Infrared Thermography Method Research Articles

Evaluation of infrared thermography methods for analysing the damage behaviour of adhesively bonded repair solutions

For subsurface damage inspection of bonded repair patches, non-destructive inspection methods are needed. Additionally, monitoring the subsurface damage progress under loading is essential to gain knowledge for the repair design process. Infrared thermography is a temperature-based non-destructive inspection method. The method of optical lock-in thermography is commonly used for the steady-state detection of subsurface inhomogeneities while passive thermography can be used to monitor changes in surface temperature due to thermal energy dissipation. Here, the progress of subsurface damages is of interest. Both methods are analysed in terms of their applicability to monitor subsurface damage propagation under loading. This paper shows how these methods contribute to understand the degradation process of a mechanically loaded patch repair.

Performance analysis of the infrared thermography method for complex phase diagrams estimation

An infrared thermography method for the fast estimation of phase diagrams is progressively being challenged to assess the extent of its potential. Being simple, fast and at relatively low cost, it has successfully been applied to binary systems of organic materials of increasing complexity. A test campaign is now undergoing, aiming at evaluating the influence of experimental parameters on the efficiency of the method. In this work, the impact of the acquisition frequency and the heating rate on the accuracy of the estimated phase diagrams is assessed. Based on the estimation of the phase diagrams of three binary systems of fatty alcohols and fatty acids, the accuracy deviation for phase transitions detection is evaluated in comparison with measurements made by differential scanning calorimetry. Optimized parameters both in terms of heating and acquisition rates are determined to further improve the method.

A fast and low-cost dynamic calorimetric method for phase diagram estimation of binary systems

A dynamic calorimetric method based on infrared thermography has been used for the phase diagram estimation of binary systems of fatty organic materials. Its promising results make of this innovative method an interesting asset in applications with time constraints. In order to provide a calorimetry method with satisfactory performance and the lowest time consumption and cost, a test campaign is undergoing. This campaign aims at evaluating the influence of operating conditions on the performances of the method. In that frame, the phase diagrams estimated using a high-end photon detector and a low-cost microbolometer are compared. The assessment of the accuracy and reliability of phase transitions detection is made based on the study of 4 binary systems of fatty acids and fatty alcohols. Differential scanning calorimetry is used for the validation of the experimental phase diagram, and further works are identified in the light of innovative data obtained using the infrared thermography method.

Methods for automated crack length detection in fracture mechanical fatigue tests of unreinforced polymers

The continuous measurement of crack growth during fracture mechanical fatigue tests is of great importance for an accurate lifetime estimation of components. Different methods for an automatic crack length detection exist for linear elastic materials and electrically conductive materials like metals (ASTM International E 647-11, 2011; International Standard ISO 15850, 2002a) or fiber reinforced composites (ASTM International D5528-13, 2013; International Standard ISO 15024, 2001). However, there is no satisfying automatic system for the crack length detection in polymers. For polymers, it is still state of the art to measure the crack length manually by the use of a travelling microscope. Besides other drawbacks, this way of measuring provides only a limited number of data points. Therefore, the aim of this work was to develop methods for the automated crack length detection in these materials. Two measuring techniques were examined regarding their general applicability: (i) infrared thermography (IRT) and (ii) digital image correlation (DIC). For the validation, three types of thermoplastics (Polyvinylchloride (PVC-U), Polymethylmethacrylate (PMMA) and Polyoxymethylene (POM)), which show rather different mechanical behavior, were tested. Satisfactory correlations were obtained for both DIC and IRT method. In general, all tested systems showed good results and the determined average difference in the measured crack lengths was smaller than 5.5 %. Hence, the investigated methods based on DIC and IRT are highly interesting for an automation of fatigue crack growth measurements of polymers.

Assessment of Thermal Performance of Textile Materials Modified with PCM Microcapsules Using Combination of DSC and Infrared Thermography Methods.

The aim of the study was the combination of two measurement methods, the differential scanning calorimetry (DSC) and infrared thermography to evaluate thermal performance of woven and knitted fabrics coated with acrylic pastes containing 20% (P/20) and 40% (P/40) of microcapsules of phase change materials (MPCM) with transition temperatures of 28 °C (MPCM28) and 43 °C (MPCM43). The DSC analysis showed that the phase transition processes for materials modified with pastes P/20 occur in a narrower temperature range than those modified with P/40 pastes. The initial temperatures TOnset (S-S) and TOnset (S-L) are higher for materials modified respectively with pastes P/20 and P/40. The melting and crystallization enthalpy values of both P/20 coated materials are lower by about 45% and 35% compared to P/40. Infrared thermography analysis showed that materials modified with P/20 are heating up faster than modified with P/40 for both MPCM. In the cooling process for modified fabrics the highest temperature decrease was observed in the first 30s. Materials modified with paste P/40 were cooled more slowly in comparison with paste P/20, both for MPCM28 and MPCM43.

Determination of the Technical Condition of Industrial Chimneys by the Passive IR Thermography Method

Determination of the Technical Condition of Industrial Chimneys by the Passive IR Thermography Method

Integrated micro tesla magnetic sensor for detecting photovoltaic cells failure

Recently more attention on the failure of PV systems has been paid and more reports have been found in PV related papers. Various methods to detect failure of PV module have been developed; They are visual method, I-V characteristic method, electroluminescence (EL) method, UV fluorescence method, signal transmission method, IR thermography method, photoluminescence (PL) method. However, each method has some limitations. Developing a new alternative diagnostic method of PV cells will be required for efficient operation of PV system. The proposed method uses μ-tesla magnetic sensor (MI-CB-1DM) to detect failure in a PV cell. The experimental design carried out in this study covered two stages. In the first stage, we developed a method for detecting faults in PV cells using the μ-tesla magnetic sensor method. In this second stage a calculation will be made to determine the current level due to the failure of the PV cell. The results show that Bx at the lower busbar in the degraded module has smaller magnetic density than the upper busbar. No obvious difference can be seen in the Bx and By profiles between the normal and degraded cells.

Heat transfer characteristics of swirling impinging jet-arrays issued from nozzle plates with and without webbed grooves

Heat transfer characteristics of the swirling impinging jet-arrays issued from the nozzle plates without and with the # and ※patterned grooves were comparatively studied. Each swirling jet was induced by the twisted tape with 1 or 2 twist pitches in the nozzle. The detailed Nusselt number distributions over the impingement surface for the six types of swirling jet-arrays were measured using the infrared thermography method at jet Reynolds numbers and nozzle-to-plate distances between 1500-20000 and 0.1–8 nozzle diameters respectively. A selective set of experimental results illustrated the effects of jet Reynolds number, nozzle-to-plate distance and the grooves on the local and regionally averaged heat transfer performances with the heat transfer uniformity over the impingement surface examined. In conformity with the effects of jet Reynolds number and nozzle-to-plate distance disclosed by the present study, a set of heat transfer correlations that evaluated the average Nusselt numbers over the central jet region of the swirling impinging jet-arrays issued from the nozzle plates without and with the grooves were generated.

Single-Pulse Avalanche Failure Investigations of Si-SJ-mosfet and SiC-mosfet by Step-Control Infrared Thermography Method

The step-control infrared thermography method was proposed to investigate comprehensive single-pulse avalanche failure details of Si-superjunction (SJ) mosfet and SiC- mosfet . By this method, the damage location and even its shift in real time during the whole avalanche process can be observed. It is shown that, for the Si-SJ- mosfet , the avalanche damage location is extended from the cell region toward termination region with the increased avalanche time. The parasitic bipolar junction transistors at the cell corner near the termination are triggered due to the increased p-base resistances under relatively high temperature. However, for SiC- mosfet , the avalanche location is always kept within the cell region mainly due to insensitive breakdown voltage dependence on temperature. As a result, its failure site is found to locate at the source pad near the wire bond, likely due to the lattice temperature beyond the melting limit of aluminum contacts. Finally, the schemes to improve avalanche robustness, including the two different N -Epitaxy layers for Si-SJ- mosfet and the double source wire bonds for SiC- mosfet , have been proposed and verified basing on different failure mechanisms.

Heat Criterion of the Change of Strain-Hardening Stages in Austenitic Stainless Steel

The infrared thermography method was used to study changes in the temperature of austenitic stainless steel in the process of tensile deformation. It was revealed that the temperature of the sample stops growing in the transition region between the linear stages of strain hardening. This phenomenon can be connected with a change in the entropy of the deformed medium as a result of a reconstruction of the ordered autowave structures. In the region of true deformation exceeding 0.4, a phenomenon of discontinuous flow (Portevin–Le Chậtelier effect) is observed, which is accompanied by the motion of the single fronts of localized deformation. The observed fronts are heat sources, and the value of the temperature at the arbitrary point of the sample is determined by its position relative to the front of deformation.

Detecting leakage current by infrared thermography method

<span>An alternating current leakage can happen in electrical installation such as switchgear panel. If it’s not being detected earlier and address properly, it might lead to unintended incident or accident such as fire, electric shock, and power supply trip. Occasionally, if it appears, tracing its root cause can be difficult. The conventional method is by isolating one by one of the electrical loads with aids of multimeter and clamp meter. <span class="apple-converted-space"> </span>Unfortunately, this conventional method could be a tedious job for installations involved in numbers of electrical panels. Therefore, an alternative method is deeming necessary. This paper describes research works on Infrared Thermography (IRT) as a new method in detecting leakage current as aids in resolving related electrical problems. The scope of study mingling around to determine IRT’s suitable parameters that represent the identification of leakage current, derive new mathematical equation correlating leakage current to IRT and conduct experiment accordingly. Two new equations derived which are leakage current relationship to thermogram and infrared net radiation power. The results of experiment adherence to the hypothesis drawn. Consequently, helps to realize predictive maintenance concept by detecting the root cause of leakage current ahead its triggering points of unintended incident and accident.</span>

Comparative Study of Indoor Infrared Thermography Method to Estimate the Overall Thermal Resistance for Building Envelope Systems

Comparative Study of Indoor Infrared Thermography Method to Estimate the Overall Thermal Resistance for Building Envelope Systems

Application of infrared thermography for in-situ determination of building envelope thermal properties

Thermal resistance of building envelope systems plays an important role in the building energy evaluation, design, and retrofit efforts; in-situ determination of the thermal resistance is highly desired for obtaining a realistic building energy performance picture. The conventional heat flow meter method for measuring thermal resistance requires a considerable number of sensor installations and also an appropriate definition of the homogeneous wall area. Therefore, a simpler and more practical measurement method is needed. Recent studies indicate that the infrared thermography method has the potential to be used as a quantitative technique for thermal resistance measurement. However, there are limitations in the previously developed infrared thermography method that may lead to difficulties in practical application. In the study reported in this paper, an innovative infrared thermography model is proposed and its effectiveness is validated by comparison with the heat flow meter method. A convective heat transfer coefficient model is also proposed, which can particularly be used for low-rise residential buildings. A recommended testing procedure is then given at the end of the paper for appropriate use of the proposed measurement method.

Semi-Quantitative Comparison of Infrared Thermography with Indocyanine Green Imaging in Porcine Intestinal Resection

BackgroundThe quality of intestinal blood supply is extremely important for healing of intestinal anastomoses. During the surgery the blood supply of the intestine may appear sufficient even though the microperfusion is not fully adequate. The degree of blood supply of remaining intestinal segment and the positioning of the resection margins is estimated subjectively by the surgeon's experience or objectively by means of indocyanine green fluorescence imaging. The subject of our study is the evaluation of the infrared thermal imaging as another supportive non-invasive imaging method in assessment of intestinal blood supply, and to compare surgeon's decisions of the position of resection line with information obtained by infrared thermal imaging and by indocyanine green fluorescence imaging. MethodsA pilot study on thermal imaging measurements was done in a porcine model. The infrared thermocamera Workswell WIC 640 was used in our study. The thermal imaging was correlated with the indocyanine green imaging method ICG NOVADAQ and with surgeon's subjective expert decisions of the places of resection lines. Fifteen monitored resections were performed on three experimental porcine models. ResultsBased on the data evaluated, experience of the surgical team and the post-operative conditions of the porcine models, we conclude that the thermal imaging is a useful tool for determination of the optimal intestinal resection margins, and thus contributes to lowering anastomotic complications rate in colorectal surgery. The results show relatively high consistency between the used imaging techniques. Both methods showed ischemic regions of the intestine at a comparable level. The IRT methods showed even a slightly higher match with the surgeon's rating. ConclusionBased on experiments, the infrared thermography can be considered as one of complementary imaging methods suitable for use during anastomosis surgery. The sensitivity and versatility of the infrared thermography method was demonstrated. There was confirmed agreement in obtained information about the position of area with maximal blood insufficiency obtained by IRT with the information obtained by using the ICG method.

Use of the infrared thermography method to develop discharging rules for lithium polymer batteries

Use of the infrared thermography method to develop discharging rules for lithium polymer batteries

BOVINE WELLFARE HANDLED IN ADAPTED CORRAL WITH UNCONVENTIONAL MATERIALS

ABSTRACT This study aimed at evaluating bovine behavioral parameters managed in crowding pens built with modular panel of reforestation wood and homogeneous particle sheets of sugarcane bagasse and in conventional wooden crowding pens. The animals treated had their body surface temperature measured by the infrared thermography method and the behavior evaluated through the flight time parameters and the behavior score in the crowding pens. The results indicated that the animals managed in these buildings showed no difference in the behavioral parameters, but the mean and maximum superficial body temperatures were lower in the animals managed in the crowding pens of modular panel.

Non-destructive testing of light armours of CFRP after ballistic impacts by IR thermography methods

Multi-layered composites are frequently used in many military applications as constructional materials and light armours protecting personnel and armament against fragments and bullets. One of the many methods used in non-destructive testing of composites is active infrared thermography. In active thermography it is necessary to deliver energy to the examined sample in order to obtain significant temperature differences indicating the presence of subsurface anomalies. To detect possible defects in composite materials different methods of thermal stimulation can be applied to the tested material, these include heating lamps, lasers, eddy currents, microwaves or ultrasounds. The use of a suitable source of thermal stimulation on the test material can have a decisive influence on the detection or failure to detect defects. Non-destructive testing was carried out using the following sources of thermal stimulation, heating lamp, flash lamp, ultrasound and eddy currents. The paper presents the possibility of applying IR thermography methods for detecting defects in ballistic covers made of carbon fiber reinforced composites used in the construction of military vehicles.

Detailed heat transfer and friction factor measurements for square channel enhanced by plate insert with inclined baffles and perforated slots

An applied novel research about the development of heat transfer enhancement element using the plate insert with periodical oblique baffles and perforated slots was conducted for improving the hydrothermal performance of a heat exchanger. The infrared thermography method was adopted to detect the endwall Nusselt number distributions of a square channel enhanced by the newly devised baffle inserts with Fanning friction coefficients and thermal performance factors measured. The present baffle inserts tripped the core fluid toward channel walls and induced near-wall separated and accelerated flows to boost heat convection. The channel averaged Nusselt numbers and Fanning friction coefficients were elevated to 9–5 times of the Dittus-Boelter references and 5–85 times of the Blasius correlation levels at Reynolds numbers between 10,000 and 50,000 with the thermal performance factors in the ranges of 1.6–3.2 and 2–3.4 for forward and backward flows, which went beyond many previous types of baffle inserts. Empirical correlations permitting evaluations of average Nusselt numbers and Fanning friction coefficients with forward and backward flows were devised. Based on the thermal performance measurements, the oblique slots were preferably to be located at downstream locations of the adjacent oblique ribs for acquiring the higher hydrothermal efficiencies.

Evaluation of an ancient cast-iron Buddha head by step-heating infrared thermography

The authors report on the development of a step-heating infrared thermography method for nondestructive evaluation of a cast-iron Buddha head made in the Song Dynasty (AD 960–1279) in China. In particular, this method measures the wall-thickness distribution, which can be used as an indicator for the condition of the object. Unlike other areas of analysis, inspection of cultural relics requires special attention to safety. To avoid the heat shock associated with traditional flash thermography, a step-heating method with a mild heating process is considered to be more acceptable for evaluating cultural relics made from various materials. Before application to inspection of the Buddha head, a numerical analysis and experimental tests were performed to verify the accuracy of this step-heating thickness measurement method. Finally, thickness images of the Buddha head were acquired and analyzed. The step-heating thickness measurement method has a high accuracy and can be safely used for inspecting cultural relics.

Improved infrared thermography method for fast estimation of complex phase diagrams

Phase diagrams are a primordial tool in materials science, gathering key information for the materials synthesis and the understanding of their formation processes. Numerous experimental techniques exist to determine the phase diagram of a binary system but they are time-consuming. The previously developed IRT method (InfraRed Thermography) enabled the fast determination of preliminary phase diagrams of polyols binary systems in which only liquid-solid and eutectic transitions occur. This method thus allows accelerating their screening step which is crucial before each development of a new material. This work aims at improving the transitions detection and at adapting the IRT-method to more complex phase diagrams containing eutectic, peritectic and metatectic transitions. To do so, the phase diagram of the capric-palmitic fatty acids binary system is experimentally determined using the improved IRT-method. It is then compared with those obtained using standard Differential Scanning Calorimetry measurements (DSC) and an improved thermodynamic model. Eventually, the limiting factors and the parameters of influence such as the material droplet size, as well as the nature and roughness of the substrate are investigated and discussed.