Infrared Thermography Testing Research Articles

Intelligent Detection Algorithm Based on 2D/3D-UNet for Internal Defects of Carbon Fiber Composites

ABSTRACT Infrared thermography testing (IRT) has been widely used in the defect detection of composite materials. However, the identification of defects characteristics is unsatisfying due to the interference of factors such as uneven background and noise in the original thermal image sequence. A novel thermography-based defect detection method with the semantic segmentation network is proposed to enhance the defect contrast and extract perfect features. To Figure out the abnormal distribution of temperature field in thermal images, AG-UNet was used with a spatial self-attention gate module to extract spatial features of thermal images. The 3D-UNet network was obtained by the 3D convolution module and the temporal convolution module to extract thermal temporal and spatial features simultaneously which could help the defect segmentation in thermal videos. Compared with traditional algorithms such as principal component analysis (PCA), thermographic signal reconstruction (TSR), and fast Fourier transform (FFT), defects detection results were significantly enhanced with the proposed method, and defects of smaller diameter-to-depth ratio can be detected by deep learning models.

The effective on intradermal acupuncture based on changes in biological specificity of acupoints for major depressive disorder: study protocol of a prospective, multicenter, randomized, controlled trial

BackgroundAntidepressants still have some side effects in treating major depressive disorder (MDD), and acupuncture therapy is a complementary therapy of research interest for MDD. Acupoints are sensitive sites for disease response and stimulation points for acupuncture treatment. Prior studies suggest that the biological specificity of acupoints is altered in physiological and pathological situations. Therefore, we hypothesize that the biological specificity of acupoints is associated with the diagnosis of MDD and that stimulating acupoints with significant biological specificity can achieve a better therapeutic effect than clinical common acupoints. This study aims to investigate the efficacy and safety of intradermal acupuncture (IA) treatment for MDD based on changes in the biological specificity of acupoints.MethodsThe first part of the study will enroll 30 MDD patients and 30 healthy control (HC) participants to assess pain sensitivity and thermal specificity of MDD-related acupoints using a pressure pain threshold gauge (PTG) and infrared thermography (IRT). The potentially superior acupoints for treating MDD will be selected based on the results of PTG and IRT tests and referred to as pressure pain threshold strong response acupoints (PSA) and temperature strong response acupoints (TSA).The second part of the study will enroll 120 eligible MDD patients randomly assigned to waiting list (WL) group, clinical common acupoint (CCA) group, TSA group, and PSA group in a 1:1:1:1 ratio. The change in the Patient Health Questionnaire-9 Items (PHQ-9), the MOS item short-form health survey (SF-36), pressure pain threshold, temperature of acupoints, and adverse effects will be observed. The outcomes of PHQ-9 and SF-36 measures will be assessed before intervention, at 3 and 6 weeks after intervention, and at a 4-week follow-up. The biological specificity of acupoint measures will be assessed before intervention and at 6 weeks after intervention. All adverse effects will be assessed.DiscussionThis study will evaluate the therapeutic effect and safety of IA for MDD based on changes in the biological specificity of acupoints. It will investigate whether there is a correlation between the biological specificity of MDD-related acupoints and the diagnosis of MDD and whether stimulating strong response acupoints is superior to clinical common acupoints in the treatment of MDD. The study’s results may provide insights into the biological mechanisms of acupuncture and its potential as a complementary therapy for MDD.Clinical Trial RegistrationClinicalTrials.gov, identifier: NCT05524519.

A Review of NDT Methods for Wheel Burn Detection on Rails.

Wheel burn can affect the wheel-rail contact state and ride quality. With long-term operation, it can cause rail head spalling or transverse cracking, which will lead to rail breakage. By analyzing the relevant literature on wheel burn, this paper reviews the characteristics, mechanism of formation, crack extension, and NDT methods of wheel burn. The results are as follows: Thermal-induced, plastic-deformation-induced, and thermomechanical-induced mechanisms have been proposed by researchers; among them, the thermomechanical-induced wheel burn mechanism is more probable and convincing. Initially, the wheel burns appear as an elliptical or strip-shaped white etching layer with or without deformation on the running surface of the rails. In the latter stages of development, this may cause cracks, spalling, etc. Magnetic Flux Leakage Testing, Magnetic Barkhausen Noise Testing, Eddy Current Testing, Acoustic Emission Testing, and Infrared Thermography Testing can identify the white etching layer, and surface and near-surface cracks. Automatic Visual Testing can detect the white etching layer, surface cracks, spalling, and indentation, but cannot detect the depth of rail defects. Axle Box Acceleration Measurement can be used to detect severe wheel burn with deformation.

Shape-stable composite phase change materials encapsulated by lignin-based ordered porous carbon for thermal energy storage

This paper showed two bio-based shape-stable composite phase change materials (PCMs) which were prepared through a convenient vacuum impregnation method. Lignin-based ordered porous carbon (LOC) was the porous supporting material, polyethylene glycol (PEG) and paraffin (PA) was the phase change substance in this work. The maximum loading of PCMs in the obtained LOC/PEG and LOC/PA are 70% and 75%, respectively, and their phase transition enthalpy (ΔHm) are also as high as 81.5 J·g−1 and 88.5 J·g−1, respectively. When the loading amount is the same as 60%, the thermal conductivity of LOC/PEG is 0.5029 W/mK, which is a 50.3% improvement over PEG. The thermal conductivity of pure PA is 0.3430 W/mK, and the thermal conductivity of LOC/PA is 0.5847 W/mK, an increase of 70.5% compared to paraffin. In addition, the obtained LOC/PA showed better thermal management capabilities and better thermal stability after infrared thermography tests compared to LOC/PEG. Considering the low cost and excellent properties, the obtained lignin-based ordered porous carbon composite phase change material has a promising future for practical applications in thermal energy storage.

Study of multi-long-pulse thermography using high-power fiber lasers

Active infrared thermography tests are performed using a high-power continuous fiber laser as the excitation source. Multi-long-pulses (MLPs) are used to detect deep defects in samples with reduced heating. Simulation results are compared to theoretical predictions based on 1D heat conduction equations. Different excitation modes are compared. Thermal images are processed using pulsed phase thermography and principal component thermography (PCT), showing that the combination of MLP thermal excitation and PCT data analysis provides better defect detection capability and reduces the specimen’s surface temperature in comparison to conventional pulsed thermography.

Effect of coolant pulsation on film cooling performance on flat plate

• Large eddy simulation was used for investigating square-wave pulsating film cooling on flat plate. • The experiment of pulsating film cooling was carried out. • Evolution of coherent structures in pulsating film cooling was analyzed. Combined with infrared thermography tests, large eddy simulation was used to study the square-wave pulsating film cooling on flat plate at the time-averaged blowing ratios of 0.5 and 1.5. The effects of two pulsating parameters including frequency and amplitude were discussed in detail. At low blowing ratio, the introduction of coolant pulsation leads to the decrease of cooling effectiveness, and the effect of pulsating amplitude is much more pronounced than frequency. At high blowing ratio, cooling effectiveness can be enhanced by coolant pulsation at low amplitude, but reduced at high amplitude. As the typical vortex structure in pulsating film cooling, the starting vortex is formed as the jet is turned on. The interaction between hairpin vortex and starting vortex shows that, at high pulsating amplitude, the starting vortex can help coolant detach from the wall, and has an adverse influence on cooling performance. The statistical characteristics and power spectrum density of instantaneous velocity were investigated. It was found that the introduction of coolant pulsation can result in the increases of eddy energy and turbulent kinetic energy in the near filed region, but this effect becomes weaker and weaker as the streamwise distance increases.

Study on the interaction between coolant pulsation and recirculation vortexes by large-eddy simulation

In the recirculation zone behind the bluff-body, LES method was used to study the interaction mechanism of between the square-wave pulsating film cooling jet and recirculation vortexes. Combined with infrared thermography test results, having a detailed analysis at the time-averaged blowing ratios of 0.5 and 1.5. In model A, at low blowing ratio, the introduction of pulsating jet results in the decrease of cooling effectiveness, and can obviously reduce the turbulent kinetic energy (TKE) at low frequency. At high blowing ratio, pulsating jet at low amplitude can improve film cooling effectiveness, while has adverse effect at high amplitude, the region with high TKE level is obviously elevated and the introduction of pulsation results in the increase of TKE. In model B, at two blowing ratios, film cooling effectiveness can be improved by pulsating jet at low amplitude, but reduced at high amplitude. The effect of pulsating jet on TKE is not obvious at low blowing ratio, while at high blowing ratio, the region with high TKE level is obviously elevated and the introduction of pulsation results in the increase of TKE. In the time-averaged flow field, the entrainment of recirculation vortexes plays a dominant role in the near-wall region. In two models, the introduction of pulsating jet has almost no effect on the recirculation vortexes and velocity profiles. The results show that the varying regularity of film cooling can be explained by the synergistic relationship between velocity field and temperature field, and the pulsating amplitude and frequency play different roles under different conditions respectively.

Multi-label classification algorithms for composite materials under infrared thermography testing

ABSTRACT The key idea in this paper is to propose multi-labels classification algorithms to handle benchmark thermal datasets that are practically associated with different data characteristics and have only one health condition (damaged composite materials). A suggested alternative approach for extracting the statistical contents from the thermal images, is also employed. This approach offers comparable advantages for classifying multi-labelled datasets over more complex methods. Overall scored accuracy of different methods utilised in this approach showed that Random Forest algorithm has a clear higher performance over the others. This investigation is very unique as there has been no similar work published so far. Finally, the results demonstrated in this work provide a new perspective on the inspection of composite materials using Infrared Pulsed Thermography.

SDNET2021: Annotated NDE Dataset for Subsurface Structural Defects Detection in Concrete Bridge Decks

Annotated datasets play a significant role in developing advanced Artificial Intelligence (AI) models that can detect bridge structure defects autonomously. Most defect datasets contain visual images of surface defects; however, subsurface defect data such as delamination which are critical for effective bridge deck evaluations are typically rare or limited to laboratory specimens. Three Non-Destructive Evaluation (NDE) methods (Infrared Thermography (IRT), Impact Echo (IE), and Ground Penetrating Radar (GPR)) were used for concrete delamination detection and reinforcement corrosion detection. The authors have developed a unique NDE dataset, Structural Defect Network 2021 (SDNET2021), which consists of IRT, IE, and GPR data collected from five in-service reinforced concrete bridge decks. A delamination survey map locating the areas, extent and classes of delamination served as the ground truth for annotating IRT, IE and GPR field tests’ data in this study. The IRT were processed to create an ortho-mosaic maps for each deck and were aligned with the ground truth maps using image registration, affine transformation, image binarization, morphological operations, connected components and region props techniques to execute a semi-automatic pixel–wise annotation. Conventional methods such as Fast Fourier transform (FFT)/peak frequency and B-Scan were used for preliminary analysis for the IE and GPR signal data respectively. The quality of NDE data was verified using conventional Image Quality Assessment (IQA) techniques. SDNET2021 dataset consists of 557 delaminated and 1379 sound IE signals, 214,943 delaminated and 448,159 sound GPR signals, and about 1,718,083 delaminated and 2,862,597 sound IRT pixels. SDNET2021 addresses one of the major gaps in benchmarking, developing, training, and testing advanced deep learning models for concrete bridge evaluation by providing a publicly available annotated and validated NDE dataset.

Defect detection by laser shear interferometry based on the thermal response of materials with vibratory loading

Laser shear interferometry or shearography is one of the optical and non-contact methods for measuring surface displacements. Shearography can be used in non-destructive testing by applying a kind of excitation such as partial vacuum, mechanical and thermal loadings. Parameters of the excitation techniques significantly affect the test results. In many cases, these loading methods deform the whole surface reducing the detection capability of the technique. This paper considers the vibratory loading method as an alternative to the previously mentioned standard methods. In this method, local heat is generated at the defected area due to the internal and external damping of the piece. A simulation has been conducted using COMSOL software to estimate the generated local heat due to the vibratory loading. The local temperature at the defect area is measured, and the simulation results are validated with an experimental infrared thermography test. The experimental shearography setup is adjusted, and the defects are detected. By comparing the results with those of typical thermal loadings, it has been shown that the fringe patterns obtained by the presented method have higher quality.

Research and application of infrared thermography testing technology for large-scale amusement rides

The operation of large-scale amusement rides is directly related to the safety of the passengers. When an accident occurs involving an amusement ride, the social impact is extremely negative. Therefore, the safety requirements for large-scale amusement rides are extremely high. Condition monitoring and fault diagnosis technologies provide effective ways to ensure the safe operation. Infrared thermal imaging is a common inspection and monitoring technology, which is widely used in electrical and hydraulic machinery systems. However, there is little literature about the application of infrared thermography (IRT) in large-scale amusement rides and a lack of analysis and evaluation methods for infrared inspection results. In order to expand this technology to the field of large-scale amusement rides, it is necessary to research the temperature increase characteristics of key components and develop corresponding technical standards. In the current study, the temperature variation characteristics of the electrical and hydraulic systems of large-scale amusement rides are first examined. Subsequently, the first IRT testing standard for amusement rides in China is described, including its main content and technical requirements. Two test cases are provided in this study in order to illustrate the practicability and reliability of infrared thermography testing technology in the large-scale amusement rides industry.

Experimental study on leakage detection of grassed earth dam by passive infrared thermography

The leakage of earth rock dams and dykes is characterized by time-space randomness, concealment and small initial discharge quantity. The time from the beginning of abnormal leakage to the break of a dyke is quite limited. The key to ensure the safety of earth rock dykes is to find and identify the leakages in time. Infrared thermography (IRT) has the advantages of fast visualization, strong mobility and wide coverage, so it is a good choice to detect the leakage outlet of earth rock dams and dykes in flood season. However, there are few reports on detailed research in this field. Fully simulating the real service conditions of earth rock dams in flood season, and considering the influence of turf covering, an earth dam model with leakage tunnels is built, then whole day infrared thermography tests of the outlet of the leakages are carried out at an outdoor laboratory in the lower reaches of the Yangtze River. More refined thermal imaging experiments are carried out in the afternoon and at night respectively. The better condition of using IRT to identify the leakage of earth rock dam is explored, and the thermal image spatial distribution characteristics and temporal varying regularity of the leakage outlets under the conditions of grassed and bare soil are also explored, which can provide some experience and reference for using IRT to identify the leakage of earth rock dams and dykes.

Depth Classification of Defects Based on Neural Architecture Search

As an important part of non-destructive testing, infrared thermography testing is widely used in various fields of industrial development for monitoring the quality of metal parts. Considering the problem of low detection rate of surface defects on steel parts, we explored the application of neural architecture search (NAS) in infrared thermography area for the first time. On the one hand, we compared different time-series temperature features of defect locations in infrared images and validate the performance of three different features such as heating, cooling and full process by machine learning methods. On the other hand, we searched for multilayer perceptron through NAS technology to classify defects with different depths. Experiments have proved that the time-series temperature feature is very effective when used in the depth classification of defects, and the accuracy rate can reach 93% under the verification of traditional machine learning methods. The NAS technique used in this paper can search 100 multilayer perceptrons in a minimum of 121s and achieve 100% defect classification accuracy.

The Effect of Fixing Method on the Result of Ultrasonic Infrared Thermography Testing

Considering the influence of the fixing method of the component in the system on its results in ultrasonic infrared thermography testing, the detection experiments of the cracked plat structure with fixing at one end and fixing at two ends are carried out through different fixing methods of the equivalent structure. The results show that for the same structure to be detected, the more the bounds are fixed, the more the degrees of freedom are restricted, the less ultrasonic energy is dissipated during the inspection process, and the better the inspection effect. The work has positive significance for the selection of detection parameters in ultrasonic infrared thermography testing, helpful to provide some references for it.

Impact of Stationary and Dynamic Conditions on the U-Value Measurements of Heavy-Multi Leaf Walls by Quantitative IRT

Infrared thermography (IRT) has become a commonly applied non-destructive testing method for assessing building envelopes. Like any diagnosis tool, IRT requires an appropriate experience and principle understanding, mainly when the method is used for quantitative analyses. The challenges of the IRT often deal with the dynamic properties of building partitions. Climatic conditions have a certain variability, and the accumulated energy storage in the building components can affect their temperature as well as the calculated thermal performance. This paper aims to analyze how stationary and dynamic regimes of a quantitative IRT test could impact the measured thermal transmittance of heavy multi-leaf walls. Investigation in two European countries with different climatic conditions are reported. In this way, it is discussed which boundary conditions should be guaranteed to provide reliable information about a building envelope using quantitative IRT. In order to check the quality of the measurements, the heat flux meter (HFM) method was also implemented, following the ISO 9869. The research revealed that it could be possible to use short-lasting tests in the climatic conditions of Southern Europe, while long-term tests should be implemented in Northern European countries where climatic conditions are less regular.

Effects of Contact Interface Roughness and Sample Mass on Vibration Characteristics in Ultrasonic Infrared Thermography

Nonlinear vibration plays a vital role in ultrasonic infrared thermography testing due to contact-collision effect between a horn and sample, and the effects of contact roughness and sample mass on vibration characteristics of a horn-sample system are deeply investigated in this paper. A two-degree-of-freedom dynamic model based on GW contact model is proposed for exploring the vibration characteristics of a horn-sample system. Then, the vibration characteristics of the horn and sample are calculated under different contact roughness and different sample mass. The results demonstrate that the contact roughness does not influence vibration characteristic of horn, but there are mainly $2f$ and $3f$ except the first harmonic $f$ in velocity responses of the sample. Besides, the amplitude of sample velocity increases with the increase of real contact area as the contact interface is smoother, and there is a 1.8-fold approximate relation in the three amplitude of harmonic $f$ under different contact roughness. On the other hand, with the increase of sample mass, the harmonic $f$ becomes the main component and higher harmonics decreases little by little. This work will be extraordinarily meaningful to optimize testing parameters and evaluate surface quality of sample in ultrasonic infrared thermography testing.

Long-term hyperalgesia and traumatic neuroma formation in tail-docked lambs

AbstractThis study aimed to determine if tail-docking induces long-term hyperalgesia, chronic pain and histopathological changes in tail stumps of tail-docked lambs. Fifty male lambs of 45 days of age were randomly allocated in two groups. One group of 25 lambs was tail-docked using a hot cautery iron and a second group of 25 lambs was subjected only to handling as a control group (undocked lambs). Prior to tail-docking and at intervals of 15, 30, 60 and 90 days after the procedure, infra-red thermography (IT) and mechanical nociceptive thresholds (MNTs) tests were carried out in both lambs’ tails/stumps, and animals were weighed. In addition, the visual degree of inflammation of tail stumps was evaluated. Finally, animals were slaughtered in a commercial slaughterhouse and tail sections of ten lambs from each group were examined histopathologically. Tail-docking was associated with an inflammatory process according to IT and visual observation in tail stumps at 15 and 30 days post-docking. Tail-docked lambs had lower MNTs than undocked lambs at all evaluated times after tail-docking, indicating the presence of long-term hyperalgesia. Also, traumatic neuroma formation was found in tail stumps of 2/10 tail-docked lambs, and 6/10 presented neuromatous tissue development. It is concluded that tail-docking induces acute and chronic pain in lambs, initially through inflammation, and then via long-term hyperalgesia and traumatic neuroma formation. These long-term findings would have negative implications for the animal welfare of tail-docked lambs.

A Weighted Estimation Algorithm for Enhancing Pulsed Eddy Current Infrared Image in Ecpt Non-Destructive Testing

Non-destructive testing (NDT) plays a crucial role in large scale industrial production such as in the nuclear industry and bridge structures where even a small crack can lead to severe accidents. The pulsed eddy current infrared thermography testing method, as a classic non-destructive testing technology, is proposed to detect cracks in the presence of excitation sources that cause temperature changes in the vicinity of defects, which is higher than normal area. However, in the vicinity of the excitation sources, the temperature is higher than normal even if there is no defect. Traditional infrared image enhancing algorithms do not work efficiently when processing infrared images because the colors in the images represent the temperature. To address this, a novel algorithm is proposed in this paper. A weighted estimation algorithm is proposed because each pixel value has a strong relationship with its neighboring pixels. The value of each pixel is determined by calculating the values of its neighboring pixels with a specific step-size and the correlation coefficients between them. These coefficients are obtained by calculating the differences between the pixels. The experimental results indicated that the outline of the welding defect became significantly clearer after being processed using the proposed algorithm, which can eliminate the errors caused by the excitation source.

Thermal Effects of Acupuncture by the Infrared Thermography Test in Patients With Tinnitus

Previous studies have confirmed the efficacy of acupuncture treatment for tinnitus. However, no relevant studies of the exact mechanism of acupuncture efficacy on tinnitus have been published. Enrolled participants with left-sided tinnitus received acupuncture treatment at TE3 and TE5. The acupuncture session lasted for 30 minutes. The infrared thermography (IRT) test of each participant's bilateral aural regions and visual analog scale scores were taken before and after the first acupuncture treatment session. Fifty-four participants accepted acupuncture treatment and the IRT test. The temperature differentials of both sides were reduced significantly, but the maximum, minimum, and average temperature of bilateral aural regions did not have a significant difference before and after acupuncture session. The acupuncture's effects for tinnitus were associated with the improvement of cochlear blood flow via the IRT test. We have planned a full-scale randomized controlled trial to find out more about the underlying mechanisms of acupuncture for tinnitus.

U-value time series analyses: Evaluating the feasibility of in-situ short-lasting IRT tests for heavy multi-leaf walls

A gap in standardization of quantitative infrared thermography (IRT) directly leads to a lack of measurement pattern for determining in-situ U-values of heavy multi-leaf walls. Three groups of causal factors might influence the estimation of this build quality indicator: operating conditions, thermophysical properties and technical conditions. Focusing on the last one, previous studies underlined the difficulties of measuring below 3 h. In contrast to active IRT, no algorithms have been found to process images, despite playing an important role in the effectiveness and robustness of IRT. The traditional approach involves analysing from 120 to 7200 thermograms with a data acquisition interval of 1 min up to 1 s respectively. The aim of this paper was to critically assess the test duration that is traditionally used. Six real heavy multi-leaf walls were tested under a stationary regime as a stochastic process of underlying data. For the first time, a research based on two U-value time series analyses (statistical tests and a signal modelling technique by MATLAB) demonstrated the feasibility of short-lasting IRT tests. Moreover, this research posed an innovative data management tool to automate this non-destructive testing (NDT) in mid-term, stopping IRT tests in real time once the right level of accuracy was achieved.