Means Of Non-destructive Testing Research Articles

Using the wavelet transform to process data from experimental studies of the discontinuous plastic deformation effect

Vast number of theoretical and experimental works has been devoted to the study of discontinuous plastic deformation (the Portevin-Le Chatelier effect), which manifests itself for most widely used alloys in certain ranges of both temperatures and strain rates. Due to the statistical nature of this phenomenon, difficulties arise in processing, qualitative analysis and quantitative comparison of test results and calculations. Using of statistical methods for these purposes makes it possible to get only some averaged characteristics of the obtained data (usually - moments of the first and second orders in amplitudes and frequencies). A possible alternative for processing of experimental and theoretical results of this effect research is wavelet analysis using. The results of experimental studies of the Portevin–Le Chatelier effect, realized during the deformation of thin-walled tubular specimens made of aluminum alloy AMg6M at certain strain rates at room temperature are presented. Diagrams of deformation under uniaxial tension, shear, proportional and disproportionate loading of specimens were obtained. The inhomogeneity of strain fields and their rates is shown, illustrating the manifestation of the Portevin – Le Chatelier effect under conditions of complex loading of thin-walled tubular specimens made of AMg6M alloy. A brief overview of existing methods and means of non-destructive testing is presented that make it possible to non-contactly record the spatial heterogeneity of plastic yielding. Some possibilities of using the wavelet transform to process certain types of non-monotonic stress-strain diagrams obtained for the specimens made of the aluminum alloy in question are discussed. Using wavelet analysis, a compact presentation of data from field experiments in the form of amplitude-frequency characteristics was obtained. The scalograms analysis of specimen loading diagrams was carried out.

Ultrasonic adhesion control of special coatings

Quality control of coatings is an urgent task. Of interest is not only the detection of a defect in the coating in the form of detachment from the substrate or delamination between layers of a multilayer coating, but also the detection of the place of probable defect formation in the form of a site with reduced adhesion. The purpose of this work is to substantiate the possibility of using the reflected radiation method (echo method) of an acoustic type of non-destructive testing with optical-acoustic generation of acoustic vibrations to assess the adhesion between the coating layers and between the coating and the substrate. The objective of this work is to establish a correlation between the acoustic characteristics of coatings and the tear strength of coatings. The relevance of the work is emphasized by the lack of methods and means of non-destructive testing of adhesion of coatings with proven effectiveness and reliability to date. In order to achieve this goal, coating samples with embedded artificial defects were developed and manufactured. A correlation was established between the acoustic characteristics of the coating and the tear-off strength of the coating, confirmed as a result of mechanical tests, which emphasizes the scientific novelty of the research.

METHOD OF ULTRASONIC PHASE TWO-COORDINATE INFORMATION REGISTRATION FOR AUTOMATED NON-DESTRUCTIVE TESTING SYSTEMS

The article is devoted to the issue of improving the coordinate registration of information in means of automated non-destructive testing. Existing systems of non-contact registration of spatial position sensors of non-destructive testing are mostly focused on the use of signal fields of different physical nature, for example, acoustic or optical, which are created around the position of these sensors and amplitude methods of signal processing. These methods do not provide the necessary accuracy of determining the coordinates in the case of using small-aperture sensors of non-destructive testing.
 The basis of the proposed technical solution is the trilateration method. The distance between the emitter of ultrasonic vibration, which is structurally connected to the sensor, and the two receivers is determined by the phase method. This method provides increased accuracy in determining the coordinates of the sensor. Eliminating the ambiguity of phase measurements is based on the combination of the multi-frequency method and the numerical system of residual classes. This makes it possible to minimize the probability of incorrect resolution of the ambiguity of the results of phase distance measurements and to ensure high accuracy of coordinate determination (with an absolute error of the order of mm). The idea of the method and the main calculation formulas that make it possible to determine the modules of the numerical system of residual classes and the values of the operating frequencies of ultrasonic oscillations are presented. Matching the discretes for determining the phase shifts of signals with the modules of the numerical system of residual classes at different operating frequencies makes it possible to reduce the resolution of the ambiguity of the results of phase measurements to the task of restoring integers in the positional counting system from their representation by residuals in the numerical system of residual classes. The mechanism of occurrence of gross errors in the recovery of whole numbers is considered. An algorithm for eliminating this error is proposed. In general, the correctness of the algorithm for determining the sensor coordinates is confirmed by the simulation results. The considered method of two-coordinate information registration can be used both in the development of new automated means of non-destructive testing, and for the improvement of existing ones, which involve a manual method of scanning the surface of testing objects.

An Overview of Vibration Analysis Techniques for the Fault Diagnostics of Rolling Bearings in Machinery

The perfection of methods and means of nondestructive testing and technical diagnostics is determined by the level of development of science and modern industrial technologies. The desire to develop technologies determines the extent and degree to which the monitoring of the state of substances, materials, products—and now the state of the natural environment—are becoming increasingly relevant. The methods and means of condition monitoring and the diagnostics of rolling bearings have been in development for more than 60 years. Despite some successes, however, there is currently no information concerning the veracity of means to completely resolve the bearing diagnostics problem. This paper provides a fairly brief overview of methods and means for monitoring the condition and diagnosis of rolling bearings and also describes one of the newest trends in this field—the analysis of the properties of the characteristic function of vibroacoustic (VA) signals in order to determine the condition of the objects of control and, in particular, rolling bearings. It is shown that the magnitude of the module and the area of the characteristic function of the VA signal are very effective criteria for assessing the technical condition of a rolling bearing.

GREEN ENERGY AND NON-DESTRUCTIVE TESTING

The article summarizes the results of the companies' achievements at the exhibition "RENWEX – 2022". Like any products, green energy products are subjected to tests and diagnostics to confirm their quality and reliability. The main methods and means of non-destructive testing and examples of their practical use in improving the quality of green energy products are given.

Detection of Cut Notches and Corrosion on Anchor Bolts

The overhead catenary system (OCS) comprises of the pantograph which presses against the underside of the lowest overhead wire or the contact wire. Current collectors are electrically conductive and allow current to flow through to the train and back to the feeder station through the steel wheels on one or both running rails. With water seepage due to occurrence of monsoon rain and porosity of the cement material, the mineral rich rock structure can undergo much more rapid degradation under an electrochemical process due to the potential of the OCS. SEM images of the corroded bolts segment show high porosity surface with corroded voids. EDX study shows the presence of high oxide, chloride, and iron elements as indicative of a corroded bolt. The first backwall echo of the ultrasonic peak amplitude provides an understanding of the length of a bolt. Comparative study can provide a signature of the bolts which have been corroded with less fringe peaks due to the presence of bolts’ threads which tends to wear out with the duration of corrosion. Fatigue cracks are mimicked and modelled with cut notches of varying depths on bolts followed by immersion in corrosive peroxide solution for accelerated corrosion. A good clear distinction of the presence of such peak signal amplitudes due to cut notches with the referenced backwall echo peaks of the corroded bolts could be registered by the ultrasonic tests. The height of the signal peak amplitudes could give an indication of the depth of cut at the notch and the quantity of such peaks provide an indication of the number of cut notches. The ultrasonic test provides an effective means for non-destructive testing of such bolts which are embedded in concretized underground tunnel.

Determination of Dynamic Range of Stand-alone Shock Recorders

Abstract In aircraft construction, when creating samples of new equipment, shock tests are often performed, both on individual components and the entire product. It requires introducing non-destructive testing devices into production, it is one of the most important factors in accelerating scientific and technological progress, raising the quality and competitiveness of manufactured products. Applying modern means of non-destructive testing, there is the problem of their protection from external vibrations, which affect the sensitivity, accuracy and reliability of high-precision measurements. In such cases, the conversion of measuring information during powerful vibration and shock tests, as a rule, is carried out by piezoelectric acceleration sensors. Although to provide impact testing, there is a need to develop and use stand-alone recorders. The main requirements for these recorders are to ensure the autonomy and operability of the recorder onboard the test product and to ensure the synchronization of the registration of the shock load.

POSSIBILITY OF IDENTIFYING DEFECTS IN MASSIVE CAST STRUCTURES BY NON-DESTRUCTIVE TESTING METHODS

In the context of improving methods and means of non-destructive testing (NDT), along with increasing in formativeness, complex technical problems arise. For example, when examining structural elements with a service life of more than 20 – 30 years, modern NC tools detect defects that have not been rejected by the manufacturer. Assessment of the impact of such defects on the operability of the structure requires a comprehensive study using NC and strain gauge. The purpose of the work is to evaluate the parameters of defects in a cast part of a hydraulic stamping press with a service life of more than 60 years in order to make a decision on the possibility of its further operation. The defect was investigated using magnetic powder, eddy current and ultrasonic control methods. By means of strain gauges, mechanical stresses are measured directly during operation. The indicator pattern of the magnetic particle inspection defect has signs uncharacteristic for fatigue defects: branching, intermittent and broken (not smooth) character. To quantify the degree of smoothness of the indicator pattern, it is proposed to use a fractal dimension, which for the defect under study was 1.07. The estimated depth of the defect detected by the eddy current method was from 4 to 6 mm, by ultrasound – from 8 to 18 mm. The presence of an echo signal by a direct converter indicates the volumetric nature of the defect. After mechanical removal of the surface layer with a thickness of 2 mm in some areas, the width of the defect increased to 2 mm, and the depth to – 20 mm. On the inner side surface of the defect, a dense, dark scale characteristic of high temperatures is visually determined.The defect is classified as a casting shell with a depth of 20 mm. No traces of fatigue failure were found. Compressive mechanical stresses with an amplitude of no more than 41 MPa amounted to less than 20 % of the fatigue endurance limit of 35L steel. During the year, the average number of working cycles is 20 thousand, repeated examination of the press defect is recommended in 5 – 10 years (100 – 200 thousand cycles).

QUALITY AS AN ELEMENT OF THE SHIP REPAIR ENTERPRISE MANAGEMENT SYSTEM

The situation in the ship repair industry taking into account the organization of production, quality management and quality control during the ships repair is analyzed. The necessity of improving the technological processes of ship repair production is proved. It is proposed to continuously improve the production process by reducing losses arising from irrational production management. The introduction of lean manufacturing principles will significantly reduce losses. It is pointed out that it is necessary to solve the problems of providing ship repair production with modern means of non-destructive testing and complexes of new devices in order to improve the processes of quality control of ship repair work, since the improvement of means and methods of control contributes to improving the efficiency and quality of ship repair work. Conclusions that the high quality of repair work is ensured by the exact compliance with the established technology and careful consistent control, starting from the original materials and ending with the testing of finished products are drawn. The lack of preventive control functions, and therefore an active impact on quality, is the main drawback of the existing control system. It is indicated that there are such negative indicators as insufficient depth of theoretical justifications and the sequence of taking control actions, non-compliance with the basic principles of building control systems (centralization and independence of control, quantitative quality measurement, factor-causal analysis), lack of a comprehensive nature of measures and a systematic approach. In the future, it is proposed to create a quality management system that could prevent defects, and preventive control functions would allow systematically improving the quality of ship repair work.

Finding the Dynamic Range of Recorders During Impact Tests

In aircraft construction, when creating samples of new equipment, impact tests are often performed, both of individual components and of the entire product. It requires to introduce non-destructive testing devices into production, it is one of the most important factors in accelerating scientific and technological progress, raising the quality and competitiveness of manufactured products. Applying modern means of non-destructive testing, there is the problem of their protection from external vibrations, which affect the sensitivity, accuracy and reliability of high-precision measurements. In such cases the conversion of measuring information during powerful vibration and impact tests, as a rule, is carried out by piezoelectric acceleration sensors. Although to provide impact testing, there is a need to develop and use stand-alone recorders. The main requirements for these recorders are to ensure the autonomy and operability of the recorder on board the test product and to ensure the synchronization of the registration of the impact load.

Application of magneto-optical method for detection of material structure changes

The possibilities of magneto-optical sensors to control the damage of ferromagnetic and para-magnetic materials and products are considered. In the introduction it is shown that modern magneto-optical materials used in creating sensors have a high sensitivity and spatial resolution. So, on their basis it is possible to develop sensitive and informative means of non-destructive testing for a wide range of applications. For example, it is used to detect microcracks, corrosion damage, degradation changes in the material structure, surface deformations, and subsurface defects. The method ability to detect appearance of magnetic phases in paramagnetic materials, that are precursors of fracture, is of a special importance. The advantage of magneto-optic sensors is a large observation area and high spatial resolution. Resolution of the sensor is determined by the period and size of the domain structure, which averages 13...50 micrometres. High sensitivity of the sensor is due to a small saturation field of the magneto-optic material from 0.1 mT to 0.7 mT. In addition, these parameters are controlled by changing the temperature of the sensor, direction and intensity of the magnetic field. In this paper an optical scheme based on magneto-optical garnet film for visualization of fatigue cracks, which are formed in compact samples during their experimental investigation on fatigue failure is described. The developed scheme allowed us to visualize and fix position of the crack and determine its actual length, considering the closed part of the crack. A further direction of research will be to increase the sensitivity of the developed scheme and reduce the noise of magneto-optical images to identify the initial stages of the degradation process of ferromagnetic and paramagnetic materials and products.

METHODS OF CONDITION MONITORING AND DIAGNOSTICS OF ROLLING BEARINGS OF CENTRIFUGAL MACHINES AND MECHANISMS

The perfection of methods and means of non-destructive testing and technical diagnostics is determined by the level of development of science and modern industrial technologies. The desire to develop technologies determines the growing needs for monitoring the state of substances, materials, products, and now the control of the state of the natural environment is becoming more and more relevant. Methods and means of condition monitoring and diagnostics of rolling bearings have been developed and developed for more than 60 years. Despite certain successes, today there is no information about the veracity of ways to solve this problem. The paper provides a fairly brief overview of methods and methods for monitoring the condition and diagnosis of rolling bearings, and also describes one of the newest trends in this field – the analysis of the properties of the characteristic function of vibroacoustic signals in order to determine the condition of the objects of control and, in particular, rolling bearings. It is shown that the magnitude of the module and the area of the characteristic function of the vibroacoustic signal are very effective criteria for assessing the technical condition of a rolling bearing.

A review on nondestructive testing of bonding interface using nonlinear ultrasonic technique

<p indent="0mm">As an important complement to traditional mechanical connections, bonded structures are widely used in industry. Under the combined effect of external loads and environmental factors, the performance of the bonding interface will deteriorate, which seriously affects the safe use of bonding structures. Therefore, the performance evaluation of bonding interfaces has always been a hot and difficult issue in the field of non-destructive testing. Traditional linear ultrasonic technology can effectively detect damage such as delamination and debonding in the bonding interface, but it is difficult to detect and quantitatively evaluate the early degradation of the bonding interface (such as closed defects and weak bonding). However, the nonlinear ultrasonic technology can overcome the low sensitivity of the traditional linear ultrasonic technology and is expected to be an effective means for nondestructive testing of early deterioration of bonding interface performance. In this paper, we review the recent development of nonlinear ultrasonic technology for bonding interface detection from theoretical models and testing experiments. From the perspectives of contact nonlinearity of the interface and material nonlinearity of the interlayer, we introduce relevant theoretical models for nonlinear ultrasonic inspection of bonded interfaces, such as nonlinear spring model, interface contact model and contact model considering the thickness of the interlayer. These models can be used for the description of various acoustic nonlinear effects (such as second harmonic generation, wave mixing and nonlinear resonance) generated by ultrasonic waves at weak bonding interfaces, but the ability of different models to characterize the nonlinear propagation behavior of ultrasonic waves at weak bonding interfaces needs to be further investigated. Meanwhile, we review the progress of three nonlinear techniques of nonlinear ultrasonic resonance, wave mixing and second harmonic generation in the experimental testing of bonding interface properties. The nondestructive testing of bonding interface using nonlinear ultrasonic resonance technique remains relatively limited. Mixing technology is of great interest because of its flexibility and selectability of excitation frequency, mode and area of action, and its ability to effectively avoid the effects of system nonlinearity. Among the nonlinear ultrasonic methods, harmonic techniques are the most widely used, and have been used for damage detection and performance evaluation of bonding interfaces, such as bonding thickness measurement, debonding detection, bond strength and fatigue life evaluation. The harmonic technique is considered as a possible solution for the quantitative detection of the interface properties of multilayer bonded structures. However, how to distinguish the harmonics generated by weakly bonded interfaces from those generated by detection systems has been a challenge for its application. Finally, we provide an outlook for the development of nonlinear ultrasonic detection technology for early degradation of bonding interfaces.

Nonlinear error correction for Terahertz FMCW System by a new beat frequency estimation method.

Terahertz (THz) frequency modulated continuous wave (FMCW) technology is a means of nondestructive testing. The signal's nonlinearity is an unavoidable problem in the daily application of THz FMCW technology. The signal's nonlinearity will lead to the spectrum broadening of the FMCW's beat frequency (BF) signal, which degrades the range resolution and result in distance-measuring error. Traditional methods require additional hardware or require a lot of computation, which are not conducive to the miniaturization of the system and real-time measurement. A novel method for correcting the nonlinear error of THz FMCW technology has been proposed and demonstrated in this article. In the proposed method, the windowed Fourier transform (WFT) is introduced to estimate the BF corresponding to the measured target, according to the linearity distribution of voltage-controlled oscillator (VCO). In this way, the measured target's BF can be accurately estimated from the unprocessed BF signal with a poor linearity. From the estimated BF of the reference target, the non-linear compensation coefficients are calculated. With the non-linear compensation coefficients, the non-linearity of the output BF signal can be calibrated. The results of simulations and experiments show that the proposed method allows the range resolution of an FMCW system to reach the theoretical limit.

Preliminary evaluation of a density-based lumber grading method for hem-fir CLT manufacturing

In the manufacturing process of cross-laminated timber (CLT), lumber selection and grading are essential steps for the quality control of CLT. In this work, a density-based lumber grading method was preliminarily evaluated for hem-fir CLT manufacturing. Based on the univariate regression model of hem-fir lumber modulus of elasticity (MOE) and its density, a density-based grading model was developed. To identify the effectiveness of the model, 470 pieces of thin hem-fir lumber, were segregated into four grades: E1, E2, E3, and E4 based on their density values. Two 3-ply thin-type customized CLT panels were also fabricated with E2 grade lumber as the parallel layer and E3 grade lumber as the transverse layer. Then, five CLT beam specimens were cut from each panel for flatwise bending test. Comparing the experimental and the theoretical values of the MOE, the relative errors were found to be + 11.95% (using shear analogy theory) and − 7.21% (using gamma theory), respectively. By comparison, for this hem-fir lumber, the accuracy of this density-based grading method is close to that obtained by other means of non-destructive testing. However, it seems to be simpler and more cost-effective for the potential hem-fir CLT manufacturing in some circumstances.

Information Support Methods and Algorithms for Non-destructive Control System Management

The article considers the possibility of using software in conjunction with statistical methods of analysis for continuous monitoring of the activities of non-destructive testing divisions and assessing their condition and effectiveness. Using the developed software allows increasing the efficiency of management and decision-making on the elimination of discrepancies in the structural units of the car repair complex. An assessment of the level of risk associated with the technical condition of non-destructive testing means was carried out. Based on the results of the analysis of normative and technical documentation for the organization of the non-destructive testing process, a system of criteria has been developed that describes the state of equipment with control means. Units having inconsistencies with the requirements for the minimum required amount of equipment and control means were identified. Statistical data on the results of rejection of the brake shoe suspension and the pendulum suspension of freight cars in the structural units of the car repair complex are examined in detail. The kind and numerical characteristics of statistical models of data distribution for each type of part are determined. Structural units were found that significantly exceeded the average frequency of rejection. It is shown that the use of software and statistical analysis methods can improve the efficiency of non-destructive testing units in structural unit management of the car repair complex.

Nondestructive detection of yellow peach quality parameters based on 3D-CNN and hyperspectral images

In recent years, efficient and accurate detection of fruit quality has become an important means of non-destructive testing of fruit quality. In order to solve the problems of cost, efficiency and accuracy in the non-destructive testing of yellow peach quality. This paper proposes a new method for simultaneous detection of yellow peach hyperspectral multiple quality parameters. This method uses the method of extracting and recombining wavelengths at equal intervals in the full-band spectrum instead of the characteristic wavelength selection method. It can make the hyperspectral image contain all-band spectral information. This method uses 3D-CNN to replace the original regression modelling method, which improves the accuracy of model prediction. This method uses the shared network convolutional layer method to perform multi-task learning on the sugar content and hardness of yellow peaches, and finally realizes the simultaneous detection of multiple quality parameters of yellow peaches.

MONITORING BY FIBER OPTICAL SENSORS OF RELIABILITY OF OPERATION OF BUILDING STRUCTURES WITH EXTERNAL COMPOSITE REINFORCEMENT

This article describes of the actual state of building structures by the example of structures of reinforced concrete and metal bridges. It is shown that a high degree of wear of artificial structures leads to the need for a reliable assessment of their actual condition using modern methods and means of non-destructive testing and diagnostics, as well as strengthening exploited structures with polymer composite materials. The results of researches on fiber-optic monitoring and strengthening of bridge spans with composite materials based on domestic and foreign carbon reinforcing fillers and epoxy polymer matrices are presented. It has been experimentally shown that for reinforced concrete structures it is advisable to use composite strengthening systems using external reinforcement installed directly on the damaged object by contact molding. For metal structures, this approach is not applicable due to a significant difference in the coefficients of linear thermal expansion of composites and metals. In this case, an amplification system based on prefabricated composite truss systems made by autoclave and unautoclave molding can be applied. The obtained research results also indicate the advisability of joint use of monitoring systems and strengthening of damaged bridge structures by composites.

Search for defects and assessment of the current condition of engineering structures with the help of georadars (review. Part II)

The relevance. The development of technical means for non-destructive testing and remote sensing is an important practical task. This is primarily due to the fact that modern means of non-destructive testing open up ample opportunities for the introduction of new technologies and increase the economic efficiency of measures for the maintenance of various technical and construction objects at a relatively low cost of such work. In this regard, the development of computational algorithms for processing primary data and software products for the subsequent interpretation of the results obtained using computer engineering systems is of great importance. The purpose of the work is to review technical means, signal processing methods and some computer-oriented engineering systems for solving problems of detecting various defects in engineering structures and building structures. Materials and methods. The paper provides a brief overview of methods for processing primary data sets obtained using pulsed GPR. At the next stage, processing is carried out using the GeoVizy program. Finally, the main focus of the work is on the analysis of the capabilities of modern computer engineering tools. Also used the numerical - analytical methods of the modern theory of diffraction and methods of signal analysis in the space-time domain. Results. The results are based not only on scientific articles, but also on the analysis of the capabilities of modern computer modeling systems, as well as some mathematical models obtained by the author. Conclusions. The results presented in the article allow one to talk about a new direction in scientific research. This direction can be defined as combined multi-parametric analysis - CoMPA. The purpose of this direction is to conduct research of various interrelated processes in technical structures by using the methods of mathematical physics, combining not only the analysis of their interaction with fields of different physical nature, but also involving the appropriate models from various areas of mathematical physics. The significance of the results obtained consists not only of new models of data processing and interpretation, but also of the prospects for further progress in the field of technical means of control and diagnostics.

TEM apparent resistivity imaging for grounding grid detection using artificial neural network

Transient electromagnetic (TEM) method is a reliable means of non-destructive testing for fault diagnosis of grounding grid in substation. In view of the small transmitter loop of the TEM system and many measuring points and survey lines of grounding grid detection in substation. This study presents a fast solution to TEM apparent resistivity imaging for grounding grid detection using artificial neural networks. The input -output mapping relation of neural network is established based on TEM response characteristics of the grounding grid. The built network could map the recorded TEM data of grounding grid detection and quickly obtain the resistivity image. The proposed method offers accuracy and fast computation for the resistivity imaging of grounding grid. Feasibility and technical attractiveness of the proposed method in fast imaging of apparent resistivity is investigated with the measurement of grounding grids in the actual substations. It can be used in real time so that the recorded TEM data in substation can be calculated without re-training, which avoids time-consuming inversion computation. The rapid processing of massive data and submitting the detection results of the grounding grid to customers rapidly and in real time, which is expectation for a modern power industry.