis of mesh size and appropriate mesh size for simulation. In this paper, the joint of similar sheets and dissimilar sheets is investigated. For this performance, the average relative error that can meet the industrial requirement is mentioned. The results of the simulation with the results of the experimental test They were compared and investigated And with the amount of error tests, have acceptable results and it can be used with the error specified and can meet the needs of the automotive industry.
10 citations
TL;DR: In this paper, a two-spar T800 CFRP wing box has been tested using the methods of acoustic emission (AE) and strain gaging in real time in the areas where strain gages were bonded (the panels of wing box, the walls of side members and the shelves of stringers).
Abstract: Static tests of a two-spar T800 CFRP wing box have been carried out. The object was tested when loaded using the methods of acoustic emission (AE) and strain gaging. Strain in the material was determined in real time in the areas where strain gages were bonded (the panels of wing box, the walls of side members, and the shelves of stringers). The elements of the wing box have been established in which nonlinear strain change is observed and residual deformations are recorded after unloading. The AE method has been used to localize the sources of signals. The coordinates of the sources corresponded to the location of the third rib. Clustering recorded AE signals based on their digitized form has made it possible to group the signals and assign them to sources that correspond to structure failure. It is shown that in the process of loading the wing box, an increase in the structural coefficient of AE signals corresponding to CFRP delamination in the location zone is observed.
8 citations
TL;DR: Algorithms are proposed for modeling the spatial outlines of test objects and forming their images in digital radiography systems, which provide the basis for simulation models of the systems being analyzed.
Abstract: —Algorithms are proposed for modeling the spatial outlines of test objects and forming their images in digital radiography systems. The algorithms provide the basis for simulation models of the systems being analyzed. The simulation models are designed to substantiate the technical feasibility of monitoring objects and selecting the parameters and evaluating the characteristics of digital radiography systems. To illustrate the capabilities of the developed simulation models, the digital radiographic images of some objects have been produced, including those of reference samples of sensitivity, spatial resolution, resolving ability, and penetrating power.
8 citations
TL;DR: In this article, a nondestructive eddy current method has been used to characterize microstructural features of Hadfield steels subjected to various conditions of heat treatment, including quenching media (furnace, air, and water) and tempering temperatures (in the range of 200-600°C) were varied to obtain different microstructures.
Abstract: A nondestructive eddy current method has been used to characterize microstructural features of Hadfield steels subjected to various conditions of heat treatment. The heat treatment parameters including quenching media (furnace, air, and water) and tempering temperatures (in the range of 200–600°C) were varied to obtain different microstructures. X-ray diffraction method, scanning electron microscopic observations, and hardness testing were utilized to characterize the phases formed in microstructure and mechanical properties. Quantitative values of carbide and pearlite structures were determined using an image processing software applied on microscopic images. Effect of microstructural features (type, fraction, and morphology of the formed phases) on the eddy current outputs (RMS voltage, normalized impedance, and phase angle) have been evaluated. The study demonstrates that the eddy current method could be used to detect microstructural changes of heat treated Hadfield steel, nondestructively. The results also show correlation coefficients of over 93% in determining austenitic matrix fraction by eddy current technique.
8 citations
TL;DR: The proposed method in this paper is combination threshold and multistage watershed technique that applies to detect some of welding defects such as lack of fusion, wormholes, incomplete filled groove, and incomplete penetration.
Abstract: In this work proposes a technique to detect some types of defects based on the radiography method. Inspection tests include two categories, destructive and nondestructive. One of the nondestructive tests is radiographic test that is used to detect internal defect. In addition, the image processing methods are used to improve defect detection in the radiographic images. The watershed technique is one of the segmentation methods that used to analyze images based on needed information. The proposed method in this paper is combination threshold and multistage watershed technique that applies to detect some of welding defects such as lack of fusion, wormholes, incomplete filled groove, and incomplete penetration. Otsu’s threshold leads to an increase in the contrast of the image and then multistep watershed transformation used to detect discontinuities and defect welding.
7 citations
TL;DR: The efficiency of the vibroacoustic modulation method in the detection and evaluation of flanged joints of simulated wind turbine towers has been numerically investigated by defining an index for modulation intensity and bond relaxation.
Abstract: Flanged joints’ looseness is among the common causes for the failure of industrial structures with flanged joints such as wind turbine or transmission line pipes the timely detection of which can prevent the imposition of heavy, financial losses and in some cases property damage. Conventional methods for detecting this fault, such as torque control methods, have high error of measurement, or impedance-based measurement methods, have high expenses, or vibration or ultrasonic methods which lack accuracy due to the use of linear phenomena in fault detection. Vibroacoustic modulation method is one of the nonlinear fault detection methods that detect and evaluate looseness of flanged connection with high precision through the measurement of the intensity of the vibrational and ultrasonic signals modulation applied to the structure. Although the published papers in recent years have often identified the cracking, delamination, or corrosion and decay of parts using this method, in this paper the efficiency of the vibroacoustic modulation method in the detection and evaluation of flanged joints of simulated wind turbine towers has been numerically investigated by defining an index for modulation intensity and bond relaxation. Then, the effect of parameters such as ultrasonic and vibrational frequency, amplitude of ultrasonic and vibrational stimulation, sensors and actuators position, as well as preload force, on the method performance have been studied. Finally, in order to reduce the simulation time in ABAQUS software, the modeling of the neural network was performed using MATLAB software and the obtained results were compared with numerical results.
7 citations
TL;DR: In this article, the results of applying laser-ultrasonic and acoustic-emission nondestructive testing techniques to study the processes of deformation and fracture of friction-stir-welded joints are presented.
Abstract: The results of applying laser-ultrasonic and acoustic-emission nondestructive testing techniques to study the processes of deformation and fracture of friction-stir-welded joints are presented. The load-strain diagrams were obtained and the mechanical characteristics of the samples of welded joints made of an aluminum-magnesium alloy were determined. The laser ultrasonic method, based on the acoustoelasticity effect, was used to measure the mechanical stresses arising in welded joints during uniaxial loading of specimens in the elastic range. Acoustic emission signals arising during the tension strain of the samples of welded joints were recorded. It has been established that the nature of the distribution of the parameters of acoustic emission occurring during the destruction of faulty welded joints has some distinctive features. The activity and total acoustic-emission count were considered as informative parameters under the conditions of static uniaxial loading of the samples of welded joints.
6 citations
TL;DR: In this paper, a combined method for thermal nondestructive testing using optical and ultrasonic stimulation by means of combining individual thermograms obtained at the corresponding time points is proposed.
Abstract: We propose a combined method for thermal nondestructive testing using optical and ultrasonic stimulation by means of combining individual thermograms obtained at the corresponding time points. The resulting sequences of infrared thermograms provide more efficient identification of defects of various types and can also be processed using well-known algorithms, for example, thermographic signal reconstruction, principal component analysis, etc. We obtained experimental results on a composite CFRP sample imitating aircraft ribs using a robotic manipulator.
6 citations
TL;DR: In this article, the authors proposed to use the tip of vertical drillings to simulate defects weakly scattering ultrasound, which can increase the sensitivity of ultrasonic testing by at least 6 dB, i.e., two times or more.
Abstract: Issues of quality control of welded joints in hot-tool butt-welded polyethylene pipelines are considered. It is indicated that the main scope of control currently falls on inspections based on the parameters of welding and on selective mechanical testing of welded joints. Physical nondestructive post-welding testing methods are used little, which is generally not typical for the practice of testing welded joints. The reason for this is the general problem of ultrasonic methods, viz., the low detectability of contracted defects, partially transmitting ultrasound. To ensure the detectability of such defects, we evaluate the possibility of increasing the sensitivity of ultrasonic testing by using the ultrasonic time-of-flight-diffraction (TOFD) technique. It is proposed to use the tip of vertical drillings to simulate defects weakly scattering ultrasound. It is shown that when tuning is performed based on such targets, the inspection sensitivity can be increased by at least 6 dB, i.e., two times or more. In this case, the drilling tip can simulate the upper and lower edges of a planar defect vertically oriented in the section of the weld. The results of experimental studies aimed at revealing multidirectional drills with a diameter of 1 mm in welded seams of polyethylene pipes, including pipes with an additional removable outer layer, are presented. The expediency of gathering statistical data on the identification of real defects in welded butt joints of polyethylene pipes using the considered testing method is shown.
6 citations
TL;DR: In this article, a flexible sensor consisting of a replaceable flat cable with connectors at the ends is designed, followed by the analyses of sensor offset and liftoff effects to distinguish the unevenness of accumulation, the sensor-coil array scheme is proposed and the output array signals successfully characterize the profile of inner accumulation.
Abstract: Austenitic boiler tubes are key components in modern coal-fired power plants but often suffer from blockage or even rupture caused by the accumulation of steam-side oxide scales Existing nondestructive testing methods are somewhat deficient to quantify the accumulated height of exfoliated oxide scales Pulsed eddy current (PEC) technique has unique merits such as deep penetration depth and diverse signal features, offering a great possibility to address this issue This work serves as an exploratory study for applying PEC technique to measure the scales accumulation Finite element modeling and experimental work are conducted to validate the feasibility and effectiveness of PEC measurement under different circumstances The PEC signal peak shows a linear relationship with the accumulated height and thereby is used as the signal feature for the quantitative measurement of accumulated height A flexible sensor consisting of a replaceable flat cable with connectors at the ends is designed, following by the analyses of sensor offset and liftoff effects To distinguish the unevenness of accumulation, the sensor-coil array scheme is proposed and the output array signals successfully characterize the profile of inner accumulation Finally, a referencing strategy is explained to eliminate the interference due to magnetism transformation of the tube wall
TL;DR: In this paper, a series of two-dimensional models of bored piles without defects, with or without soil inclusions, or with debonding of the access tubes from the concrete.
Abstract: Noncompliance of the form or material of piles with the requirements of project documentation may lead to an unacceptable decrease in the bearing capacity of the foundations of buildings and structures being constructed. Field tests are carried out using nondestructive geophysical methods in order to control the quality of cast in-situ reinforced concrete piles. Ultrasonic monitoring of concrete integrity is based on the analysis of the parameters of elastic waves excited and recorded in the pile body using sensors immersed in the access tubes installed in the reinforcement cage. Numerical simulation of the propagation of elastic waves has been performed to clarify approaches to the interpretation of ultrasonic data in the COMSOL Multiphysics software. The studies were conducted for a series of two-dimensional models of bored piles without defects, with soil inclusions, or with a debonding of the access tubes from the concrete. Conclusions are drawn about the possibilities and limitations of the method. The influence of the location and geometrical dimensions of defects and of the violation of adhesion of access tubes to concrete on the results of measurements is demonstrated. The need for additional research of anomalies by crosshole tomography prior to drawing conclusions about the possibility of further use of the piles as part of a foundation is indicated. General recommendations are given regarding the number of access tubes to be arranged in a pile and the choice of time interval for calculating the attenuation. It is shown that it is incorrect to calculate the strength of the pile material from the values of wave propagation velocity.
TL;DR: In this article, the authors proposed algorithms for processing signals obtained by the multiple shadow method using Rayleigh waves propagating in the direction of the pipe envelope and electromagnetic-acoustic emission-reception technique.
Abstract: We propose algorithms for processing signals obtained by the multiple shadow method using Rayleigh waves propagating in the direction of the pipe envelope and electromagnetic-acoustic emission-reception technique. The results of studying the method susceptibility to artificial and natural surface and near-surface defects of workpieces intended for the production of drill pipes in two-frequency ranges are presented. The multiple detection coefficient and the probabilistic characteristics of variance, asymmetry, and kurtosis are proposed to be used as informative parameters in analyzing the series of multiple signal passes. The rejection criteria are substantiated. The research results can be used in the development of automated units and methods for monitoring small-diameter pipes.
TL;DR: This article has validated the developed model and then determined directly the crack length by analyzing the complete signal and extracting from the complete sensor sweep signal the maximal amplitude that is exploited to estimate the crack depth.
Abstract: The study of 3D eddy current non destructive testing system for cracks characterization using finite element method requires a great amount of computing time and memory space. In this article, we have validated the developed model and then determined directly the crack length by analyzing the complete signal. Afterwards, we have extracted from the complete sensor sweep signal the maximal amplitude that we have exploited to estimate the crack depth.
TL;DR: In this article, the effect of the size and shape of cutouts in steel plates on the difference in the arrival time of acoustic emission pulses at receiving transducers was compared with the results of a numerical simulation of the propagation of elastic waves in plates with various strip and circular cutouts.
Abstract: Experiments have been carried out to study the effect of the size and shape of cutouts in steel plates on the difference in the arrival time of acoustic emission pulses at receiving transducers. The data obtained were compared with the results of a numerical simulation of the propagation of elastic waves in plates with various strip and circular cutouts. The research results indicate that the shape of the cutout has a much lesser effect on the time of recording pulses by the transducers of an antenna array than the size of the cutout and the location of the receiving transducer relative to the shading zone—the edge of the cut-out. Based on the results of studies in a 40-mm–thick steel plate with a central 100 mm hole, the accuracy of locating an acoustic emission source near the edge of the hole was estimated. Studies have shown that, in this case, to reduce the measurement error to less than 10% of the antenna-array base size, the location group must include at least four transducers. Numerical simulation of the propagation of acoustic emission pulses in plates with strip and circular cutouts made it possible to significantly reduce the volume of experimental studies, while increasing their information content.
TL;DR: In this article, the influence of microstructure on residual stress of self-reacting friction stir weld joint measured with longitudinal critically refracted wave was discussed, and two longitudinal critically-refracted wave transducers, the spacing between which was fixed, were used, then the acoustoelastic formula was optimized, and difference in time of flight between longitudinal critically re-racted wave, which replaced propagation velocity as characteristic parameter for residual stress measurement, was determined by the cross correlation theory.
Abstract: Correction method for microstructure effect on residual stress of self-reacting friction stir weld joint measured with longitudinal critically refracted wave was discussed in this study. Two longitudinal critically refracted wave transducers, the spacing between which was fixed, were used, then the acoustoelastic formula was optimized, and difference in time of flight between longitudinal critically refracted wave, which replaced propagation velocity as characteristic parameter for residual stress measurement, was determined by the cross correlation theory, at last the influence of microstructure on residual stress of self-reacting friction stir weld joint was solved. Results show that as stress increases, the deviation in difference in time of flight becomes obvious, and when stress reaches stress turning point, experimental result is not agreed with the acoustoelastic theory as stress increases further. Step length is an important factor for difference in time of flight, and one cycle is seen as optimal step length. For acoustoelastic coefficient, the value of nugget zone is biggest, and the value of (heat affected zone + thermal mechanical affected zone) is smallest, in addition, the value of advancing side is slightly bigger than that of retreating side. Finally, residual stress of self-reacting friction stir weld joint was corrected with longitudinal critically refracted wave, and the result is verified by hole-drilling.
TL;DR: In this article, the authors proposed to increase the speed by simultaneously emitting probing signals by all elements of an antenna array (AA), formed according to the sets of code sequences used in the CDMA technology.
Abstract: The disadvantage of using the digital focusing with an antenna (DFA) method to produce an image of reflectors is a large volume of echo signals and an insufficiently high speed of their recording. We propose to increase this speed by simultaneously emitting probing signals by all elements of an antenna array (AA), formed according to the sets of code sequences used in the code division multiple access (CDMA) technology. The measured echo signals can be decoded using matched filtering (MF) and the reflectors can be reconstructed using the combined SAFT (C-SAFT) method. The image can be reconstructed without decoding the measured echo signals using the ME method. The proposed technology was tested to obtain images of reflectors in samples of duralumin, steel 20, and steel 40.
TL;DR: In this paper, the authors used ground penetrating radar (GPR) profiling method to detect grouting defects of bellows in reinforced concrete slabs, which can be used for the detection of box girders in bridge engineering.
Abstract: With the development of science and technology, the development of non-destructive testing is more and more mature, and Ground penetrating radar (GPR) has been widely used because of its advantages of fast detection speed, continuous detection process, high resolution, convenient and flexible operation, and low detection cost. However, it is rarely used in the detection of bellows defects. Therefore, the validity and applicability of GPR needs to be verified for detecting grouting defects of bellows in box girders. The box girder slab is simulated by placing bellows in the reinforced concrete slab. Ground penetrating radar (GPR) profiling method is used to detect grouting defects of bellows in reinforced concrete slabs. The two-dimensional and three-dimensional images of ground penetrating radar detection results are analysed. The results show that: Combining the X and Y direction detection images of ground penetrating radar, the specific location of the cavity defects in the bellows can be known. The three-dimensional slice of ground penetrating radar can roughly reflect the size of the internal cavity defect in the bellows. The two-dimensional and three-dimensional images of ground penetrating radar (GPR) can verify each other and complement each other when detecting the internal void defects of reinforced concrete plate corrugated pipe, which is helpful to grasp the internal defects of corrugated pipe in depth. The experiment proves that the ground penetrating radar is effective and promising for the detection of reinforced concrete plate bellows, and can be used for the detection of box girders in bridge engineering.
TL;DR: In this article, the results of automatic noncontact scanning of PCM products in the shadow mode using an adaptive measuring complex that allows the testing parameters to be adapted to each new tested product are presented.
Abstract: It has been shown that in order to increase the sensitivity of ultrasonic noncontact shadow testing of products made of polymer composite materials (PCMs), it is necessary, along with the well-known techniques (increasing the amplitude of the probing signal, using radio technical signal processing methods, employing highly sensitive electroacoustic transducers), to optimize the parameters of noncontact testing. Criteria have been established for choosing air gaps between the emitting transducer and the test object and between the test object and the receiving transducer, as well as criteria for choosing the duration of probing signals. Methods for increasing the reliability of testing the border regions of small-thickness PCM products are proposed. The results of automatic noncontact scanning of PCM products in the shadow mode using an adaptive measuring complex that allows the testing parameters to be adapted to each new tested product are presented.
TL;DR: In this article, a mathematical model is proposed for determining the quality of applying a heat-conducting compound, and simulation results are presented based on the theory of heat transfer in a solid.
Abstract: A mathematical model is proposed for determining the quality of applying a heat-conducting compound, and simulation results are presented. The model is based on the theory of heat transfer in a solid. The model has been verified using experimental data obtained by measuring the temperature at the points of contact of two bodies using thermocouples. It is shown that the data obtained using thermocouples coincide with the data obtained using thermopower.
TL;DR: In this article, the authors present the results of a study that confirms the high efficiency of using surface microwaves in assessing the extent of exfoliation of dielectric and magnetodielectric coatings from a metal base.
Abstract: We present the results of a study that confirms the high efficiency of using surface microwaves in assessing the extent of exfoliation of dielectric and magnetodielectric coatings from a metal base. The complex coefficient of attenuation of the field of a surface electromagnetic wave along the normal to the coating surface is used as a parameter for estimating the extent of exfoliation. In contrast to the existing approaches, the developed electrodynamic measurement model takes into account the real and imaginary parts of the complex dielectric permittivity and magnetic permeability of the coating with allowance for their frequency dispersion; this improves the accuracy and reliability of estimating the extent of exfoliation. An algorithm is developed for estimating the extent of coating exfoliation based on the search for the maximum joint probability density of the coefficient of attenuation of the field of a surface electromagnetic wave measured at a set of frequencies. We introduce and substantiate a statistical limit of the resolution of two values of exfoliation; this makes it possible to evaluate the possibility of discriminating between two close values of exfoliation depending on the bandwidth of attenuation coefficient measurements, their number, and the signal-to-noise ratio. The structure of a measuring complex that implements the proposed approaches to exfoliation assessment is provided. Numerical and field experiments have shown the fundamental possibility of estimating the value of recorded values of exfoliation of dielectric and magnetodielectric coatings from a metal substrate with a thickness of 20 μm or less in the frequency band of 9–13.5 GHz.
TL;DR: In this article, a method for estimating porosity of unidirectional carbon fiber composites based on measuring their acoustic impedances is proposed and experimentally implemented, which does not involve measuring the volume and mass of the object under study and can be used in diagnostics of complex shaped composite structures.
Abstract: A method for estimating the porosity of CFRPs based on measuring their acoustic impedances is proposed and experimentally implemented. The acoustic impedance of the test sample is derived from the magnitude of the antiderivative of an ultrasonic pulse reflected from the immersion-liquid–sample interface. The studied samples are unidirectional CFRPs with various volume contents of the matrix and filler. It has been established that the distribution of local porosity in the samples is uneven along the carbon fiber stacking plane. The value of porosity averaged over the results of optical–acoustic measurements with allowance for measurement errors is consistent with the X-ray tomography data. The method for estimating the value of porosity presented in this paper does not involve measuring the volume and mass of the object under study and can be used in diagnostics of complex shaped composite structures.
TL;DR: In this article, the characteristics of bond slip failure process of BFRP concrete are studied based on acoustic emission technology as a real-time dynamic nondestructive monitoring technique, and the results show that acoustic emission centroid frequency increased with the slip, the AE count ratio and the AE energy ratio is the largest at the stage of overcoming the chemical bonding force.
Abstract: The research on the bond slip characteristics of BFRP concrete mainly focuses on mechanical properties. There has been no effective technology to study the bond slip damage process of BFRP concrete. Therefore, the characteristics of bond slip failure process of BFRP concrete are studied in this paper based on acoustic emission technology as a real-time dynamic nondestructive monitoring technique. The results show that acoustic emission centroid frequency increased with the slip, the AE count ratio and the AE energy ratio is the largest at the stage of overcoming the chemical bonding force, and then it is significantly reduced and there is a certain increase at the peak of the load. The scatter diagram of the AE duration and the counts is concentrated in on region, likes two rays. Moreover, these phased stable characteristics of acoustic emission characteristics corresponding to different stages of BFRP concrete bond slip process, it provide evidently basis for identifying the process of BFRP concrete bond slip damage based on acoustic emission technology.
TL;DR: In this paper, an algorithm was presented for the sequence of changes in the total intensity of the magnetic field pulses on the aluminum plate surface that ensures the same amplitude of hysteretic electric-voltage oscillations and allows one to obtain a linear difference dependence for wedge-shaped and flat aluminum samples.
Abstract: Based on the developed methods of hysteretic interference, we produced the calculated dependences $$U\left( x \right)$$
of the electric voltage across a magnetic field transducer on the x-coordinate. A magnetic carrier with an arctangent characteristic was exposed to a series of one, two, three, four, five, and fifteen bipolar pulses of linear-inductor magnetic field. An algorithm is presented for the sequence of changes in the total intensity of the magnetic field pulses on the aluminum plate surface that ensures the same amplitude of hysteretic electric-voltage oscillations and allows one to obtain a linear difference dependence $$U\left( x \right)$$
for wedge-shaped and flat aluminum samples. The results obtained make it possible to improve the accuracy and efficiency of object thickness gaging and testing for thickness variation in the given directions, as well as for defects in the object.
TL;DR: In this paper, the feasibility of LSTM for fault detection using ultrasonic signals was studied and it was found that the overall accuracy for test data is 67.64%.
Abstract: Computer aided Interpretation of Ultrasonic signals depicting flaws in weld pieces is depicted in this work. In this work, feasibility of Long Short Term Memory (LSTM) for flaw characterization is studied. Owing to the advantage of LSTM, the first technique involves training LSTM directly with the signals as inputs and testing its ability to characterize the flaws from the input signals. Due to wide variation in the length of input sequences, which introduced sparseness in other sequences, overall accuracy is affected. Hence in the second technique, LSTM are trained with features of the signals and it is found that the overall accuracy for test data is 67.64%. These features are statistical parameters obtained from the approximation co-efficient of the input signals. The input signals are decomposed with a novel wavelet template.
TL;DR: In this paper, a mathematical model of the output signals of an X-ray sandwich detector is presented and two mathematical models of the radiation transparency of the test object for a sandwich radiation detector have been developed.
Abstract: A mathematical model of the output signals of an X-ray sandwich detector is presented. Based on this model, two mathematical models of the radiation transparency of the test object for a sandwich radiation detector have been developed. These models are the basis for a theoretical assessment of the accuracy of recognizing materials using the corresponding implementation scheme of the dual-energy method. The fundamental difference between the developed models is that one of them does and the other does not take into account statistical dependence between the output signals of the sandwich detector. Recommendations on the preference for using each of these models are given.
TL;DR: In this paper, the authors studied the joint dynamics of changes in the parameters of acoustic emission and in the friction coefficient during TRB friction machine testing of flat steel 12Kh2N4ASh specimens, including those with Ti + Al + N ion-plasma vacuum sputtering.
Abstract: We study the joint dynamics of changes in the parameters of acoustic emission (AE) and in the friction coefficient during TRB friction machine testing of flat steel 12Kh2N4ASh specimens, including those with Ti + Al + N ion-plasma vacuum sputtering. The results of studying the shape of the curve of the reconstructed values of AE-event stream intensity in different parts of the experimental curves of the dependence of friction coefficient on test time are presented. A significant correlation was discovered between the friction coefficient and the reconstructed AE-event stream intensity. Methods are proposed for evaluating the friction coefficient and the time of the run-in stage end based on the reconstructed AE-event stream.
TL;DR: In this paper, Tangential radiography technique (TRT) was used to measure the pit depth of a stepped steel pipe in an X-ray radiation source, which has good controllability and a lower impact on the human body than do γ-ray sources.
Abstract: The piping systems used for the transportation of liquids and gases in power stations, petroleum petrochemical facilities, and chemical plants are significantly impacted by corrosive processes. One of the most destructive forms of corrosion is pitting corrosion, which produces holes on piping metal surfaces. Monitoring pit depth is necessary in order to prevent leakage in the piping system, especially during operation. However, measuring pit depth as a part of periodical inspections is complicated since the pit depth on the outside wall of a pipe may vary. Non-destructive testing (NDT) methods such as ultrasonic, liquid penetrants, and magnetic particles are used to detect defects in industrial components; however, they first require the removal of insulation and the shutdown of the pipe system. Another alternative NDT technique, tangential radiography technique (TRT), offers a solution to this problem as tests can be conducted without removing piping insulation, allowing testing while the piping system is online. In this study, we tested TRT using an X-ray radiation source, which has good controllability (i.e., intensity and exposure time) and a lower impact on the human body than do γ-ray sources. We focused on the comparison of film density measurements using a density meter and a light meter. The magnification of pit diameter was used to obtain an equation for small-diameter pipes (i.e., diameter of less than 50 mm). The working voltage was varied (200, 230, and 260 kV) in order to generate appropriate X-ray energies to measure various pit depth (20, 40, and 60%, receptively) of a stepped steel pipe specimen. Film density measurements using the density and light meters showed similar results; however, the film density result using the density meter was more accurate. All tangential side edges of the specimen burned off for film densities above 3.5. Degrees of magnification (1.0123, 1.0254, and 1.0379) varied as a function of distance from the midpoint of the X-ray target (30, 60, or 90 mm, respectively). Using the results, a linear equation with three variables was obtained to determine the actual diameter of pitting: 0.000385436a + 0.038350128b + 0.000467083c = d; where the actual diameter = film diameter/d. High working voltage produced low film contrast, high film definition, and low scatter. Low working voltage produced high film contrast, low film definition, and high scatter. Based on our results, a working voltage of 260 kV is most appropriate for effective analysis.
TL;DR: In this paper, the defectoscopic properties of various compositions of powder preparations were assessed in order to determine whether they can be used as part of a modern Russian set of defectoscopic materials for luminescent penetrant testing that ensures detection of discontinuities with sensitivity class 1 as per GOST (State Standard) 18442.
Abstract: Research has been carried out to assess the defectoscopic properties of various compositions of powder preparations in order to determine whether they can be used as part of a modern Russian set of defectoscopic materials for luminescent penetrant testing that ensures detection of discontinuities with sensitivity class 1 as per GOST (State Standard) 18442. To improve the efficiency and reliability of flaw detection in hard-to-reach places of complex shaped parts, compositions have been selected that increase the brightness, contrast, and stability of the indication pattern to mechanical action due to high rates of adsorptive and adhesive interactions of the used penetrant fluid and the surface of the tested part.
TL;DR: In this paper, a LCC resonant converter based PID controller tuned with optimization algorithms for non-linear system was used to identify the local minima in time domain system, the objective functions considered are minimization of integral absolute error (IAE), integral square error (ISE), and integral time absolute error.
Abstract: X-rays are devices immensely used for diagnosis and treatment in medicinal field. X-rays are very popular as they are used in non-destructive testing. An X-ray device uses a high voltage power supply which can be produced by DC-DC converters. Resonant converters are prominent among the dc-dc converters for X-ray application as the switching is done at zero current and zero voltage. This paper presents a LCC resonant converter based PID controller tuned with optimization algorithms for non-linear system. Differential evolution optimization (DEO), grey wolf optimization (GWO) and grasshopper optimization algorithms (GOA) are used to identify the local minima in time domain system. The objective functions considered are minimization of integral absolute error (IAE), integral square error (ISE) and integral time absolute error (ITAE). The convergence curve is also plotted for the different optimization algorithms using MATLAB Simulink to study the convergence time.