Thermal Nondestructive Testing Research Articles

ОПРЕДЕЛЕНИЕ ПОПЕРЕЧНЫХ РАЗМЕРОВ ДЕФЕКТОВ РАССЛОЕНИЯ БИМЕТАЛЛИЧЕСКОЙ ПЛАСТИНЫ ПРИ АКТИВНОМ ТЕПЛОВОМ НЕРАЗРУШАЮЩЕМ КОНТРОЛЕ

Various methods of nondestructive testing, including active infrared thermography, are used to detect latent subsurface defects in the contact of layers in multilayer products. One of the main difficulties using this method consists in processing and interpreting the thermal image data. The peculiarity of investigated defects of bimetal plate layers continuity violation is that the depth of defect location is known and the main task is to determine its size. Some methods are used for this purpose including analysis of spatial temperature profiles. Aim. To analyse the use of various approaches to determining the transverse dimensions of a delamination between metals in simulating active thermal non-destructive testing of steel-aluminium plates. Materials and methods. Mathematical and computer simulating methods, numerical differentiation are used. The delamination size is determined by projections of half the height of the amplitude signal and the extremum of the derivative of the temperature signal function. Calculations and graphical constructions are performed using the mathematical package GNU Octave. Results. Numerical simulation is carried out for different values of heat flow power, heating and cooling time. The temperature signal distribution over the surface of a multilayer bimetallic plate has been plotted. The values of the defect radius according to the projections of the characteristic points are determined. Conclusion. The results of simulation allow us to conclude that using the projection of the extremum of the temperature signal derivative function allows us to accurately estimate the defect size, while in the case of the point projection cor¬responding to half of the signal amplitude height, the result is underestimated. The obtained results can be used for further experimental studies of processes of active thermal non-destructive testing of products made of multilayer bimetallic materials.

Machine learning based models for defect detection in composites inspected by Barker coded thermography: A qualitative analysis

Machine learning and artificial intelligence have evolved as enablers for automation in various industrial applications. Barker-coded thermography is an active thermal non-destructive testing technique for examining subsurface features in industrial components. This article introduces supervised and unsupervised machine learning models for automatic defect detection in composite specimens inspected by the barker-coded stimulus. This work provides supervised and unsupervised machine learning methods to detect defects in composite specimens examined with a barker automatically coded stimulus. The suggested technology is tested using a carbon fiber-reinforced polymer sample with synthetically reproduced flat bottom hole flaws. The one-class Support vector machine is chosen for the unsupervised class of operation, whereas the supervised technique modifies the traditional Support Vector Machine (SVM). The qualitative comparison suggests that the unsupervised approach presents a less than 1% marginal difference in defect detection from its supervised counterpart.

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ДЕЯТЕЛЬНОСТИ ПРОМЫШЛЕННЫХ ПРЕДПРИЯТИЙ, СВЯЗАННЫХ С ПРОИЗВОДСТВОМ И ИСПОЛЬЗОВАНИЕМ БИМЕТАЛЛИЧЕСКИХ ЛИСТОВЫХ МАТЕРИАЛОВ

Improving the efficiency of industrial enterprises is heavily reliant on the technologies employed in production and the practical application of the products and structures produced by the companies. The authors' research on quality control methods for manufacturing bimetallic sheet materials and technological equipment has revealed that non-destructive testing methods can significantly reduce production costs. The study identifies thermal testing as one of the most effective forms of non-destructive testing. Aim. The research aims to explore these testing methods and their cost-saving benefits within current technological procedures. Justifying the use of thermal non-destructive testing as a method for improving the quality control of bimetallic sheet materials during the manufacturing process and enhancing the efficiency of management in industrial enterprises of the relevant profile. Materials and methods. Analysis of researches in the field of technologies and methods of thermal non-destructive testing for enterprises. Results. The benefits and cost-effectiveness of using thermal non-destructive testing methods in manufacturing companies that produce products and use technological equipment with bimetallic sheet materials are demonstrated. Requirements are outlined and a quality control system structure for these materials is established based on the thermal non-destructive testing method. A mathematical model for determining the thermal state of a bimetallic plate is presented alongside the potential for its software implementation. Conclusion. The method of thermal nondestructive testing proves to be efficient and productive in modern conditions, enabling acceptable cost implementation of quality control systems in production and operation. The findings can be applied in industrial companies that work with multilayer bimetallic materials in their products and constructions.

Linear frequency modulation infrared thermal imaging detection technology for GFRP/PMI foam sandwich structure defects

As one of the important structures of composite materials, polymethacrylimide (PMI) foam sandwich structure is prone to debonding and delamination defects during manufacturing and service, which seriously affects the mechanical properties of materials. Therefore, it is necessary to detect the defects of foam sandwich structure. A linear frequency modulation infrared thermal wave nondestructive testing system was built to study the correlation between the geometric characteristics (diameter and depth) of the defect and the surface temperature signal and its influence on the detection effect. The image sequence is processed by principal component analysis, discrete Fourier transform, thermal wave signal reconstruction, and other algorithms. Studies have shown that the larger the defect diameter, the shallower the depth, easy to detect defects, detection effect is good. The detection system can effectively detect and identify debonding and de-lamination defects. The thermal wave signal reconstruction method is superior to the principal component analysis method and the discrete Fourier transform method in the signal-to-noise ratio index, which improves the quality of the image and is conducive to the effective identification of the image surface defect information.

МЕТОД ИНФРАКРАСНОЙ ТЕРМОГРАФИИ ДЛЯ ВЫЯВЛЕНИЯ ПОВРЕЖДЕНИЙ НА КОМПОЗИЦИОННЫХ МАТЕРИАЛАХ ПРИ УДАРНЫХ ВОЗДЕЙСТВИЯХ С МАЛОЙ ЭНЕРГИЕЙ

The use of thermal non-destructive testing of products made of polymer composite materials for impact damage is one of the promising directions. The paper presents a mobile monitoring approach that provides damage detection at low impact values. A feature of the developed method of impact damage detection is a comprehensive consideration of the presence of a coating on the surface of composite material, the type of a source of thermal loading, the technical excellence of the thermal imager and the capabilities of the temperature imaging software. In the post-processing of thermal imaging data, the method used monoframe-processing technology, which included a set of operations: visualization of imaging data in a monotone palette, contrast enhancement of the thermal image and sub-framing – narrowing the area of analysis of the original thermal image, with a scanning search.

The Quality Assessment of External Building Envelopes Using Thermal Non-Destructive Testing of Residential Buildings

The Quality Assessment of External Building Envelopes Using Thermal Non-Destructive Testing of Residential Buildings

Reducing the level of interference at thermal non-destructive testing considering the specific thermal physical and morphological characteristics of the object

The Paton Welding Journal, 2022, №12. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

Thermal Nondestructive Testing of Composite and Metal Parts Manufactured by Additive Technologies

Thermal Nondestructive Testing of Composite and Metal Parts Manufactured by Additive Technologies

Infrared thermographic analysis of thermal property variations in composites subjected to impact damage, thermal cycling and moisture saturation

The new results on the relationships between impact damage energy and thermal property variations in carbon and glass fiber reinforced plastics have been obtained on “dry” composite samples, as well as on the samples subjected to thermal cycling and moisture saturation. The estimates of impact damage detection limit are presented, and the impact energy ranges where variations of effusivity and diffusivity linearly depend on energy are obtained. The experiments on the samples subjected to long-term moisture saturation and thermal cycling revealed no significant influence of these impacts on thermal property. It is concluded that thermal nondestructive testing may serve as a reliable tool for estimating severity of impact damage in aircraft composite structures.

Practical limits of pulsed thermal NDT: The concept of additive/multiplicative noise

The approach to determining thermal nondestructive testing (TNDT) limits by defect parameters is presented on the base of the suggested concept of noise. The concept presumes that active TNDT limits are conditioned by the inherent noise, which can be conventionally classified for additive and multiplicative. It is shown that practical TNDT limits are associated with multiplicative noise, which can be conveniently expressed in terms of noise running contrast. Considering a certain interval of running contrast values adhered to a particular construction material can be useful when determining potentials of thermal NDT by minimal size and maximal depth of detected defects, for example, by using a simple analytical 1D model.

3D modeling of pulsed thermal NDT: Back to basic features and subtle phenomena

By using advanced 3D modeling of thermal nondestructive testing (TNDT) problems, most of basic TNDT features are shortly described, but the emphasis is put on the analysis of some subtle physical phenomena which may be observed in TNDT experiments, and most of them have not been properly reflected in the earlier studies. These are: 1) the “smashing” of 2D defect surface “footprints” because of 3D heat diffusion, 2) practical approaches to determining defect lateral size by their surface temperature indications, 3) clarification of a limiting defect size/depth ratio providing reliable detection of subsurface defects; 4) inversion of “classical” temperature signals at longer times, 5) defect shading, 6) influence of composite anisotropy on defect detectability, and 7) combined heating/cooling allowing to govern behavior of surface temperature profiles.

Characterising Hidden Defects in GFRP/CFRP Composites by using Laser Vibrometry and Active IR Thermography

ABSTRACT This paper describes the use of laser vibrometry and thermal non-destructive testing for detecting defects in GFRP composite by applying a single test procedure. The laser vibrometry involves the averaging of vibration amplitudes over an entire frequency spectrum accompanied by the frequency-phase analysis. Such procedure may lead to suppression of low signals, produced by smaller and deeper defects, by higher signals conditioned by larger and shallower defects. The fusion of results obtained with both laser vibrometry and thermal NDT was used to enhance defect detectability. The corresponding experimental techniques were applied to detecting four types of defects (air gaps, foam, blank grooves, resin) in GFRP composite, as well as evaluating defect size and depth. Also, laser vibrometry was used to characterise barely visible impact damage in CFRP composite, and test data was compared with C-scan ultrasonic inspection results. It has been shown that the results supplied by three inspection techniques have been reasonably consistent in characterisation of defect lateral area and depth. When analysing the complex structure of impact damage in composites, the detection of both shallow and deep defects can also be enhanced by performing fusion of test results supplied by laser vibrometry and active thermal NDT.

Возможности использования математических моделей для теплового контроля дефектов многослойных биметаллических пластин

There is an actual task of delamination detection in multilayer bimetallic materials. Various methods of nondestructive testing (NDT) are used to solve it, including the method of transient thermal NDT. This method consists in remote registration, visualization and analysis of thermal (temperature) fields, which depend on thermophysical and geometric characteristics, thermal effect capacity and internal structure features of the object. The internal structure defects cause the appearance of abnormal temperature zones on the object surface. Their analysis allows us to judge the presence of changes in the material as a whole or in individual areas. It is possible to understand whether there is a defect under the anomalous site, and what its parameters are, if there is an adequate mathematical model that theoretically describes the dependence of the measuring results on the properties of the object and the selected technological modes. This model is a significant component of thermal NDT systems. For the same object or process, a certain set of mathematical models can be compiled, differing in the number of factors taken into account, the assumptions made, the completeness and accuracy of the description of the state of the object or the conditions of the process. The set of factors is determined by the purpose of the study, and in order to unambiguously determine the model of the thermal state, it is necessary to describe the characteristics of the object (geometric shape and thermophysical characteristics of the material) and the heat exchange process (characteristics of heat sources, initial and boundary conditions). Aim. To analyze the existing mathematical models for the research object – a multilayer bimetallic plate with delaminations between the outer and inner layers, and to identify common approaches to modeling the processes of thermal NDT of multilayer objects. Materials and methods. The structure of the mathematical model of the thermal state of the object is determined. An analytical review of mathematical models of thermal NDT of multilayer objects is performed. Results. The requirements, assumptions and limitations for a mathematical model of thermal NDT of a multilayer bimetallic plate with delamination defects are formulated. Conclusion. On the basis of the considered approaches to the mathematical modeling of the thermal state of multilayer objects with ideal layers contact and delamination defects, the necessary factors for the development of a model for the transient thermal NDT processes of the studied objects are determined.

Моделирование нестационарной теплопередачи в многослойной биметаллической пластине

When using the method of active thermal non-destructive testing to detect latent defects in multilayer bimetallic products, the adequate choice of technological modes of testing is of great importance. One of the important parameters is the optimum observation time, at which a sufficient amplitude of the temperature signal over the defect is provided. This value depends on the controlled object geometry, its thermophysical characteristics, and also selected testing modes and procedures. Various experimental stu-dies are used to determine the optimum observation time. Preparing bimetallic plates samples for full-scale experiments is a technologically complex and expensive task. Therefore, a large amount of preparatory research is carried out in the form of a numerical experiment, during which, with certain assumptions, changing the thermal state of the control object is simulated. Aim. Determination of optimal parameters of the thermal NDT process for a three-layer steel-aluminum plate with a planar delamination defect between the metal layers. For different variants of mutual location of the temperature registration device and source of heat flux of different power it is necessary to determine the heating time at which the sufficient amplitude of temperature signal is observed. Materials and methods. The methods of mathematical and computer modeling were used. Solving the task by the finite element method with the Agros2D code is given. Results. The calculation data have been obtained, which are used as the basis for constructing the temperature signal distribution over the bimetallic plate surface above the defect under different heating modes, heat flux rate, relative position of the heat stimulation source and temperature registration device, as well as determining the temperature signal dependence over the defect on the heating time. Conclusion. On the basis of modeling the temperature dependences necessary for interpretation of the results of thermal NDT of multilayered bimetallic plates have been determined, as well as the relations between the parameters of the heating process, which contribute to obtaining a temperature signal of sufficient amplitude. The results can be used for further experimental studies of the active thermal NDT processes of multilayer bimetallic materials.

Simulated thermal image based on finite element models for a layered composite structures

This research aims to develop a simulation technique to predict the experimental results of the transient Thermal Nondestructive Test (TNDT) on Carbon fiber-reinforced polymer (CFRP) materials that have defects in them. This simulation uses finite element method-based software to solve the temperature distribution on the material surface. Such an approach is not only flexible but also essential to the successful implementation of TNDT procedures. The developed CFRP material model is made up of multiple layers with several depths of defects. The defects are represented by the material-inserted isosceles triangle and the voids isosceles triangle. Heat is applied to the model front surface for some time and then released and the model cools down naturally. The temperature distributions of the model's surface are measured during the heating and cooling process. The simulation results show that simulation can detect the existing defects, their location, and their relative depth. The thermography experiment was carried out to verify the simulation results. The experimental results were analyzed using the local differential temperature signal parameter. This simulation will streamline the desired experimental design.

The Quality Assessment of Exterior Building Fences Using Thermal Non-destructive Testing of the Building of the Heat Supply Enterprise

The Quality Assessment of Exterior Building Fences Using Thermal Non-destructive Testing of the Building of the Heat Supply Enterprise

The Quality Assessment of Exterior Building Fences with Using Thermal Non-Destructive Testing of a Public Building

The Quality Assessment of Exterior Building Fences with Using Thermal Non-Destructive Testing of a Public Building

Исследование поверхностного окисления циркония активным тепловым методом

The possibility of testing the surface oxidation of zirconium has been investigated by the method of one-way active thermal non-destructive testing based on the analysis of radiation temperatures. The emissivity of the oxidized surface of zirconium samples obtained at different annealing temperatures was estimated at various stages and heating temperatures in the infrared wavelength range. It is shown that there is a principal possibility to remotely test the oxidation process of zirconium alloys used in the nuclear industry for the manufacture of fuel elements operating in the core of nuclear reactors.

Experimental and Numerical Analysis of Multiple Low-Velocity Impact Damages in a Glass Fibered Composite Structure.

Glass fiber-reinforced polymer structures (GFRPS) are widely used in civil and mechanical fields due to their light weight and corrosion resistance. However, these structures are prone to damage with very-low-energy impacts. The reliability of such structures is of prime importance before their installation and usage. This study aimed to identify, visualize, localize, and verify multiple barely visible impact damage (BVID) in a GFRPS using a combination of guided waves (GW)-based online structural health monitoring (SHM) and thermal strain-based nondestructive testing (NDT) approaches. Global NDT techniques like the use of a laser Doppler vibrometer (LDV) and digital image correlation (DIC) were used in the experimental analysis. The effectiveness of the experimental LDV-GW process was also checked numerically with the spectral element method (SEM). A threshold-based baseline free SHM approach to effectively localize the damages was proposed along with quick DIC verification of composite structure with thermal loading based on short-pulse heating as an excitation source. This study analyzed combined experimental- and numerical-based SHM-NDT methods in characterizing the multiple BVIDs located in a GFRPS.

Определение параметров дефекта расслоения биметаллической пластины посредством активного теплового неразрушающего контроля

Bimetals are in many ways substitutes for scarce metals, while they represent an independent group of materials necessary for the creation of new machines, devices and other various products. The increasing volume of production of bimetals and products made from them requires an increase in their operational characteristics and, accordingly, an increase in the quality of finished products. One of the difficult technological tasks is the connection of aluminum and its alloys with steels of various classes, since there are many problems associated with the quality of the connection of me¬tals with different properties. To improve the reliability and durability of machines and other pro¬ducts made of bimetals, it is necessary to carry out continuous quality control, and the most effective methods are non-destructive testing. Quite promising in terms of simplicity and accessibility is the method of active thermal control, in which the investigated product is subjected to pulsed thermal action by means of a source of thermal loading. The amplitude, shape and time variation of temperature signals serve as informative parameters that allow an operator or an automated system to detect certain defects and evaluate their parameters. With all the availability of pulsed thermal control, the most difficult component is associated with specialized computer programs for processing experimental data and determining the parameters of a delamination defect. The aim of the study is to create a computer model of the thermal state of a bimetallic plate in the presence of an air bubble between the layers and, through computer simulation, to determine the size of defects during active pulse thermal non-destructive testing of steel-aluminum plates. Materials and methods. When performing the work, the methods of mathematical and computer modeling were used. The created software using the development tools of the MATLAB package was based on known methods for obtaining an approximate solution to a boundary value problem on a computer using the finite difference method. Results. A mathematical model has been developed, an algorithm for solving a boundary value problem, and a computer program has been created that allows simulating a pulse thermal control to determine the parameters of a delamination defect in a bimetallic plate. Conclusion. It was found that it is more efficient to measure the temperature difference from the side where the defect is located and the multilayer plate is heated. Heating the plates from the side opposite to the defect and their further cooling showed significantly lower efficiency in terms of obtaining a useful temperature signal. It is shown that in the presence of a defect, the greater the loading heat flux and the defect size, the greater the value of the useful signal determined by the temperature difference on the measured surface.