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Lateral friction surfacing, a solid-state deposition process, is a novel friction surfacing technique. In this approach, frictional heat and plastic deformation result in deposition of consumable material from the radial surface of a tool onto a substrate. This paper presents a comprehensive assessment of lateral friction surfacing of AA2011, AA6061, and AA7075 aluminum alloys, with particular focus on the impacts of process parameters on the coating properties. The influence of process variables such as tool rotational speeds, normal applied forces, and type of consumable materials was investigated on the process temperature, physical, and metallurgical characteristics of the deposits using optical microscopy, infrared thermography, scanning electron microscopy, and EDS. This study exhibits that the lateral friction surfacing approach enables the deposition of ultra-thin and smooth layers of different aluminum alloys. Furthermore, the temperature generated in this technique was low enough to avoid plasticizing the substrate and intermixing between the consumable material and substrate, which mitigates the thermal impacts on the grain structures and metallurgical characteristics. The lateral friction surfacing performance of the different alloys can be partially explained by their material properties. High input energy provided by high normal forces and tool rotational speeds may result in failure in the deposition process of materials with lower thermal conductivity and melting point, which emphasizes on limitations for the process parameters during the process.

This research focuses on the verification of the viability of image compression in infrared thermography in order to address the problem of data storage. Specifically, images from vibrothermographic tests were utilized due to their special characteristics compared to the results from alternative infrared thermography techniques, which are able to introduce additional uncertainties to the compression process. In this research, an adaptive algorithm based on the lifting discrete wavelet transform and set-partitioning embedded blocks was used for image compression. Five different methods, namely the compression ratio, mean squared error, peak signal-to-noise ratio, structural similarity index and coordinate modal assurance criterion, were applied to evaluate the performance of the compression process while identifying and locating the regions affected more significantly after image compression. Feature extraction through the independent component analysis was then applied to the images to separate the features such as the hot spots so that the influence from the image compression process on each important feature could be evaluated independently. In this article, the theoretical background of the applied data processing techniques is firstly presented. Through two sets of data acquired from vibrothermographic tests on an aerospace-grade composite plate containing delamination, the effects of the image compression process on the relevant hot spots are evaluated, and the effectiveness of the compression process is verified. It is demonstrated that the compression process was able to reduce the size of the images significantly without adversely affecting the quality of the important features indicating the presence of damage. The major characteristics of the key features have been successfully preserved after effective image compression.

Despite tensile testing being commonly used for investigating the mechanical behavior of materials, the occurrence of heterogeneous strain and increasing temperature at high strain rates make the experiment much more complex. This work presents a method integrating synchronous full-field stereo Digital Image Correlation (DIC) and Infrared Thermography (IRT). This method enabled high resolution investigations of the development of local temperatures and strains of the specimen during tensile loading of four steels at strain rates ranging from 2.5·10−4 to 900 s−1. The tests were monitored by a stereo setup of optical cameras and an infrared camera. Data acquisition was synchronized, and a pinhole camera model was used to translate the images from all cameras to the same three-dimensional space. The displacement vector fields from DIC were subtracted from the IRT images to represent the temperature maps in a Lagrangian coordinate system. The overall thermomechanical response of the materials was shown as 3D waterfall plots, which represent localized strain and temperature as a function of position and engineering strain. The results show that temperature increased homogeneously during uniform deformation at higher strain rates (10−2-900 s−1) and increased markedly with the onset of necking on the region of localized strain. At these strain rates, the localized increase of strain and temperature during necking were observed at the same global engineering strain and position, evidencing the spatial and temporal synchronization. The described method was used to accurately investigate the evolution of localized strain and temperature in both low and high strain rate regime.

International audience; The objective of the study is to analyze the thermomechanical response of a two-dimensional monodisperse granular system made of thermoplastic polyurethane (TPU) cylinders with elliptical cross-section. Cyclic confined compression tests were performed while an infrared (IR) camera measured the temperature changes at the surface of the cylinders. Thermoelastic coupling and mechanical dissipation were distinguished in the thermal evolution. The former was mainly evidenced as a consequence of stress concentrations in the interparticle contact zones. The latter was highlighted at specific contacts, which can be explained by strong friction in these zones. The higher the number of applied mechanical cycles, the higher the temperature rise as a consequence of an accumulation of heat due to mechanical dissipation production. © 2021 Int. J. Mech. Eng. Rob. Res

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.

Waterleakage detection and localization in distribution networks pipelines is a challenge for utility companies. For this purpose, thermal Infrared Radiation (IR) techniques have been widely applied in the literature. However, the classical analysis of IR images has not been robust in detecting and locating leakage, due to presence of thermal anomalies such as shadows. In this study, to improve the detection and location accuracy, a digital image processing tool based on multitemporal IR is proposed. In multitemporal IR analysis, the variation of soil’s temperature due to field temperature can be obtained; and hence; estimating variations due to water leakage would be more accurate. An experimental setup was built to evaluate the proposed multitemporal IR water leak detection method. In order to consider the temporal temperature variation due to water leakage and mitigate the field temperature effects, a luminance transformation of the IRimages was introduced. To determine the temporal temperature variation of the soil’s surface due to the leakage, several metrics have been considered such as the difference, the ratio, the log-ratio and the coefficient variation (CV) images. Based on the experimental results, the log-ratio and the CVimages were the most robust metrics. Then, based on log-ratio or the CV image, a temporal variation image (TVI) that traduces the temporal IR luminance variation was introduced. The analysis of the TVI image showed that the CV image is less noisy than the log-ratio image, and can more accurately locate the leakage. Finally, based on TVI histogram, a threshold was defined to classify the TVI image into leakage/non-leakage areas. Results showed that the proposed method is capable of accurately detecting and locating water leakage, which is an improvement to the false detections of spatial thermal IR analysis.

International audience; An inverse method for determining the in-plane effective thermal conductivity of porous thermoplastics was implemented by coupling infrared thermography experiments and numerical simulation of heat transfer in straight fins having temperature-dependent convective heat transfer coefficient. The microstructure heterogeneity of extruded polyethylene foam, in which pores are filled with air with different levels of open and closed porosity, was taken into account. The obtained effective thermal conductivity values were compared with previous results obtained using a numerical solution based on periodic homogenization techniques (NSHT) and the transient plane source technique (TPS) to verify the accuracy of the proposed method. The results show that the suggested method is in good agreement with both NSHT and TPS. Moreover, it is also appropriate for structural materials such as unidirectional fiber-reinforced plastic composites, where heat transfer is very different according to the fiber direction (parallel or transverse to the fibers).

International audience; The main goal of this paper is the estimation of thermal resistive fields in multilayer samples using the classical front face flash method as excitation and InfRared Thermography (IRT) as a monitoring sensor. The complete inverse processing of a multilayer analytical model can be difficult due to a lack of sensitivity to certain parameters (layer thickness, depth of thermal resistance, etc.) or processing time. For these reasons, our present strategy proposes a Bayesian inference approach. Using the analytical quadrupole method, a reference model can be calculated for a set of parameters. Then, the Bayesian probabilistic method is used to determine the maximum likelihood probability between the measured data and the reference model. To keep the processing method robust and fast, an automatic selection of the calculation range is proposed. Finally, in the case of a bilayer sample, both the thickness and resistive 3D layers are estimated in less than 2 min for a space and time matrix of 50,000 pixels by 4000 time steps with a reasonable relative error of less than 5%.

Broadband mid-infrared (B-MIR) thermography using fibre optic waveguides can be critical in real-time imaging in harsh environments such as additive manufacturing, personalised medical diagnosis and therapy. We investigate the polarisation effect on thermal measurements through poly-crystalline fibre bundle employing a simple broadband cross-polarisation configuration experimental set-up. Silver halide poly-crystalline fibres AgCl1−xBrx (0 ≤ x≤1) (AgClBr-PolyC) have very wide transmission bandwidth spanning over the spectral range from 1 µm up to 31 µm FWHM. Moreover, they are non-toxic, non-hygroscopic, with relatively good flexibility, which make them very adequate for spectroscopic and thermal measurements in medical and clinical fields. In this study, we used a fibre bundle composed of seven single AgClBr-PolyC fibres, each with a core diameter of about 300 µm, inserted between two broadband MIR polarisers.A silicon carbide filament source was placed at the entrance of the fibre bundle, while a FLIR thermal camera with a close-up lens was employed to measure the spatial temperature distribution over the fibre-bundle end. Indeed, polarisation dependence of temperature measurements has been clearly observed in which the orientation of temperature extrema (minima and maxima)vary from one fibre to another within the bundle. Moreover, these observations have enabled the classification of AgClBr-PolyC fibres following their polarisation sensitivities by which some fibres are relatively highly sensitive to polarisation with polarisation temperature difference (PTD) that can reach 22.1 ± 2.8 °C, whereas some others show very low PTD values down to 3.1 ± 2.8 °C. Many applications can readily be found based on the advantages of both extreme cases. © 2020, The Author(s). SM, AM, CS, JB and SAMT acknowledge European Commission Erasmus International Credit Mobility 2015–2020 between Ural Federal University named after the frst President of Russia B.N. Yeltsin, Yekaterinburg, Russia, and University of Limerick, Ireland, as well as Erasmus Bilateral Exchange between Wroclaw University of Science and Technology, Poland, and University of Limerick, Ireland, 2010–2020 for funding the work on imaging, characterisation and application development using MIR bundle fbres in medicine and manufacturing. JB acknowledges European Commission Erasmus+KA107 Inter-institutional Student and Staf Mobility Programme 2018–2020 between Wroclaw University of Science and Technology, Poland, and Ural Federal University, Yekaterinburg, Russia. SM and AM acknowledges Science Foundation Ireland (SFI) Centre for Medical Devices co-funded under the European Regional Development Fund (Grant Number 13/RC/2073) for characterising bundle fbre. EK, AK and LZ acknowledge Grant No. 18-73-10063 from the Russian Science Foundation for funding the fabrication of fbre bundles.

This research focuses on the development of a damage detection algorithm based on modal testing, vibrothermography, and feature extraction. The theoretical development of mathematical models is presented to illustrate the principles supporting the associated algorithms, through which the importance of the three components contributing to this approach is demonstrated. Experimental tests and analytical simulations have been performed in laboratory conditions to show that the proposed damage detection algorithm is able to detect, locate, and extract the features generated due to the presence of sub-surface damage in aerospace grade composite materials captured by an infrared camera. Through tests and analyses, the reliability and repeatability of this damage detection algorithm are verified. In the concluding observations of this article, suggestions are proposed for this algorithm’s practical applications in an operational environment.

International audience; Mechanical seals are composed of two annular flat rings in contact and relative motion to ensure sealing of a rotating shaft. Because of friction in the sealing interface, a significant temperature rise can be experienced in the contact. Two decades ago, it has been shown that creating a network of shallow dimples on one sealing surface can help to create a lubricant film in the interface and thus reduce friction. Since then, many research works have been carried out on the socalled surface texturing, showing the interest of surface modification for mechanical seals. In the present work, several surface patterns, defined by numerical simulations and machined by plasma etching on stainless steel rings were tested. The rings were mounted on a test bench in which they slide against a sapphire disk counter face. This disk is transparent to infrared radiation and allows interface temperature measurements by infrared thermography. It is shown that all the tested surface texture patterns exhibit a temperature rise at least 2 times lower than with flat smooth surfaces. A slight difference between the different dimple shapes is obtained indicating that the temperature and friction are more controlled by texture area and surface roughness rather than by the texture pattern.

Recently, a technique for rapidly determining a material’s fatigue limit by measuring energy dissipation using infrared thermography has received increasing interest. Measuring the energy dissipation of a material under fatigue loading allows the rapid determination of a stress level that empirically coincides with its fatigue limit. To clarify the physical implications of the rapid fatigue limit determination, the relationship between energy dissipation and fatigue damage initiation process was investigated. To discuss the fatigue damage initiation process at grain size scale, we performed high-spatial-resolution dissipated energy measurements on type 316L austenitic stainless steel, and observed the slip bands on the same side of the specimen. The preprocessing of dissipated energy measurement such as motion compensation and a smoothing filter was applied. It was found that the distribution of dissipated energy obtained by improved spatial resolution measurement pinpointed the location of fatigue crack initiation. Owing to the positive correlation between the magnitude of dissipated energy and number of slip bands, it was suggested that the dissipated energy was associated with the behavior of slip bands, with regions of high dissipated energy predicting the location of fatigue crack initiation.

The aim of this paper was to evaluate the surface temperature distribution in several single and double jersey weft-knitted fabrics. Plain knitted fabrics as well as those with, double cross-tuck, cross-tuck, double cross-miss, and cross-miss pattern together with plain rib and interlock structures were under consideration in term of their structural differences. In order to investigate the temperature distribution in produced samples, all the fabrics were placed on a 35?C adjusted hot plate instrument and thermal images were captured by an infrared thermal camera. The results revealed that the presence of tuck stitches in single jersey weft-knitted fabrics increase the air permeability due to the increasing the fabrics? porosity, which in turn leads to decrease their thermal resistance as compared with plain knitted structure. On the other hand, addition of miss stitches in single jersey knitted structures would decrease the thickness of fabrics and improves their heat transfer ability. The obtained results, from rib and interlock knitted structures, suggested their lower heat conductivity in comparison to the single jersey knitted samples.

International audience; The present paper provides the first full thermo-mechanical characterization of a crystallizing filled natural rubber under uniaxial and biaxial loadings. During the mechanical tests, the temperature was measured by using infrared thermography and processed by means of the heat diffusion equation for determining the corresponding heat power density. The intrinsic dissipation due to viscosity and stress softening are evaluated under cyclic loading by the energy balance. Energy contributions to the hysteresis loop converted into heat and stored in the material are distinguished. The heat power density is also used to evaluate the strain-induced crystallinity. This analysis provides new results on the energetic behavior of filled natural rubber. Accordingly, crystallization takes place under high biaxiality levels, close to the equibiaxial loading condition, while multiaxiality influences the crystallization onset. These experimental results are used in the second part of the present paper for a physically based modeling of the complex behavior of filled natural rubbers.

Conservation of artworks is of paramount importance nowadays around the world. Clever conservation by using non-destructive testing techniques is highly appreciated by restorers and art historians. Among these, active infrared thermography needs the use of numerical simulations concerning the heat transfer from the heat source into the target. This, in order to gently heat the precious surface by avoiding any type of damage, such as colour changes and/or shrinkage and warpage effects, therefore, the understanding of the nature of the pigments, as well as the mapping of the support and eventual foreign materials is of primary importance in the survey. It is possible to accomplish these tasks by applying, e.g. X-Ray Fluorescence spectroscopy and radiography (X-Ray), respectively. Here, the latter techniques have been used on an ancient marquetry sample. Consequently, a thermographic inspection was performed, while a thermal–numerical simulation was implemented in ANSYS® environment. Numerical simulations were able to visualize some types of defects by calibrating the thermal inspection based on a comparison among defective and sound areas. Results demonstrated how such an integrated method is useful to provide robust information without damage to the work of art under restoration.

This work is centred on an ancient Italian church. Since 2011, a restoration plan has been undertaken by following sequential phases. The methodological approach to restoration was guided by environmental monitoring campaigns. In particular, two thermo-hygrometric campaigns were carried out during the warm months of the years 2015 and 2016. The first set of measurements was executed during the restoration of facades and roofs, making it possible to reach even areas that are usually difficult to access. The second set was performed to evaluate the indoor thermo-hygrometric conditions following the work of the previous year. This was intended to assess their differences in variability, the influence of the outdoor environment and any real and perceived improvement. Results demonstrate that thermal images helped in identifying both the heat sources causing thermal discomforts and the good thermal capacity of masonries. Concerning the heat index (HI), the church showed an improvement in the trend of malaise perceived by people during the second summer period (∼2°C lower than 2015). Finally, in the last microclimate monitoring, the roof structure no longer acted as an amplifier for daily temperature excursions.

An experimental investigation on the flow topology over a rotor operating atlow Reynolds numbers is presented. The feasibility of laminar to turbulenttransition experiments over small rotors is demonstrated. Phase-locked infraredthermography coupled with simultaneous force and torque measurements wereused to study a three bladed rotor with a NACA0012 aerofoil section set at auniform angle of incidence of 10◦. Boundary layer transition was forced usingtwo-dimensional (2D) and three-dimensional (3D) roughness elements, placedat approximately 5% and 28% of the rotor blades chord. In the 3D roughnessconfigurations once the critical roughness Reynolds was attained the streaksdownstream developed into fully turbulent wedges. For the current rotor con-figuration, it was found that the state of the boundary layer can significantlyaffect its performance, with the non-optimal forcing of laminar to turbulenttransition generally resulting in a loss of performance when compared to thesmooth reference rotor case.Keywords:Infrared Thermography; Boundary layer transition; Low Reynoldsnumber; rotor

Composite materials are becoming more popular in technological applications due to the significant weight savings and strength offered by these materials compared to metallic materials. In many of these practical situations, the structures suffer from drop-impact loads. Materials and structures significantly change their behavior when submitted to impact loading conditions compared to quasi-static loading. The present work is devoted to investigating the thermal process in carbon-fiber-reinforced polymers (CFRP) subjected to a drop test. A novel drop-weight impact test experiment is performed to evaluate parameters specific to 3D composite materials. A strain gauge rosette and infrared thermography are employed to record the kinematic and thermal fields on the composites&rsquo, surfaces. This technique is nondestructive and offers an extensive full-field investigation of a material&rsquo, s response. The combination of strain and infrared thermography data allows a comprehensive analysis of thermoelastic effects in CFRP when subjected to impacts. The experimental results are validated using numerical analysis by developing a MATLAB&reg, code to analyze whether the coupled heat and wave equation phenomenon exists in a two-dimensional polar coordinate system by discretizing through a forward-time central-space (FTCS) finite-difference method (FDM). The results show the coupling has no significant impact as the waves generated due to impact disappears in 0.015 s. In contrast, heat diffusion happens for over a one-second period. This study demonstrates that the heat equation alone governs the CFRP heat flow process, and the thermoelastic effect is negligible for the specific drop-weight impact load.

Lien pour fichier : https://oskar-bordeaux.fr/handle/20.500.12278/124281; International audience; An emerging dynamic calorimetry method based on infrared thermography (IRT method) has recently proven to be of great interest for the fast establishment of the phase diagrams of binary systems of organic materials (sugar alcohols, fatty acids, fatty alcohols). The methods allowed for their determination in a single 2-h experiment when standard techniques require weeks of measurements hence enabling a significant improvement of the efficiency of material screening processes. As adding a component to the system greatly increases the number of compositions to be studied (21 for binary, 231 for ternary assuming a 5 mol% increment between compositions), the IRT method may be of even greater use with increasing system complexity. This work then aims at studying the applicability of IRT for the fast establishment of phase diagrams of ternary systems with the lauric (LA), myristic (MA), and palmitic (PA) fatty acids ternary system as an illustrative case. A phase diagram in agreement with the results of the literature and with DSC measurements is established using IRT in a few hours-experiments instead of weeks to months with standard methods. The obtained results (e.g.67 mol%LA + 23 mol%MA + 10 mol%PA for the eutectic composition, occurrence of a ternary eutectic reaction at 32 °C) are promising. This technique also successfully allows for rapid exploration of the phase diagram: reconstruction of the liquidus surface, identification of the eutectic transition, 4-phase equilibrium. IRT is a particularly interesting high-throughput characterization method for the establishment of the phase diagrams of ternary (or higher-order) systems.

International audience; An experimental investigation was performed to determine the local value of heat transfer coefficient with a free-surface axisymmetric downward jet of lubricating oil impinging on a fixed plate. A large range of Prandtl numbers was considered (148 < < 925) in order to fill a data gap on highly viscous fluids, especially regarding local measurements. In the range of Reynolds numbers considered (170 < < 2225), dependencies similar to the literature were identified for laminar and turbulent regimes. A significant influence of the injector diameter (1, 2 and 4 mm) on exchanges was found, but nozzle-to-target distances (5 < / < 20) showed no particular effect. Local and mean values of the Nusselt number were correlated by taking into account the above-mentioned parameters. Nevertheless, data exploitation showed that the warming of the thin liquid film over the plate, which is dependent on the heating flux to evacuate, should be taken into account for viscous fluids such as oils; the induced changes of viscosity lead to divergencies in measured heat exchanges. A methodology based on empirical observation was developed to take this phenomenon into consideration.

Extraction of raw materials, especially in extremely harsh underground mine conditions, is irrevocably associated with high risk and probability of accidents. Natural hazards, the use of heavy-duty machines, and other technologies, even if all perfectly organized, may result in an accident. In such critical situations, rescue actions may require advanced technologies as autonomous mobile robot, various sensory system including gas detector, infrared thermography, image acquisition, advanced analytics, etc. In the paper, we describe several scenarios related to rescue action in underground mines with the assumption that searching for sufferers should be done considering potential hazards such as seismic, gas, high temperature, etc. Thus, possibilities of rescue team activities in such areas may be highly risky. This work reports the results of testing of a UGV robotic system in an underground mine developed in the frame of the AMICOS project. The system consists of UGV with a sensory system and image processing module that are based on an adaptation of You Only Look Once (YOLO) and Histogram of Oriented Gradients (HOG) algorithms. The experiment was very successful; human detection efficiency was very promising. Future work will be related to test the AMICOS technology in deep copper ore mines.

The growing importance of reliable, rapid, and non-contact non-destructive evaluation (NDE) of parts/structures either during manufacturing or maintenance operations has promoted the development of real-time, automated, and in-situ methods. The major driving factors for automation of traditional NDE techniques, such as thermographic imaging methods, are savings in cost and time. In this work a novel real-time low-cost automated heating and cooling thermographic system is developed. The system implements a novel cooling mechanism along with heating elements to provide precise control of heating and cooling of inspected structures and was built using low-cost components. A carbon fibre reinforced plastic (CFRP) composite sample with flat bottom holes (FBH) was used to evaluate the effectiveness of the system. This system is coupled with a model to provide insights into system optimisation and show the potential that highly flexible inspection systems can be tailored for specific industrial requirements. The modelled heating and cooling process was important in determining which parts of the thermal profile would provide the best results. The system was assessed using three heating/cooling profiles: heating only (HO), cooling only (CO) and heating and cooling (HC). The results show that each method was equally as good as determining defects in the tested structure, with HC having the potential to outperform the others if optimised.

This work is devoted to the experimental investigation of the effect of laser shock peening (LSP) on the thermo-mechanical properties of metals. ARMCO iron was chosen as the model material for the study. Samples were subjected to LSP, and were tested following the procedure of the self-heating (Risitano) technique. To investigate the damage that was induced by heating, the fatigue tests were coupled with infrared thermography measurements. The results of the study showed that the LSP procedure qualitatively changes the temperature evolution in ARMCO iron during cyclic loading. The heating (energy dissipation) of the LSP treated specimen was several times higher than that of the specimen in the initial state. To explain the structural mechanisms of energy dissipation, the microstructure of the specimens was examined using transmission (TEM) and scanning (SEM) electron microscopy, as well as electron backscattering diffraction (EBSD). The results of the structural investigation confirm the qualitative change of defect evolution caused by LSP treatment.

A current trend in mechanical testing technologies is to equip researchers and industrial practitioners with the facilities for non-destructive characterisation of the deformation and fracture processes occurring on different scales. The synergistic effect of such a combination of destructive and non-destructive techniques both widens and deepens existing knowledge in the field of plasticity and fracture of materials and provides the feedback sought to develop new non-destructive testing approaches and in situ monitoring techniques with enhanced reliability, accuracy and a wider scope of applications. The macroscopic standardised mechanical testing is still dominant in the research laboratories and industrial sector worldwide. The present paper reviews multiple challenges commonly faced by experimentalists, aiming at enhancing the capability of conventional mechanical testing by a combination of contemporary infrared thermography (IRT), rapid video imaging (RVI) with non-contact strain mapping possibilities enabled by the digital image correlation (DIC) method, and the acoustic emission (AE) technique providing unbeatable temporal resolution of the stochastic defect dynamics under load. Practical recommendations to address these challenges are outlined. A versatile experimental setup uniting the unique competencies of all named techniques is described alone with the fascinating possibilities it offers for the comprehensive characterisation of damage accumulation during plastic deformation and fracture of materials. The developed toolbox comprising practical hardware and software solutions brings together measuring technologies, data, and processing in a single place. The proposed methodology focuses on the characterisation of the thermodynamics, kinematics and dynamics of the deformation and fracture processes occurring on different spatial and temporal scales. The capacity of the proposed combination is illustrated using preliminary results on the tensile and fatigue behaviour of the fcc Inconel-625 alloy used as a representative example. Dissipative processes occurring in this alloy are assessed through the complex interplay between the released heat, acoustic emission waves, and expended and stored elastic energy.

Additive manufacturing (AM) of metals and in particular laser powder bed fusion (LPBF) enables a degree of freedom in design unparalleled by conventional subtractive methods. To ensure that the designed precision is matched by the produced LPBF parts, a full understanding of the interaction between the laser and the feedstock powder is needed. It has been shown that the laser also melts subjacent layers of material underneath. This effect plays a key role when designing small cavities or overhanging structures, because, in these cases, the material underneath is feed-stock powder. In this study, we quantify the extension of the melt pool during laser illumination of powder layers and the defect spatial distribution in a cylindrical specimen. During the LPBF process, several layers were intentionally not exposed to the laser beam at various locations, while the build process was monitored by thermography and optical tomography. The cylinder was finally scanned by X-ray computed tomography (XCT). To correlate the positions of the unmolten layers in the part, a staircase was manufactured around the cylinder for easier registration. The results show that healing among layers occurs if a scan strategy is applied, where the orientation of the hatches is changed for each subsequent layer. They also show that small pores and surface roughness of solidified material below a thick layer of unmolten material (&gt, 200 µm) serve as seeding points for larger voids. The orientation of the first two layers fully exposed after a thick layer of unmolten powder shapes the orientation of these voids, created by a lack of fusion.

International audience; Detailed knowledge of the behaviour of rocks under thermal stress is essential in a variety of fields such as the exploitation of oil and mineral resources, the geothermal sector, the storage of radioactive liquid waste, or even CO2 capture and storage.Granites are widely studied and exploited in these fields, and they show different reactions to high-temperature and thermal cycles due mainly to their high mineralogical and textural heterogeneity. One of the features that influences the most the thermal response is the porosity.The objective of this study is to evaluate the influence of porosity when these rocks are exposed to different thermal treatments. For that purpose, experiments were carried out on four granitoids selected by their similar crystal size, but with variable mineral proportion and porosity values, ranging from 1 to 6%. Two kinds of tests were performed: i) progressive heating cycles from 90 °C to 130 °C to determine the critical threshold for thermal damage; ii) thermal fatigue with cycles of heating-cooling up to 200 °C.The porosity and the water transport phenomena of the samples were characterised before and after each cycle by the monitoring of capillary water uptake coupled with infrared thermography. This technique allowed to follow the capillary fringe migration during the test and the evolution of the cooling rate index. The direct assessment of the damage was carried out by mercury injection porosimetry, optical polarising microscopy, and scanning electron microscopy.The combination of all the results permitted to establish a link between the evolution of temperature and the modification of porous networks in granitoids. Microcracks appeared distinctly at a temperature between 90 °C to 130 °C for high porosity granitoids whose Quartz/Feldspar ratio was close to 1. For higher temperatures, the low porosity granitoids develop microcracks from the first heating cycle. The porosity then showed a stronger impact on thermal behaviour than the effect of the mineralogy. The results obtained from infrared thermography allowed to detect the strong variations in the microstructure.

In order to improve predictions of the on-ground casualty risk associated with the uncontrolled atmospheric re-entry of satellites from Low Earth Orbit, there is significant research interest in the development of engineering models of hypersonic heating rates to faceted shapes. A key part of developing such models is generating accurate datasets of the heat fluxes experienced by faceted shapes at various orientations in hypersonic flows. In this work, we use wind tunnel experiments and CFD simulations to study the hypersonic flow around a cuboid geometry at 5 ° incidence in a Mach 5 flow at Reynolds numbers of 79.5 × 10 3 , 109 × 10 3 and 148 × 10 3 . The wind tunnel data are obtained in the University of Manchester's High SuperSonic Tunnel and consist of schlieren images and temperature histories collected using infrared thermography. These temperature histories are used to calculate experimental heat fluxes by solving a three-dimensional inverse heat conduction problem. CFD simulations around the same geometry at equivalent free-stream conditions are calculated with the DLR-TAU code. The experimental and CFD results show good agreement both in terms of heat fluxes as well as flow structure. Notable flow structures include wedge-shaped regions of high heat flux which emanate from the windward corners of the cube. Analysis of numerical Q-criterion contours show that these high heat flux regions are caused by vortex structures generated by the expansion at the cube corner. Analysis of the numerical skin friction coefficient shows that even at incidence there is no breakaway separation from the expansion edges of the cube and the flow remains attached throughout. We show that although there is little change in the average heat flux experienced by a cube at 5 ° incidence to the free-stream compared to one at 0 ° incidence, there are significant changes in the heat flux contours over the cubes at these two incidences. Finally, we calculate a number of heating shape factors which can easily be implemented in satellite re-entry and demise prediction analysis tools.

The problem studied in this paper is the possibility of applying a non-invasive technique in monitoring respiratory rate in premature infants. At this time the systems used to monitor respiration in the newborn are difficult to use and do not provide satisfactory results. This paper proposes the use of thermographic technique and the analysis of thermal images that could be used to monitor the respiratory rate of premature infants. The thermographic technique was chosen because it is a non-invasive technique. In this case, monitoring is based on the determination of temperature changes in the nostrils caused by breathing (inhale/exhale). Video images focused on the region of the nostrils, with duration of 1 min, were used in processing at different times, from which the rate of inspiration/expiration was extracted starting from the temperature variations. Following the results obtained, we believe that IR thermography it is a technique that can be integrated into a complex system that can be used to monitor the respiratory rate of the newborn.

A calorimetry method based on infrared thermography is showing promise for material screening, allowing the simultaneous detection of phase transitions of multiple samples at a time, hence enabling the establishment of phase diagrams in a record time. The working principle of this method is similar to the one of Differential Thermal Analysis. Therefore, this work aims at identifying if the melting enthalpy of materials could be estimated on the same basis using infrared thermography. In this work, the melting of six eutectic mixtures of fatty acids is estimated under three considerations. The results are compared to Differential Scanning Calorimetry measurements and literature data. The accuracy of the method is discussed and improvements are proposed.

We present an optical technique that combines simultaneous planar laser-induced fluorescence (PLIF), particle tracking velocimetry (PTV) and infrared (IR) thermography for the space-and time-resolved measurement of the film-height, 2-D velocity and 2-D free-surface temperature in liquid films falling over an inclined, resistively-heated glass substrate. Using this information and knowledge of the wall temperature, local and instantaneous heat-transfer coefficients (HTCs) and Nusselt numbers, Nu, are also recovered along the waves of liquid films with Kapitza number, Ka = 180 , and Prandtl number, Pr = 77 . By employing this technique, falling-film flows are investigated with Reynolds numbers in the range Re = 18–66, wave frequencies set to f w = 7 , 12 and 17 Hz, and a wall heat flux set to q = 2.5 W cm−2. Complementary data are also collected in equivalent (i.e., for the same mean-flow Re) flows with q = 0 W cm−2. Quality assurance experiments are performed that reveal deviations of up to 2–3% between PLIF/PTV-derived film heights, interfacial/bulk velocities and flow rates, and both analytical predictions and direct measurements of flat films over a range of conditions, while IR-based temperature measurements fall within 1 °C of thermocouple measurements. Highly localized film height, velocity, flow-rate and interface-temperature data are generated along the examined wave topologies by phase/wave locked averaging. The application of a heat flux ( q = 2.5 W cm−2) results in a pronounced “thinning” of the investigated films (by 18%, on average), while the mean bulk velocities compensate by increasing by a similar extent to conserve the imposed flow rate. The axial-velocity profiles that are obtained in the heated cases are parabolic but “fuller” compared to equivalent isothermal flows, excluding any wave-regions where the interface slopes are high. As the Re is reduced, the heating applied at the wall penetrates through the film, resulting in a pronounced coupling between the HTC and the film height in thinner film regions. When the imposed wave frequency is increased, a narrower range of HTCs is observed, which we link to the evolution of the film topology and the associated redistribution of the fluid flow upstream of the imaging location, as the liquid viscosity decreases. The local and instantaneous Nu is strongly coupled to the film height and experiences variations that increase as f w is reduced.

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. The viability of using off-chip single-shot imaging techniques for local thermal testing in integrated Radio Frequency (RF) power amplifiers (PA’s) is analyzed. With this approach, the frequency response of the output power and power gain of a Class A RF PA is measured, also deriving information about the intrinsic operation of its transistors. To carry out this case study, the PA is heterodynally driven, and its electrical behavior is down converted into a lower frequency thermal field acquirable with an InfraRed Lock-In Thermography (IR-LIT) system. After discussing the theory, the feasibility of the proposed approach is demonstrated and assessed with thermal sensors monolithically integrated in the PA. As crucial advantages to RF-testing, this local approach is noninvasive and demands less complex instrumentation than the mainstream commercially available solutions.

This study deals with tensile tests on rigid polymeric innovative material for greenhouse covering. Specimens of polycarbonate Makrolon® UV Climate Control blue were analyzed. Tension tests were conducted on bone-shaped samples, according to European standards, and at different temperatures from 20 °C to 80 °C on the basis of the summer temperatures registered by the greenhouses supporting metal structures in contact with the plastic covering. During tensile test the surface temperature of the specimens was measured using infrared technology. Finally, the obtained strain and temperature trend are discussed and an interpretation of the mechanical behaviour of the material is given based on a Griffith like approach.

The influence of types and parameters of hollow microspheres in the composition of syntactic foams on their structure and coefficient of thermal conductivity has been studied. By using structural and thermal analysis it has been found that the volume concentration and the size of the ceramic and glass hollow microspheres have a strong impact on the density and thermophysical properties of the thin syntactic foams coatings. It has been shown that the best heat insulating properties belong to syntactic foam with composition of 60 vol. % ceramic microspheres with particle size of 1 - 40 μm (k = 0.029 W/m·K, R = 0.008 (m2·K)/W) and with composition of 80 vol. % glass hollow microspheres with particle size of 9 - 25 μm (k = 0.087 W/m·K, R = 0.008 (m2·K)/W). The results demonstrate that application of syntactic foams as thin insulating coatings is appropriate and they are an energy efficient material with number of benefits compare with the common thermal insulators.

This paper aims at reporting on the most recent outcomes of an innovative potential laboratory test (IRTest), which allows the indirect estimation of porosity of intact rock specimens through InfraRed Thermography . Starting from the positive preliminary available literature data, proving the existence of a relation between the cooling of previously heated rocks and their porosity, in this paper five different rock types, with a variable porosity grade (ranging from 40%), were tested according to an innovative procedure. After an initial heating phase, their cooling was monitored through InfraRed Thermography and the Cooling Rate Index (CRI) was calculated to describe their attitude during the heat dissipation. Such index proved well correlated to the porosity of tested specimens , which was preliminary calculated according to international standards. Achieved outcomes demonstrate that the cooling trend of rocks within the first 10 min of test (CRI 10) represents a reliable index for the indirect quantification of such important physical parameter, thus proposing a wide range of ideas for further scientific researches aiming at implementing and validating the scientific casuistry on this new topic.

Non-destructive tests have been increasingly used in historic buildings not only for pre-restoration investigation but also as useful tools to evaluate the effectiveness of eventual interventions. These tests can complement and supplement destructive tests like laboratory analysis of extracted samples as long as a sound sampling plan has been put in place to commensurate with the pattern and extent of dilapidation and materials distribution. Common methods employed in projects in Singapore and Malaysia include the infrared thermography, ground penetrating radar, microwave moisture tomography and ultrasonic pulse echo tomography. The paper discusses about a selection of case studies, demonstrating the application of various techniques for the identification of hidden details, defects and deterioration, and moisture detection.

Structural S355 steel is widely applied in various sectors. Fatigue properties are of fundamental importance and extremely time consuming to be assessed. The aim of this research activity is to apply the Static Thermographic Method during tensile tests and correlate the temperature trend to the fatigue properties of the same steel. The Digital Image Correlation (DIC) and Infrared Thermography (IR) techniques have been used during all static tests. The Digital Image Correlation technique allowed the detection of displacements and strain, and so the evaluation of the mechanical properties of the material. Traditional fatigue tests were also performed in order to evaluate the stress-number of cycles to failure curve of the same steel. The value of the fatigue limit, obtained by the traditional procedure, was compared with the values predicted by means of the Static Thermographic Method (STM) obtained from tensile tests. The predicted values are in good agreement with the experimental values of fatigue life.

Steel bottles, most commonly used by scuba divers, are prone to rust and need to be maintained properly and preventively examined during usage. Due to the geometrical characteristics of the tank (rounded wall) and the inaccessible inner surface of the wall where corrosion damages and initial cracks are expected to be found, the conventional nondestructive techniques do not yield usable results. Herein, emphasis is placed on non-destructive testing (NDT) by means of infrared thermography. The Pulse Phase Thermography (PPT) has been used for composite polymer matrix materials, but with the development of IR cameras, the method has found its application even for NDT of thin metal plates. In this paper, the Fast Fourier Transform (FFT) of infrared images is applied on severely corroded scuba divers tank. The amplitude and phase images contain information on damages or/and other structures inside the inspected part as these lead to a shift in the amplitude and phase of heat waves. In damaged areas heat wave passes shorter path due to differences in the thickness of the metal wall resulting in different heating/cooling curves. As a result, heat waves have different phase delay and defects can be seen as different color zones on phase images in characteristic pit corrosion oval shape.

The rotating machinery plays a vital role in industrial systems, in which unexpected mechanical faults during operation can lead to severe consequences. For fault prevention, many fault diagnostic methods based on vibration signals are available in the literature. However, the vibration signals are obtained by using different types of sensors, which can cause sensor installation issues and damage the rotating machinery. In addition, this kind of data acquisition through vibration signal induces a large amount of signal noise during machine operation, which will challenge the later fault diagnosis. A recent fault detection method based on infrared thermography (IRT) for rotating machinery avoids these issues. However, the corresponding literature is limited by the fact that the characteristics of the manual design cannot characterize the fault completely so that the diagnostic accuracy cannot exceed the diagnostic method based on the vibration signals. This paper introduces a popular image feature extraction method into the fault diagnosis of rotating machinery based on IRT for the first time. First, capturing the IRT images of the rotating machinery in different states, and then two popular feature extraction methods for IRT images, bag-of-visual-word, and convolutional neural network, are tested in turn. Finally, the extracted features are classified to implement the automatic fault diagnosis. The developed method is applied to analyze the experimental IRT images collected from bearings, and the results demonstrate that the developed method is more effective than the traditional methods based on vibration signals.

So far, there have been many types of researches subject to technical requirements due to image registration. Using image registration can lower deviation from sequential images and make it possible to analyze the information variation of the particular area subsequently. This study provides a procedure creating fixed image based on the data of facial IR thermography, where its methods include the visual saliency map by detected image, as well as cluster algorithm. Comparison is also made here to solve the merits and demerits by affine parameter to reach the optimum measure among Genetic Algorithm, Particle Swarm Optimization, and Simulated Annealing Algorithm, where there are two control parameters concerning this experiment: one is the calculation of time confined each alignment, while the other one is to use parallel computing toolbox or not. The optimum method will be chosen by the values of the objective function based on the control parameters. Afterward, the optimal internal parameter is to be verified through the Taguchi experiment and the validity of this procedure in this study will be built following the parameter result as above. Therefore, the difference of images before and after alignment can be validated by overlapping the images before and after alignment as well as the image quality measurements, where its results reveal that the alignment procedure of IR thermography in this study is capable of performing human face alignment precisely, and subsequently, do help data statistics and analysis concerning temperature area interdependence.

A change in plantar temperature distribution can be an indicator of tissue damage, inflammation, or peripheral vascular abnormalities associated with diabetic foot. Despite the efforts to detect these abnormalities through infrared thermography, there are still several problems to be addressed, especially to detect abnormalities on each foot separately. In this paper, a characterization of the plantar temperature distribution based on a probabilistic approach is proposed. The objective is to detect temperature variations on each foot eluding contralateral comparison. A beta mixture model with four components approximates the plantar temperature distributions of diabetic and non-diabetic subjects. Each component represents an area of the plantar region: toes; metatarsal heads; arch; and heel. The approximation was applied to 60 temperature distributions of non-diabetic subjects and 220 of diabetic subjects. The results suggest that it is possible to characterize distribution in terms of the mean of its beta components.

The demand for composite fiber material is significantly high due to its excellent mechanical properties and its use in various industries. Recently, with the increasing awareness of environmental issues, researchers are now focusing more on eco-friendly and green materials. A biocomposite offers a good balance of strength and stiffness ratio, bending and membrane mechanical properties, balanced thermal distortion stability, reduced weight and cost, improved fatigue resistance, reduced notch sensitivity, and, comparatively, better performance than synthetic composites. Yet, due to the complex anisotropy of the composite material, the inspection and detection of inner defects become a challenge. Long-pulse thermography is one of the non-destructive evaluations (NDEs) used to detect defects in composite materials. However, very limited research has been carried out on the usage of a low-resolution infrared camera to perform defect or damage inspection on flax composite laminates. In this paper, an experimental setup of a long pulse thermography system using low-resolution infrared camera was performed on flax bio-composite to identify impact and lightning damage. The result highlights that with control parameters, a low-resolution infrared camera has the capability to capture the lightning and impact defects of flax biocomposites using the long-pulse thermography system. An image processing method is then applied to the defect to improve the quality of defect detection and reduce background noise.

The safety of electric power networks depends on the health of the transformer. However, once a variety of transformer failure occurs, it will not only reduce the reliability of the power system but also cause major accidents and huge economic losses. Until now, many diagnosis methods have been proposed to monitor the operation of the transformer. Most of these methods cannot be detected and diagnosed online and are prone to noise interference and high maintenance cost that will cause obstacles to the real-time monitoring system of the transformer. This paper presents a full-time online fault monitoring system for cast-resin transformer and proposes an overheating fault diagnosis method based on infrared thermography (IRT) images. First, the normal and fault IRT images of the cast-resin transformer are collected by the proposed thermal camera monitoring system. Next is the model training for the Wasserstein Autoencoder Reconstruction (WAR) model and the Differential Image Classification (DIC) model. The differential image can be acquired by the calculation of pixel-wise absolute difference between real images and regenerated images. Finally, in the test phase, the well-trained WAR and DIC models are connected in series to form a module for fault diagnosis. Compared with the existing deep learning algorithms, the experimental results demonstrate the great advantages of the proposed model, which can obtain the comprehensive performance with lightweight, small storage size, rapid inference time and adequate diagnostic accuracy.

One of the concerns about the use of passive Infrared Thermography (IRT) for structural health monitoring (SHM) is the determination of a favorable period to conduct the inspections. This paper investigates the use of numerical simulations to find appropriate periods for IRT-based detection of subsurface damages in concrete bridge slabs under passive heating along a 1 year of time span. A model was built using the Finite Element Method (FEM) and calibrated using the results of a set of thermographic field inspections on a concrete slab sample. The results showed that the numerical simulation properly reproduced the experimental thermographic measurements of the concrete structure under passive heating, allowing the analysis to be extended for a longer testing period. The long-term FEM results demonstrated that the months of spring and summer are the most suitable for passive IRT inspections in this study, with around 17% more detections compared to the autumn and winter periods in Brazil. By enhancing the possibility of using FEM beyond the design stage, we demonstrate that this computation tool can provide support to long-term SHM.

In this paper the mathematical and physical correlation between fundamental thermophysical properties of materials, with their structure, for nanofluid thermal performance in spray cooling applications is presented. The present work aims at clarifying the nanofluid characteristics, especially the geometry of their nanoparticles, leading to heat transfer enhancement at low particle concentration. The base fluid considered is distilled water with the surfactant cetyltrimethylammonium bromide (CTAB). Alumina and silver are used as nanoparticles. A systematic analysis addresses the effect of nanoparticles concentration and shape in spray hydrodynamics and heat transfer. Spray dynamics is mainly characterized using phase Doppler interferometry. Then, an extensive processing procedure is performed to thermal and spacetime symmetry images obtained with a high-speed thermographic camera to analyze the spray impact on a heated, smooth stainless-steel foil. There is some effect on the nanoparticles’ shape, which is nevertheless minor when compared to the effect of the nanoparticles concentration and to the change in the fluid properties caused by the addition of the surfactant. Hence, increasing the nanoparticles concentration results in lower surface temperatures and high removed heat fluxes. In terms of the effect of the resulting thermophysical properties, increasing the nanofluids concentration resulted in the increase in the thermal conductivity and dynamic viscosity of the nanofluids, which in turn led to a decrease in the heat transfer coefficients. On the other hand, nanofluids specific heat capacity is increased which correlates positively with the spray cooling capacity. The analysis of the parameters that determine the structure, evolution, physics and both spatial and temporal symmetry of the spray is interesting and fundamental to shed light to the fact that only knowledge based in experimental data can guarantee a correct setting of the model numbers.

Finding efficient and less expensive techniques for different aspects of culvert inspection is in great demand. This study assesses the potential of infrared thermography (IRT) to detect the presence of cavities in the soil around a culvert, specifically for cavities adjacent to the pipe of galvanized culverts. To identify cavities, we analyze thermograms, generated via long pulse thermography, using absolute thermal contrast, principal components thermography, and a statistical approach along with a combination of different pre- and post-processing algorithms. Using several experiments, we evaluate the performance of IRT for accomplishing the given task. Empirical results show a promising future for the application of this approach in culvert inspection. The size and location of cavities are among the aspects that can be extracted from analyzing thermograms. The key finding of this research is that the proposed approach can provide useful information about a certain type of problem around a culvert pipe which may indicate the early stage of the cavity formation. Becoming aware of this process in earlier stages will certainly help to prevent any costly incidents later.

Infrared thermography is a growing technology in the engineering geological field both for the remote survey of rock masses and as a laboratory tool for the non-destructive characterization of intact rock. In this latter case, its utility can be found either from a qualitative point of view, highlighting thermal contrasts on the rock surface, or from a quantitative point of view, involving the study of the surface temperature variations. Since the surface temperature of an object is proportional to its emissivity, the knowledge of this last value is crucial for the correct calibration of the instrument and for the achievement of reliable thermal outcomes. Although rock emissivity can be measured according to specific procedures, there is not always the time or possibility to carry out such measurements. Therefore, referring to reliable literature values is useful. In this frame, this paper aims at providing reference emissivity values belonging to 15 rock types among sedimentary, igneous and metamorphic categories, which underwent laboratory emissivity estimation by employing a high-sensitivity thermal camera. The results show that rocks can be defined as “emitters”, with emissivity generally ranging from 0.89 to 0.99. Such variability arises from both their intrinsic properties, such as the presence of pores and the different thermal behavior of minerals, and the surface conditions, such as polishing treatments for ornamental stones. The resulting emissivity values are reported and commented on herein for each different studied lithology, thus providing not only a reference dataset for practical use, but also laying the foundation for further scientific studies, also aimed at widening the rock aspects to investigate through IRT.

Infrared thermography has been widely adopted in many applications for material structure inspection, where data analysis methods are often implemented to elaborate raw thermal data and to characterize material structural properties. Herein, a multiscale thermographic data analysis framework is proposed and applied to building structure inspection. In detail, thermograms are first collected by conducting solar loading thermography, which are then decomposed into several intrinsic mode functions under different spatial scales by multidimensional ensemble empirical mode decomposition. At each scale, principal component analysis (PCA) is implemented for feature extraction. By visualizing the loading vectors of PCA, the important building structures are highlighted. Compared with principal component thermography that applies PCA directly to raw thermal data, the proposed multiscale analysis method is able to zoom in on different types of structural features.

International audience; Fire‐induced decomposition of composite materials involves complex and coupled multi‐physics phenomena experienced for instance in standard tests (cone calorimeter, FAR 25.856(b):2003 and ISO 2685:1998(e)). It is proposed to address this issue in a simplified laboratory facility using a gas burner embedded with coupled measurement techniques to assess all desired physical quantities. A focus is given in this study on non‐intrusive (no coating required) digital image correlation (DIC) and infra‐red thermography (IRT) measurements. Out‐of‐plane displacement and temperature of the unexposed surface were accurately measured as a function of time to investigate the 3D fire behaviour of a composite laminate used in the aircraft industry. Those complementary measurements are carried out on a purpose‐made experimental set‐up in order to provide relevant and correlated information from FOLKI‐D algorithm and to identify the damage mechanisms.

This paper presents an advanced methodology for the detection of damage in aircraft composite materials based on the sensor fusion of two image-based non-destructive evaluation techniques. Both of the techniques, phased-array ultrasonics and infra-red thermography, are benchmarked on an aircraft-grade painted composite material skin panel with stringers. The sensors systems for carrying out the inspections have been developed and miniaturized for being integrated on a vortex-robotic platform inspector, in the framework of a larger research initiative, the Horizon-2020 ‘CompInnova’ project.

International audience; Shape memory alloys (SMAs) are promising mechanocaloric materials for the creation of innovative heating/cooling systems. The present paper proposes a simple concept of "porous" SMA material in the form of a two-dimensional (2D) "granular" system. The basic idea is to place SMA cylinders in parallel and in contact, thus creating a 2D granular material, with fluid circulation in the third dimension (i.e. in the longitudinal direction of the cylinders). The study is dedicated to the validation of the mechanocaloric character of such a material system subjected to confined compression. First, experiments were conducted using superelastic nickel-titanium rods of various diameters, enabling us to create different bidispersity levels for the granular medium. Infrared thermography was used to analyze the temperature changes within the cylinders. Second, air was used as the circulating fluid for the sake of concept validation. Comparison between different levels of bidispersity of the granular system showed that a nearly-monodisperse configuration could be advantageous to optimize the concept.