Showing papers on "Thermography published in 2014"
TL;DR: A general introduction to infrared thermography and the common procedures for temperature measurement and non-destructive testing are presented and developments in these fields and recent advances are reviewed.
Abstract: The intensity of the infrared radiation emitted by objects is mainly a function of their temperature. In infrared thermography, this feature is used for multiple purposes: as a health indicator in medical applications, as a sign of malfunction in mechanical and electrical maintenance or as an indicator of heat loss in buildings. This paper presents a review of infrared thermography especially focused on two applications: temperature measurement and non-destructive testing, two of the main fields where infrared thermography-based sensors are used. A general introduction to infrared thermography and the common procedures for temperature measurement and non-destructive testing are presented. Furthermore, developments in these fields and recent advances are reviewed.
658 citations
TL;DR: In this article, a review of the state-of-the-art literature and research regarding the passive and active infrared thermography for building diagnostics is presented, with a focus on the building sector, as well as the advantages, limitations and potential sources of errors of IRT employment.
355 citations
TL;DR: In this article, a 3D Raman thermography mapping and modeling approach has been developed to understand the contribution of substrate and GaN/substrate interface thermal resistance to the device thermal resistance.
Abstract: In order to achieve ultra-high radio frequency output power densities in GaN-based transistors new thermal management solutions must be developed for efficient heat extraction, including the use of high thermal conductivity substrates. Integration of GaN devices with the highest thermal conductivity material available, diamond, instead of the standard GaN-on-SiC, can lead to a substantial reduction in device thermal resistance. Current GaN-on-diamond transistors are shown to result in a 40% reduction in peak channel temperature when benchmarked against equivalent GaN-on-SiC transistors, with the potential for even further reductions through optimization. In order to understand the contribution of substrate and GaN/substrate interface to the device thermal resistance, a 3D Raman thermography mapping and modelling approach has been developed. The GaN/diamond interface thermal resistance is found to have the largest contribution to the thermal resistance of current GaN-on-diamond devices.
138 citations
TL;DR: In this article, the authors used active thermography with flash excitation to characterize carbon fiber reinforced polymer (CFRP) specimens with artificial delaminations and with impact damage using four different experimental configurations of flash lamps and IR camera in transmission as well as in reflection alignment.
Abstract: Carbon fiber reinforced polymer (CFRP) specimens with artificial delaminations and with impact damage have been characterized using active thermography with flash excitation. Systematic investigations have been performed in four different experimental configurations of flash lamps and infrared (IR) camera in transmission as well as in reflection alignment. It is shown here that the diffusivities determined for the sound and for the damaged areas give a good measure for damage characterization. Although reflection measurements also give information about defect depth, reflection measurements from only one side are not sufficient for assessing the whole cross section of the specimens. Thus, depending on sample thickness the lateral size of damage could only be determined from reflections measurements from both sides or from transmission measurements. In this paper, measurement accuracy and limits of flash thermography for the investigation of CFRP specimens are presented in detail together with quantitative data concerning the defects.
122 citations
TL;DR: It was determined that environmental factors impact IRT temperature measurements significantly and therefore must be managed to ensure reproducible and accurate readings.
113 citations
TL;DR: In this article, a glass fiber reinforced polymer under low energy impact with particular attention to the influence of fibres orientation and manufacturing defects is investigated, and the results show how the use of an infrared imaging device may be useful in understanding impact damaging mechanisms and establishing the delamination threshold load.
107 citations
TL;DR: In this paper, a model of heat dissipation is presented based on the measurement of the material response for varying heat input for a limited section of the building platform in a commercial system.
99 citations
TL;DR: In this article, an alternative method (Tmax) was proposed to obtain a temperature value of a specific area based on maximal temperature detection instead of considering the average temperature on the selected area.
96 citations
TL;DR: In this article, the authors deal with characterization of the damage and thermomechanical behavior of the Glass Fiber-Reinforced Polymer composite materials (GFRP) submitted to static tensile loadings, using a passive infrared thermography technique.
Abstract: This study deals with characterization of the damage and thermomechanical behavior of the Glass Fiber-Reinforced Polymer composite materials (GFRP), submitted to static tensile loadings, using a passive infrared thermography technique. During mechanical testing, thermal measurements are performed by means of an IR camera. The thermal data post-processing involves the analysis of both the thermal maps and the thermomechanical behavior of the material. The thermal maps analysis allows qualitative evaluation of the created material damage at high stress levels. While the thermomechanical analysis gave us a quantitative evaluation of the material damage, for both low and high stress levels, through definition of a new thermoelastic damage variable.
96 citations
TL;DR: In this article, a combined application of Ground Penetrating Radar and Infrared Thermography (IRT) was used to detect and characterize cracks in pavement and their origins, and the results showed that the first two parameters can be quantitatively evaluated with different sensors, while the latter is usually only qualitatively assessed by visual inspection.
Abstract: Pavement condition is a factor of major interest due to its direct contribution to safety and comfort of the users of the road. Consequently, road inspections imply the evaluation of different parameters such as roughness of the pavement, skid resistance, and presence and condition of cracks. Although the first two parameters can be quantitatively evaluated with different sensors, the latter is usually only qualitatively assessed by visual inspection. This paper deals with this drawback through the combined application of Ground Penetrating Radar and Infrared Thermography to the detection and characterization of cracks in pavement and their origins.
94 citations
TL;DR: In this paper, a statistical correlation method for the optimization of the pulsed thermography inspection is proposed, based on partial least squares regression, which decomposes the thermographic PT data sequence obtained during the cooling regime into a set of latent variables.
Abstract: This paper introduces and tests a statistical correlation method for the optimization of the pulsed thermography inspection. The method is based on partial least squares regression, which decomposes the thermographic PT data sequence obtained during the cooling regime into a set of latent variables. The regression method is applied to experimental PT data from a carbon fiber-reinforced composite with simulated defects. The performance of the regression technique is evaluated in terms of the signal-to-noise ratio. The results showed an increase in the SNRs for 96% of the defects after processing the original sequence with PLSR.
TL;DR: This work presents an approach to automatically create 3D thermal models using multi-perspective measurements with a multimodal camera system consisting of a thermal camera and a depth camera.
Abstract: This work presents an approach to automatically create 3D thermal models using multi-perspective measurements with a multimodal camera system consisting of a thermal camera and a depth camera. Additional attributes such as color can also be added to the model. The paper centers its attention on the geometrical calibration of the cameras and the validation of the results. The design of an adequate calibration target is discussed and different options are evaluated. To expose the applicability of the approach two inspection tasks are used as examples.
TL;DR: In this paper, a noncontact laser lock-in thermography (LLT) technique was developed for detecting surface-breaking fatigue cracks on uncoated steel structures with low surface emissivity.
Abstract: This paper develops a new noncontact laser lock-in thermography (LLT) technique for detection of surface-breaking fatigue cracks on uncoated steel structures with low surface emissivity. LLT utilizes a modulated continuous (CW) wave laser as a heat source for lock-in thermography instead of commonly used flash and halogen lamps. LLT has the following merits: (1) the laser heat source can be precisely positioned at a long distance from a target structure thank to its directionality and low energy loss, (2) a large target structure can be inspected using a scanning laser heat source, (3) no special surface treatment of the target structure is necessary to generate and measure thermal wavefields, (4) thermal image noises created by arbitrary surrounding heat sources can be effectively eliminated and (5) the use of a low peak power laser makes it possible to avoid surface ablation. The LLT system is developed by integrating and synchronizing a modulated CW laser, a galvanometer and an infrared camera. Then, a fatigue crack evaluation algorithm based on a holder exponent analysis is proposed. The performance of the proposed LLT technique is validated through thermal wavefield imaging and fatigue crack evaluation tests on an uncoated steel plate with emissivity of 0.8 and a welded T-shape joint with emissivity of 0.7. Test results confirm that thermal wavefield images are effectively captured even when surface-reflected background noises and laser-generated thermal waves coexist, and surface-breaking cracks are successfully evaluated without any special surface treatment.
TL;DR: In this article, the results of laboratory and in situ tests to assess facade plaster detachments using dynamic thermography are presented and compared with numerical simulation results, where the authors apply infrared thermography to a rapid non-destructive diagnosis.
Journal Article•
TL;DR: Evaluation of possible biophysical methods and approaches for registering various non-ionizing radiation (NIR) wave types of the human body in the electromagnetic range helps understand in general how electromagnetic radiation interacts with water and establishes the structural alterations of water.
Abstract: This paper presents the results of evaluation of possible biophysical methods and approaches for registering various non-ionizing radiation (NIR) wave types of the human body in the electromagnetic range. Many types of NIR (electromagnetic waves, infrared radiation, thermo radiation, bioluminescence) emitted from the human body were reviewed. In particular the results of spontaneous biophoton emission and delayed luminescence from the human body are submitted along with i nfrared thermography (IRT) results. It was shown that 1 cm 2 of skin generally emits ~85 photones for 1s. The intensity of biophoton emission ranges from 10 ?19 to 10 ?16 W/cm 2 (approx. ~1–1000 photons . cm -2. s -1 ). The specific photon emission from part of the human thumb was detected as a spectrum of various colours with the method of Color coronal spectral analysis on a device with an electrode made ??of polyethylene terephthalate (PET hostafan) with applied electric voltage of 15 kV, electric impulse duration 10 ms, and electric current frequency 15 kHz. It was established that photons corresponding to a red color emission of the visible electromagnetic spectrum have energy at 1.82 ?V. The orange color of the visible electromagnetic spectrum has energy at 2.05, yellow – 2.14, blue-green (cyan) – 2.43, blue – 2.64, and violet – 3.03 eV. The reliable result measurement norm was at E ? 2.53 eV, while the spectral range of the emission was within 380–495 nm and 570–750 nm±5 nm. Some important physical characteristics were also demonstrated (energy of hydrogen bonds, wetting angle, surface tension) of water by the methods of non-equilibrium energy (NES) and differential non-equilibrium energy (DNES) spectrum of water, that helps understand in general how electromagnetic radiation interacts with water and establishes the structural alterations of water. Keywords: electromagnetic waves, infrared radiation, thermo radiation, bioluminescence, color coronal spectral analysis, NES, DNES
TL;DR: Three image segmentation methods: k-mean, fuzzy c-means and level set are discussed and compared and according to the results, level set method is a more accurate approach and has potential to extract almost exact shape of tumors.
Abstract: Breast thermography is a physiological test that provides information based on the temperature changes in breast. It records the temperature distribution of a body using the infrared radiation emitted by the surface of that body. Precancerous tissue and the area around a cancerous tumor have higher temperature due to angiogenesis, and higher chemical and blood vessel activity than a normal breast; hence breast thermography has potential to detect early abnormal changes in breast tissues. It can detect the first sign of forming up cancer before mammography can detect. The thermal information can be shown in a pseudo colored image where each color represents a specific range of temperature. Various methods can be applied to extract hot regions for detecting suspected regions of interests in the breast infrared images and potentially suspicious tissues. Image segmentation techniques can play an important role to segment and extract these regions in the breast infrared images. Shape, size and borders of the hottest regions of the images can help to determine features which are used to detect abnormalities. In this paper, three image segmentation methods: k-means, fuzzy c-means and level set are discussed and compared. These three methods are tested for different cases such as fibrocystic, inflammatory cancer cases. The hottest regions of thermal breast images in all cases are extracted and compared to the original images. According to the results, level set method is a more accurate approach and has potential to extract almost exact shape of tumors.
TL;DR: In this paper, a closed loop Pulsating Heat Pipe (PHP) with nonintrusive spatial and temporal measurement of tube wall temperature by high-resolution infra-red thermography (IRT) has been attempted.
TL;DR: In this article, in-situ thermal transmittance of walls, ceiling and roof were continuously monitored and each element was characterized by its own thermal insulation capability, and the proposed quantitative methodology was applied to assess the energy losses due to thermal bridges.
Abstract: Thermal infrared imaging is a valuable tool to perform non-destructive qualitative tests and to investigate buildings envelope thermal-energy behavior. The assessment of envelope thermal insulation, ventilation, air leakages, and HVAC performance can be implemented through the analysis of each thermogram corresponding to an object surface temperature. Thermography also allows the identification of thermal bridges in buildings’ envelope that, together with windows and doors, constitute one of the weakest component increasing thermal losses. A quantitative methodology was proposed in previous researches by the authors in order to evaluate the effect of such weak point on the energy balance of the whole building. In the present work, in-field experimental measurements were carried out with the purpose of evaluating the energy losses through the envelope of a test room experimental field. In-situ thermal transmittance of walls, ceiling and roof were continuously monitored and each element was characterized by its own thermal insulation capability. Infrared thermography and the proposed quantitative methodology were applied to assess the energy losses due to thermal bridges. The main results show that the procedure confirms to be a reliable tool to quantify the incidence of thermal bridges in the envelope thermal losses.
Journal Article•
TL;DR: In this article, the results of evaluation of possible biophysical methods for registering of infrared thermal field of the human body in the electromagnetic range were presented, and the spectral ranges of non-equilibrium energy (NE) and differential NE spectrum of water were analyzed.
Abstract: This paper presents the results of evaluation of possible biophysical methods for registering of infrared thermal field of the human body in the electromagnetic range Many types of emissions (electromagnetic waves, infrared radiation, thermo radiation, bioluminescence) emitted from the human body were researched There were shown the results with i nfrared thermography (IRT) results Some important physical characteristics were also demonstrated (energy of hydrogen bonds, wetting angle, surface tension) of water by the methods of non-equilibrium energy (NES) and differential non-equilibrium energy (DNES) spectrum of water, that helps understand in general how electromagnetic radiation interacts with water and establishes the structural alterations of water The spectral ranges of NES and DNES are in middle infrared range Keywords: electromagnetic waves, infrared thermal field, NES, DNES
TL;DR: In this paper, the authors used infrared thermography to detect moisture content change in adhered facade claddings as a preliminary inspection technique, and the results of numerical simulations performed afterwards.
TL;DR: The thermal response of bulk tissue as a function of wavelength from 700 to 1064 nm was reported and Monte Carlo simulations were used to verify the thermal response measured and predict damage thresholds based on the response.
Abstract: The time-temperature effects of laser radiation exposure are investigated as a function of wavelength. Here, we report the thermal response of bulk tissue as a function of wavelength from 700 to 1064 nm. Additionally, Monte Carlo simulations were used to verify the thermal response measured and predict damage thresholds based on the response.
TL;DR: In this article, two systems, real-time and off-line, are proposed to monitor the temperature variations and analyze hot regions in the electrical assets using infrared thermograms, and a redness area based algorithm is also proposed to analyze the hot regions and also to estimate rate of change of hotness in electrical assets for early detection and prediction of faults.
TL;DR: In this paper, two types of windows (wood and aluminum framed) were analyzed, showing that the difference between two-dimensional and three-dimensional simulations is not so high to justify the vast difference that exists instead in terms of calculation time.
TL;DR: The stake of this work is to show how advanced pre- and post-processing tools, commonly used for pulse-heating, can be applied to step- heating.
Abstract: Several advanced pre- and post-processing tools have been developed over the last two decades, to enhance the performance of time-resolved pulse thermography, in terms of defect detection and characterisation. Two of the most efficient techniques are the Thermographic Signal Reconstruction, proposed in 2001, including a recent development based on the use of the polynomial coefficient images proposed in 2014, and the early detection of emerging contrast, proposed in 1994. The stake of this work is to show how these tools, commonly used for pulse-heating, can be applied to step-heating. The work was divided in two parts: the theoretical and analytic study is reported in the present article; the matching experimental results are discussed in a second, separate article.
TL;DR: This review of the use of thermographic technique in equines introduces the principles upon which infrared radiation and thermoregulatory physiology are based and describes the instrumentation used and its practical use.
TL;DR: In this paper, the fatigue behavior of AZ31B magnesium alloy welded joint during high cycle fatigue test was investigated by infrared thermography and the theoretical models were formulated to explain the observed temperature evolution.
18 Feb 2014
TL;DR: In this article, an experimental design for IR measurements of a laser-based powder bed fusion additive manufacturing (AM) process is presented. But the experimental design is not discussed. But it is shown that IR measurements can provide direct process metrology, as well as data necessary for the verification of physics-based models.
Abstract: Additive manufacturing (AM) has the potential to revolutionize discrete part manufacturing, but improvements in processing of metallic materials are necessary before AM will see widespread adoption. A better understanding of AM processes, resulting from physics-based modeling as well as direct process metrology, will form the basis for these improvements. Infrared (IR) thermography of AM processes can provide direct process metrology, as well as data necessary for the verification of physics-based models. We review selected works examining how IR thermography was implemented and used in various powder-bed AM processes. This previous work, as well as significant experience at the National Institute of Standards and Technology in temperature measurement and IR thermography for machining processes, shapes our own research in AM process metrology with IR thermography. We discuss our experimental design, as well as plans for future IR measurements of a laser-based powder bed fusion AM process.
TL;DR: In this article, the authors used infrared thermography to assess the fatigue behavior and the corresponding damage states of a textile polymeric composite plate, as a prerequisite step in the development of damage based life prediction models for such advanced composite materials.
Abstract: The focus of this study is to assess, using infrared thermography, the fatigue behavior and the corresponding damage states of a textile polymeric composite plate, as a prerequisite step in the development of damage based life prediction models for such advanced composite materials. Monotonic (quasi-static) loading test results confirmed that the dominant damage mechanism is cracking in the braider yarns, which was monitored using thermographic images and confirmed by edge replication microscopic observations. Fatigue results confirmed that the saturation of braider yarn cracks during cyclic loading corresponded to changes in the stiffness degradation rate as well as the surface temperature profile. This was confirmed by edge replication and scanning electron microscopic analysis. The reported results and observations provide an important step in the validation of thermography as a powerful non-destructive evaluation tool for monitoring the development of fatigue damage as well as predicting the damage states of laminated composite materials in general, and braided polymeric composite materials in particular.
TL;DR: In this article, an investigation of CFRP-concrete samples containing various kinds of artificial and loading cracks at the concrete surface was performed, and active infrared thermography (IRT) was adopted for the thermal observation.
Abstract: Bond defects due to the development of cracks in concrete strengthened externally with CFRP can degrade the integrity of the composite system. Previous studies have addressed this issue by using different non-destructive testing (NDT) methods, and most have attempted to determine a reliable method to detect cracks and recognize their properties. Infrared thermography (IRT) has emerged as an effective method to detect the propagation of cracks and determine their width in the substrate structure of the composite system. This paper presents the findings of an investigation of CFRP-concrete samples containing various kinds of artificial and loading cracks at the concrete surface. Different types of FRP fabrics and laminate combinations were used in the design. Active IRT was adopted for the thermal observation. Thermal pulses were applied with different angles to enhance crack measurement. The results show that the technique is capable of detecting the location and width of cracks quite adequately. Moreover, the location of the external heating and interval pulse has a considerable effect on crack detection. However, the results show that it is not possible to determine crack depth by using pulsed IRT.