A majority of the primary roadways in the United States are constructed using hot-mix asphalt (HMA) placed over a granular base material. The strength of this pavement system is strongly influenced by the local environmental conditions. Excessive moisture in a granular base layer can cause that layer to lose its structural contribution by reducing the area over which loading may be distributed. Excessive moisture and fine particles can be transported by hydrostatic pressure to the surface layers, thus reducing the strength of the overlying HMA by contamination. Moisture in the surface HMA layers can cause deterioration through stripping and raveling. In addition, as HMA is a viscoelastic material, it behaves more as a viscous fluid at high temperatures and as an elastic solid at low temperatures. Between these two temperature extremes, a combination of these properties is evident. Thus, understanding the environmental effects on flexible pavements allows better prediction of pavement performance and behavior under different environmental conditions. As part of the ongoing pavement research at the Virginia Smart Road, instrumentation was embedded during construction to monitor pavement response to loading and environment; moisture content of the granular base layers and temperature of the HMA layers were among the responses monitored. The Virginia Smart Road, constructed in Blacksburg, Virginia, is a pavement test facility is approximately 2.5km in length, of which 1.3km is flexible pavement that is divided into 12 sections of approximately 100m each. Each flexible pavement section is comprised of a multi-layer pavement system and possesses a unique structural configuration. The moisture content of aggregate subbase layers was measured utilizing two types of Time-Domain Reflectometry (TDR) probes that differed in their mode of operation. The temperature profile of the pavement was measured using thermocouples. Data for the moisture content determination was collected and results from two probe types were evaluated. In addition, the differences in the moisture content within the aggregate subbase layer due to pavement structural configuration and presence of a moisture barrier were investigated. It was shown that the two TDR probe types gave similar results following a calibration procedure. In addition to effects due to pavement structure and subgrade type, the presence of a moisture barrier appeared to reduce the variability in the moisture content caused by precipitation. Temperature profile data was collected on a continuous basis for the purpose of developing a pavement temperature prediction model. A linear relationship was observed between the temperature given by a thermocouple near the ground surface and the pavement temperature at various depths. Following this, multiple-linear regression models were developed to predict the daily maximum or minimum pavement temperature in the HMA layers regardless of binder type or nominal maximum particle size. In addition, the measured ambient temperature and calculated received daily solar radiation were incorporated into an additional set of models to predict daily pavement temperatures at any location. The predicted temperatures from all developed models were found to be in agreement with in-situ measured temperatures. / Ph. D.

Polymer extrusion is an energy intensive process whereby the simultaneous action of viscous shear and thermal conduction are used to convert solid polymer to a melt which can be formed into a shape. To optimise efficiency, a homogeneous melt is required with minimum consumption of process energy. In this work, in-process monitoring techniques have been used to characterise the thermal dynamics of the single screw extrusion process with real-time quantification of energy consumption. Thermocouple grid sensors were used to measure radial melt temperatures across the melt flow at the entrance to the extruder die. Moreover, an infrared sensor flush mounted at the end of the extruder barrel was used to measure non-invasive melt temperature profiles across the width of the screw channel in the metering section of the extruder screw. Both techniques were found to provide useful information concerning the thermal dynamics of the extrusion process; in particular this application of infrared thermometry could prove useful for industrial extrusion process monitoring applications. Extruder screw geometry and extrusion variables should ideally be tailored to suit the properties of individual polymers but in practise this is rarely achieved due the lack of understanding. Here, LDPE, LLDPE, three grades of HDPE, PS, PP and PET were extruded using three geometries of extruder screws at several set temperatures and screw rotation speeds. Extrusion data showed that polymer rheology had a significant effect on the thermal efficiency on the extrusion process. In particular, melt viscosity was found to have a significant effect on specific energy consumption and thermal homogeneity of the melt. Extruder screw geometry, set extrusion temperature and screw rotation speed were also found to have a direct effect on energy consumption and melt consistency. Single flighted extruder screws exhibited poorer temperature homogeneity and larger fluctuations than a barrier flighted screw with a spiral mixer. These results highlighted the importance of careful selection of processing conditions and extruder screw geometry on melt homogeneity and process efficiency. Extruder scale was found to have a significant influence on thermal characteristics due to changes in surface area of the screw, barrel and heaters which consequently affect the effectiveness of the melting process and extrusion process energy demand. In this thesis, the thermal and energy characteristics of two single screw extruders were compared to examine the effect of extruder scale and processing conditions on measured melt temperature and energy consumption. Extrusion thermal dynamics were shown to be highly dependent upon extruder scale whilst specific energy consumption compared more favourably, enabling prediction of a process window from lab to industrial scale within which energy efficiency can be optimised. Overall, this detailed experimental study has helped to improve understanding of the single screw extrusion process, in terms of thermal stability and energy consumption. It is hoped that the findings will allow those working in this field to make more informed decisions regarding set conditions, screw geometry and extruder scale, in order to improve the efficiency of the extrusion process. / Engineering and Physical Sciences Research Council

No / Polymer extrusion is an energy intensive process, which is often run at less than optimal conditions. The extrusion process consists of gradual melting of solid polymer by thermal conduction and viscous shearing between a rotating screw and a barrel; as such it is highly dependent upon the frictional, thermal and rheological properties of the polymer. Extruder screw geometry and extrusion variables should ideally be tailored to suit the properties of individual polymers, but in practice this is rarely achieved due to the lack of understanding of the process. Here, in-process monitoring techniques have been used to characterise the thermal dynamics of the extrusion process. Novel thermocouple grid sensors have been used to measure melt temperature fields within flowing polymer melts at the entrance to an extruder die in conjunction with infra-red thermometers and real-time quantification of energy consumption. A commercial grade of polyethylene has been examined using three extruder screw geometries at different extrusion operating conditions to understand the process efficiency. Extruder screw geometry, screw rotation speed and set temperature were found to have a significant effect on the thermal homogeneity of the melt and process energy consumed. (C) 2012 Elsevier Ltd. All rights reserved.

No / The development and validation of a sensor for extrusion melt temperature field measurement is described. A grid of opposing thermocouple wires was constructed and held in position by a supporting frame. Wires were joined together at crossing points to form thermocouple junctions, which were computer monitored. The mesh was used to monitor melt temperature fields during single screw extrusion at the die entrance. Design and construction of the mesh is described in addition to experimental optimization of wire diameter and junction forming. Calibration of the sensor and potential measurement errors including shear heating effects are discussed. Initial results from single screw extrusion are presented for a commercial grade of low density polyethylene using five- and seven-junction thermocouple meshes. The dependence of melt temperature profile on screw speed is illustrated. At low screw speeds melt temperature profiles were flat in shape and higher than set wall temperatures. At higher screw speeds the profiles became more pointed in shape. Use of higher resolution sensors exposed more complex temperature profiles with shoulder regions.

No / Polymer extrusion is fundamental to the processing of polymeric materials and melt flow temperature homogeneity is a major factor which influences product quality. Undesirable thermal conditions can cause problems such as melt degradation, dimensional instability, weaknesses in mechanical/optical/geometrical properties, and so forth. It has been revealed that melt temperature varies with time and with radial position across the die. However, the majority of polymer processes use only single-point techniques whose thermal measurements are limited to the single point at which they are fixed. Therefore, it is impossible for such techniques to determine thermal homogeneity across the melt flow. In this work, an extensive investigation was carried out into melt flow thermal behavior of the output of a single extruder with different polymers and screw geometries over a wide range of processing conditions. Melt temperature profiles of the process output were observed using a thermocouple mesh placed in the flow and results confirmed that the melt flow thermal behavior is different at different radial positions. The uniformity of temperature across the melt flow deteriorated considerably with increase in screw rotational speed while it was also shown to be dependent on process settings, screw geometry, and material properties. Moreover, it appears that the effects of the material, machine, and process settings on the quantity and quality of the process output are heavily coupled with each other and this may cause the process to be difficult to predict and variable in nature. (C) 2013 Society of Plastics Engineers

Les caractérisations thermiques à l'échelle nanométrique restent un défi depuis l'émergence de dispositifs nano structurés. Ayant des avantages en termes de résolution latérale par rapport aux techniques de champ lointain, la microscopie thermique à balayage est devenue un outil essentiel pour la caractérisation locale des propriétés thermiques des matériaux. Dans le cadre du projet européen « Quantiheat », plusieurs laboratoires ont travaillé ensemble pour essayer de comprendre et d'obtenir des mesures quantitatives couvrant les échelles spatiales allant du micro au nanomètre.Ce document contient six chapitres avec quatre parties principales, dans lesquelles des sondes SThM à thermocouples microfilaires ont été utilisées pour améliorer nos connaissances en thermométrie quantitative à cette échelle. Ce type de sonde a été développé et amélioré pendant plusieurs années. Nous démontrons qu'il est adapté pour mesurer la température d’échantillons actifs ainsi que la conductivité thermique d’échantillons passifs.Grâce à la thèse, la dernière version du microscope (matériel, logiciel) et la conception de la sonde sont présentés. Fixé sur un diapason en quartz, la force de contact pointe-échantillon peut être quantifiée. Placé dans une chambre à vide, ce système permet un contrôle complet des paramètres prédominants sur la mesure, tels que la pression de l'air et la force de contact. Les mesures en modes actif et passif ont pu être menées grâce aux échantillons fournis par les partenaires du projet « Quantiheat » afin de démontrer que des mesures quantitatives sont envisageables. En changeant les conditions ambiantes allant du vide primaire à la pression ambiante, les mécanismes de transfert de chaleur de l'échantillon-pointe ont été analysés en détail pour mettre en évidence le rôle prépondérant de l'air et des conductions de contact solide-solide. / Thermal characterizations at nano-scale remain a challenge since the emergence of nano-structured devices. Having advantages in term of lateral resolution compared to far field techniques, the scanning thermal microscopy has become an essential tool for local materials heat transport characterization. In the frame of the European Quantiheat Project, several laboratories have worked together trying to figure out and to obtain quantitative thermal measurements covering spatial scales from the micrometre to the nanometre.This document contains six chapters with four main parts, in which micro-wire thermocouple based SThM probes have been used to enhance our knowledge in quantitative thermometry at this scale. This kind of probe has been developed and improved for several years. We demonstrate that it is adapted for measuring temperature of active samples as well as thermal conductivity of passive samples.Through the dissertation, the last version of the microscope (hardware, software) and probe design are presented. Attached on a quartz tuning fork, the tip-sample contact force can be quantified. Placed in a vacuum chamber, this system permits a full control of predominant parameters on the measurement such as air pressure and contact force. Thanks to samples provided by Quantiheat partners, measurements in active and passive modes have been performed to demonstrate that quantitative measurements are feasible. By changing ambient conditions from primary vacuum to ambient pressure, the tip-sample heat transfer mechanisms have been analysed in detail to reveal the preponderant role of air and solid-solid contact conductions.

[pt] A presente Dissertação de Mestrado, intitulada Avaliação metrológica da estabilidade termoelétrica do termopar tipo K, refere-se à verificação de desvios de estabilidade da força eletromotriz induzidos pelo uso de termopares tipo k com isolação mineral de 3mm de diâmetro. Foram analisadas oito amostras de quatro fabricantes nacionais de termopares, após sua exposição a um campo de temperatura de 995 diferente de 0,5 graus Celsius, portanto próximo ao seu limite de aplicabilidade (1070 graus Celsius), simulando uma condição de uso em regime contínuo. As amostras foram recozidas a uma temperatura de 1000 graus Celsius para regularizar o estado de tensão antes dos ensaios realizados e suas condições físico-químicas avaliadas antes dos experimentos, com base em analises química e metalográficas. As variações da força eletromotriz, induzidas pelo uso, foram avaliadas com base em calibrações que antecederam e sucederam a exposição das amostras ao campo de temperatura previamente determinado, realizadas contra temperaturas de referência obtidas pelo uso de seis células de pontos fixos (Ag, Al, Zn, Sn, In e Ga). Como contextualização, a dissertação também apresenta um breve histórico relacionado à medição da temperatura e ao uso de termopares tipo K, além de fundamentar a teoria que sustenta o desenvolvimento da pesquisa, suas conclusões, estabelecendo, assim, as bases para recomendações de novos trabalhos neste campo. Como resultado central da investigação conduzida, comprovou- se que, para as condições de trabalhos impostas (calibração em células de ponto fixo e exposição à temperatura de 995 graus Celsius em regime contínuo), todas as amostras apresentaram desvios nas suas curvas de calibração que variam na faixa de 0,2 a 4,0 graus Celsius, explicitando intervalos superiores às expectativas dos usuários. O período de vida dos experimentos completou-se com um intervalo de tempo de 134 h de submissão ao campo de temperatura. A pesquisa é de relevância no contexto industrial e científico pelo fato de o termopar tipo K representar cerca de 70 por cento do mercado brasileiro de termopares, e ser uma expectativa e recomendação do Instituto Nacional de Metrologia do Brasil, o Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (INMETRO). / [en] The present masters dissertation entitled Metrological Assessment of Thermoelectric Stability of Type K Thermocouple, refers to the verification of stability deviations in the electromotive force induced by the use of type K thermocouple with 3mm diameter mineral insulation. Eight samples from four national thermocouples manufacturers were analyzed, after their exposure to a 995 different to 0,5 temperature field, thus very close to its applicability threshold (1070 Celsius degree), simulating a continuous regime condition of use. The samples were annealed at 1000 Celsius degree to regulate the strain state before the tests; their physical-chemical conditions were assessed before the essays based on chemical and metallographic analyses. The variations in electromotive forces induced by use were assessed based on calibrations made before and after the exposure of the samples to the temperature field previously determined,performed against reference temperatures obtained with the use of six fixed- point cells (Ag, Al, Zn, Sn, In and Ga). The dissertation also presents a brief history on temperature gauging and the use of type K thermocouples, in addition to showing the basis of the theory that supports research development, its conclusions, thus establishing the basis for recommendations of new research in this field. The main result of the research carried out enabled us to prove that, for the imposed working conditions (calibration on fixed-point cells and exposure to temperatures of 995 Celsius degree under a continuous regime), all the samples presented deviations in their calibration curves which varied from 0.2 to 4.0 Celsius degree, which made explicit higher intervals than those expected by the users. The test s lifetime was completed with a 134 hour time interval submission to the temperature field. The research is relevant in the industrial and scientific context because type K thermocouples represent approximately 70percent of the Brazilian thermocouple market, and because it is an expectation and a recommendation of the National Metrology Institute of Brazil - the Instituto Nacional de Metrologia,Normalização e Qualidade Industrial (INMETRO).

En aéronautique, l’élaboration via des pré-imprégnés n’est pas toujours adaptées àla fabrication de nouvelles pièces de formes complexes ou de grandes dimensions. Desprocédés directs existent, dénommés Liquid Composites Molding (LCM), tels que leResin Transfer Moulding (RTM) ou les procédés d’infusion de résine, comme le LiquidResin Infusion (LRI) et le Resin Film Infusion (RFI). Actuellement, environ 5 à 10%des pièces composites sont fabriqués par ces procédés directs. Avec le procédé RTM,les tolérances dimensionnelles et la porosité peuvent être maîtrisées et on peut atteindredes pièces haute qualité, mais son industrialisation est complexe et les modèlesmécaniques doivent être améliorés pour réaliser des simulations représentatives. Parcontre, les procédés d’infusion peuvent être utilisés dans des conditions plus flexibles,par exemple, dans des moules ouverts à sac vide en nylon ou silicone, à faible coût. Parconséquent, les procédés de LRI et RFI sont particulièrement adaptés pour les petites etmoyennes entreprises car les investissements sont plus faibles par rapport à d’autresprocédés de fabrication.Les procédés par infusion de résine LRI ou RFI sont basés sur l’écoulement d’unerésine liquide (pour RFI, après le cycle de température, la résine solide obtenir son étatliquide) à travers l’épaisseur d’un renfort fibreux sec dénommé préforme.L’optimisation du procédé est difficile à réaliser car le volume de la préforme changefortement pendant le procédé car elle est soumise à une pression extérieure et qu’il n’ya pas de contre-moule. Pour optimiser les paramètres de fabrication des matériauxcomposites par infusion de résine, il est nécessaire de mettre en oeuvre un modèlenumérique. Récemment, une modélisation de l'écoulement d’un fluide isotherme dansun milieu poreux compressible a été développée par P. Celle [1]. Avec ce modèlenumérique, nous avons simulé des cas test en 2D pour des géométries industriellesclassiques. Pour valider ce modèle numérique, des essais d’infusion d’une plaque par leprocédé LRI dans des conditions industrielles ont été réalisés. D’une part, la simulationnumérique permet de calculer le temps de remplissage, l’épaisseur de la préforme et lamasse de la résine durant l’infusion. D’autre part, nous avons suivi de procédéexpérimentalement par des micro-thermocouples, la fibre optique et la projection defranges. Un des points clefs de l’approche expérimentale est que l’écoulement de larésine et le comportement de la préforme dépendent intrinsèquement de paramètres quiévoluent pendant l’infusion de la résine, tels que la variation de l’épaisseur, le temps deremplissage et le taux volumique de fibres, via la perméabilité. Enfin, une comparaisonentre les résultats expérimentaux et la simulation numérique permet de valider lemodèle numérique. Cette confrontation des résultats permettra de mettre en lumière lesdifficultés et les limites de ce modèle numérique, afin d’améliorer les futurs modèles.De plus, ces deux approches constituent un bon moyen d’étudier et d’approfondir nosconnaissances sur les procédés d’infusion de résine, tout en développant un outil desimulation indispensable à la conception de pièces composites avancées. / Weight saving is still a key issue for aerospace industry. For instance 50% in weightof the B787 and A350 aircraft structures is made of CFRP, so it is necessary to makelighter thick and complex parts. Direct processes called Liquid Composite Molding(LCM), such as Resin Transfer Moulding (RTM) or Resin Infusion Process (LRI, RFI).At the present time, around 5 to 10% of the parts are manufactured by direct processesand the current trend is clearly to go ahead. In RTM process, the dimensional tolerancesand porosity fraction can be kept under control and high quality parts produced, but itsindustrialisation is complex and refined models are still needed to perform simulations.On the contrary, the resin infusion process can be utilized in flexible conditions, such asin low cost open moulds with vacuum bags in nylon or silicone. This type of processonly requires low resin pressure and the tooling is less expensive than RTM rigidmoulds. Therefore LRI and RFI processes are particularity suitable for small andmedium size companies because the investments are rather low compared to othermanufacturing process.Liquid Resin Infusion (LRI) processes are promising manufacturing routes toproduce large, thick or complex structural parts. They are based on the resin flowinduced across its thickness by pressure applied onto a preform / resin stacking.However, both thickness and fibre volume fraction of the final piece are not wellcontrolled since they result from complex mechanisms which drive the transientmechanical equilibria leading to the final geometrical configuration. In order tooptimize both design and manufacturing parameters, but also to monitor the LRIprocess, an isothermal numerical model has been developed by P. Celle [1], whichdescribes the mechanical interaction between the deformations of the porous mediumand the resin flow during infusion. With this numerical model, we have investigated theLRI process with classical industrial piece shapes. To validate the numerical model andto improve the knowledge of the LRI process, the researcher work details a comparisonbetween numerical simulations and an experimental study of a plate infusion testcarried out by LRI process under industrial conditions. From the numerical prediction,the filling time, the resin mass and the thickness of the preform can be determined. Onanother hand, the resin flow and the preform response can be monitored bymicro-thermocouples, optical fibre sensor and fringe projection during the filling stage.One key issue of this research work is to highlight the major process parameterschanges during the resin infusion stage, such as the preform and resin temperature, thevariations of both thickness and fiber volume fraction of the preform. Moreover, thesetwo approaches are both good ways to explore and improve our knowledge on the resininfusion processes, and finally, to develop simulation tools for the design of advancedcomposite parts.

In this work is described design of measuring and evaluation system for temperature rise tests in cooperation with ABB company. As temperature sensors are used thermocouples type L and measuring hardware consists of chassis cRIO 9073 and measuring card NI 9213. In LabVIEW 2011 is created software for cRIO and as well for control PC and structure of both programs is described in detail. Thesis includes also practical estimation of metrological parameters of created system.

Shape Memory Alloy is an amazing material, which can “remember” and return to its original shape when heated due to its temperature dependent phase transformation. Shape Memory Alloy wire has significant potential for application in the automobile industry due to its high ratio of energy / weight and silent actuation. However, a dependable method to measure the operating temperature of SMA wire and a reliable heat transfer model to characterize the dynamics of the SMA wire limit its widespread use in the automobile industry. This thesis presents a detailed description of the work performed to develop a reliable method for determining surface temperature of current carrying SMA wires and the development of a heat transfer correlation for natural convection cooling of heated SMA wires. The major findings of the research are as follows: When a spot welded thermocouple measures the temperature of a current carrying SMA wire, there is a “spurious voltage” ΔV added to the thermo electro-motive force (EMF) of the thermocouple as a result of a voltage drop across the two points of contact that the thermocouple wires make with the SMA wire. This leads to an erroneous temperature reading that can be higher or lower than the actual temperature depending on the direction of current flow. When the carrying current is reversed in direction, the “spurious voltage” becomes –ΔV allowing a correct temperature reading to be obtained by averaging the readings based on opposed current flow. A two-step spot welding procedure for attaching thermocouples to SMA wire can eliminate the influence of the “spurious voltage” in the temperature reading. By spot welding the thermocouple wires onto the SMA wire one by one, the thermocouple lead offset is eliminated and the thermocouple provides an accurate point source reading. Infrared thermal imaging can be a good supplement in the experiment to monitor errors in temperature readings from thermocouples. Due to the curvature of the SMA wire, the temperatures of the locations on the SMA wire that are the closest to the infrared camera represent the temperature of the SMA wire. So a line analysis across the SMA wire on the software “ThermaCAM” is required to determine the temperature of the SMA wire by infrared thermal imaging and the highest temperature on the line is the temperature of the SMA wire. A new natural convective heat transfer correlation comprising the inclination angle φ is developed based on experimental results, which can be used to predict the temperature of a SMA wire given its diameter and inclination angle. The comparisons show that the new correlation agrees with existing correlations in a vertical orientation and for small Rayleigh numbers (0.001 < RaD < 0.05) in the horizontal orientation. The correlation developed in this work for horizontal orientation tends to overestimate values of Nusselt numbers as predicted in other correlations when the Rayleigh number is high (0.05 < RaD < 0.6). It is speculated that this overestimation can be attributed to a temperature distortion associated with thermocouple measurement at or near ambient pressure conditions.