Dissertations / Theses: 'Thermal and mechanical models'

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Nguyen, Van-Tri. "Thermal and thermo-mechanical behavior of energy piles." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1160/document.

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Le comportement thermique et thermo-mécanique des pieux énergétiques est étudié par plusieurs approches : mesures au laboratoire sur des éprouvettes de sol, modélisation physique en modèle réduit, expérimentations sur pieu en vraie grandeur, et calculs numériques/analytiques. D’abord, la conductivité thermique d’un loess à l’état non saturé est mesurée en fonction de la teneur en eau et de la succion. Les résultats montrent une relation univoque entre la conductivité thermique et la teneur en eau pendant un cycle d’humidification/séchage alors qu’une boucle d’hystérésis est observée pour la relation entre la conductivité thermique et la succion. Deuxièmement, des essais thermiques sont réalisés sur un pieu énergétique expérimental en vraie grandeur pour étudier le transfert thermique à l’échelle réelle. Troisièmement, une solution analytique est proposée pour simuler la conduction thermique d’un pieu énergétique vers le sol environnant pendant un chauffage. Les tâches mentionnées ci-dessus concernant le comportant thermique sont ensuite complétées par des études sur le comportement thermo-mécanique des pieux énergétiques. D’un côté, des expérimentations sont réalisées sur un modèle réduit de pieu installé dans un sable sec ou dans une argile saturée. Trente cycles thermiques, représentant trente cycles annuels, sont appliqués au pieu sous différentes charges axiales en tête. Les résultats montrent un tassement irréversible avec les cycles thermiques ; ce tassement est plus important sous une charge axiale plus grande. De plus, le tassement est plus marqué pendant les premiers cycles thermiques et devient négligeable pour les cycles suivants. De l’autre côté, les travaux expérimentaux sur le modèle réduit de pieu sont complétés par les calculs numériques utilisant la méthode des éléments finis. Cette approche est d’abord validée avec les résultats obtenus sur le pieu modèle avant d’être utilisée pour prédire les résultats des expérimentations en vraie grandeur
The thermal and thermo-mechanical behavior of energy piles is investigated by various approaches: laboratory measurement on small soil samples, physical modeling on small-scale pile, experiments on real-scale pile, and analytical/numerical calculations. First, the thermal conductivity of unsaturated loess is measured simultaneously with moisture content and suction. The results show a unique relationship between thermal conductivity and moisture content during a wetting/drying cycle while a clear hysteresis loop can be observed on the relationship between thermal conductivity and suction. Second, thermal tests are performed on a full-scale experimental energy pile to observe heat transfer at the real scale. Third, an analytical solution is proposed to simulate conductive heat transfer from an energy pile to the surrounding soil during heating. The above-mentioned tasks related to the thermal behavior are then completed by studies on the thermo-mechanical behavior of energy piles. On one hand, experiments are performed on a small-scale pile installed either in dry sand or in saturated clay. Thirty thermal cycles, representing thirty annual cycles, are applied to the pile under various constant pile head loads. The results show irreversible pile head settlement with thermal cycles; the settlement is higher at higher pile head load. In addition, the irreversible thermal settlement is the most significant during the first cycles; it becomes negligible at high number of cycles. On the other hand, the experimental work with small-scale pile is completed with numerical calculations by using the finite element method. This approach is first validated with the results on small-scale pile prior to be used to predict the results of full-scale experiments

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Vilaithong, Rummiya [Verfasser]. "Models for Thermal and Mechanical Monitoring of Power Transformers / Rummiya Vilaithong." Aachen : Shaker, 2011. http://d-nb.info/1070150282/34.

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Kiley, Erin Marie. "Reduced-Dimensional Coupled Electromagnetic, Thermal, and Mechanical Models of Microwave Sintering." Digital WPI, 2016. https://digitalcommons.wpi.edu/etd-dissertations/212.

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In recent years, sintering of powdered materials in microwaves has emerged as a manufacturing technique with many potential advantages over conventional sintering methods, including the possibility of faster processing and finer microstructure, along with the potential for vast energy savings. However, the technique remains on the level of laboratory studies and is underutilized in industry, mostly due to the difficulty of controlling the process: the intrinsically nonuniform temperature pattern that results from microwave heating routinely induces nonuniform mechanical deformation. Mathematical models and computer simulations can help to clarify the factors that influence this process and aid experimentalists in the design of efficient processing equipment. Although a number of modelling techniques have been reported to this end, they appear to inadequately represent the entire chain of related physical phenomena, which involves interaction of the electromagnetic field with the material, heat transfer, and mechanical deformation, each of which is coupled with both of the others, and all of which occur on different time scales. In this work, we present an original comprehensive mathematical formulation that accounts for the chain of physical processes comprising microwave sintering in one- and two-dimensional scenarios. We develop models for simulating the coupled electromagnetic, thermal, and mechanical phenomena at their appropriate time and spatial scales, and in addition, we account for the temperature and density dependence of the full set of thermal and dielectric properties of the material undergoing sintering. The electromagnetic and temperature fields are approximated using finite difference methods, and the mechanical problem is solved using the Master Sintering Curve representation of the density kinetics, which gives a way of accounting for the effect of microscale transport on the macroscopic property of relative density. For constant-rate sintering trials, we use the exponential integral to compute the work of sintering, which reduces computation time. The presented algorithms are all implemented and shown in MATLAB and Python. Simulation of density and temperature evolution of the sintered sample shows processing times and shrinkage rates comparable to experimental results. This work lays a theoretical and computational foundation for modelling the general three-dimensional problem and computer-aided design of efficient sintering processes.

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Ogata, Sho. "Development of Coupled Thermal-Hydraulic-Mechanical-Chemical Models for Predicting Rock Permeability Change." Doctoral thesis, Kyoto University, 2019. http://hdl.handle.net/2433/244532.

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京都大学
0048
新制・課程博士
博士(工学)
甲第22051号
工博第4632号
新制||工||1722(附属図書館)
京都大学大学院工学研究科都市社会工学専攻
(主査)教授岸田潔, 教授木村亮, 教授小池克明
学位規則第4条第1項該当
Doctor of Philosophy (Engineering)
Kyoto University
DFAM

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Evans, Thomas C. (Thomas Carl) 1971. "Statistical usage models in mobile processor thermal design and testing." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/89389.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Sloan School of Management; in conjunction with the Leaders for Manufacturing Program at MIT, 2003.
Includes bibliographical references (p. 77).
by Thomas C. Evans.
S.M.

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Kokorev, A. E., A. O. Kiriak, and О. Г. Аврунін. "Some Models of Mechanical and Thermal Properties of Skin in the Context of Plastic Surgery." Thesis, Kharkiv, KNURE, 2019. http://openarchive.nure.ua/handle/document/10196.

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Urquiza, Fernandez Guillermo 1978. "Thermal model of an annular fuel cell." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/89920.

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Thesis (S.M. and S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.
Includes bibliographical references (p. 81).
by Guillermo Urquiza Fernandez.
S.M.and S.B.

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Lahoori, Mojdeh. "Thermo-hydro-mechanical behavior of an embankment to store thermal energy." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0252.

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Le stockage de chaleur dans des géostructures énergétiques telles que des remblais est réalisable en installant des échangeurs horizontaux au sein des différentes couches de sol compacté. Dans ce système, l'énergie thermique qui est injectée en été via un fluide caloporteur circulant dans les échangeurs de chaleur, peut être extraite en période hivernale. Dans ces conditions, lors de la mise en service, le sol compacté est soumis à des variations de température quotidiennes et saisonnières. Ces variations pourraient modifier les performances thermo-hydro-mécaniques du sol compacté. Ainsi, le but de cette étude est d'étudier les performances thermiques et mécaniques d'un sol compacté lorsqu'il est soumis à des variations de température monotones et cycliques. Le sol étudié est un limon fréquemment utilisé dans les constructions de remblais en France. Le comportement thermique et mécanique du sol est étudié à un état de compactage correspondant aux propriétés thermiques optimales. Dans cet état, le sol compacté est non saturé ce qui complexifie l'estimation de ses propriétés thermiques. Pour pallier à ces difficultés, dans cette étude, un modèle inverse est proposé pour estimer les propriétés thermiques du sol compacté. L’efficacité du modèle est testée sur un jeu de données acquises dans la gamme de 20 à 50 °C dans un modèle réduit en laboratoire. Les valeurs obtenues sont ensuite comparées à des mesures classiques en laboratoire (méthodes en régime transitoire et en régime permanent). Cette méthode pourrait permettre de suivre l’évolution des propriétés thermiques du stockage et ainsi assurer son efficacité tout au long de sa durée de vie. La question de la stabilité à long terme de ces structures soumises à des variations thermiques monotones (5, 20 et 50 °C) et cycliques (5 à 50 °C) est ensuite abordée à l'aide d'essais oedomètriques et d’essais de cisaillement direct à température contrôlée. Les résultats des essais de compressibilité ont montré que l'effet de la variation de température est plus prononcé sous une contrainte verticale supérieure à la pression de préconsolidation. Les indices de compression et de gonflement peuvent être considérés comme indépendants des variations de température. Donc le tassement global du remblai dû aux variations thermiques pourrait être considéré comme négligeable. Les résultats des essais de cisaillement direct ont montré que les variations de température (monotones ou cycliques) augmentent la cohésion ce qui est avantageux pour la capacité portante et la stabilité des pentes des remblais. Dans la phase de conception d'un remblai de stockage, ces résultats seraient utiles au dimensionnement du système si des trajectoires thermomécaniques similaires à celles de cette étude sont respectées. Dans une dernière partie, une simulation numérique prenant en compte l'interaction sol-atmosphère est réalisée afin d’évaluer la performance thermique de ce sol compacté en conditions naturelles. Différentes profondeurs d'installation de boucles d'échangeurs de chaleur sont testéss ainsi que différents scénarios de stockage. Les résultats ont montré que le sol compacté augmente de 8.5% les performances du système par rapport à l'installation d'une boucle horizontale dans le sol naturel (non compacté). Les résultats de deux scénarios différents ont montré qu’en été avec un fluide ayant une température d'entrée de 50 °C augmente significativement la performance du système. De plus, une installation plus profonde des boucles horizontales améliore également la performance du système. Il convient de noter que le remblai est en interaction avec l'atmosphère depuis ses surfaces supérieure et latérale, l'efficacité thermique de la structure pourrait être affectée en raison des pertes de chaleur. Par conséquent, il est préférable de placer les échangeurs de chaleur loin des surfaces supérieures et latérales
Nowadays, thermal energy storage in geostructures like embankments can be possible by installing the horizontal heat exchangers in different layers of compacted soil. In this system, the thermal energy is stored in summer via a fluid, circulating in the heat exchangers, to be extracted in the demand period. When the serviceability of embankment as a medium to store the thermal energy starts, the compacted soil will be subjected to the daily and seasonally temperature variations. These seasonal temperature variations could modify the thermo-hydro-mechanical performance of the compacted soil. Thus, the aim of this study is to investigate the thermal and mechanical performances of a compacted soil when it is subjected to monotonic and cyclic temperature variations. The studied soil is a sandy lean clay that is frequently used in embankment constructions in France. The thermal and mechanical behavior of the soil are investigated at a compaction state corresponding to the optimal thermal properties. However, this compacted soil is unsaturated and the estimation of its thermal properties is complex. In this study, an inverse analytical model is proposed to estimate the thermal properties of the soil using temperature monitoring in the range of 20 to 50 °C in a soil compacted in a large container. The estimated thermal parameters were compared to classical laboratory measurements (transient and steady-state methods). The comparison showed that the estimated values were close to the results obtained in transient laboratory method. Using this method, the thermal efficiency of the compacted soil can be verified in the lifetime of the storage system. To ensure the structure stability, long-term mechanical response of these systems subjected to monotonic and cyclic temperature variations should be investigated. To achieve this aim, using temperature-controlled oedometric and direct shear devices, consolidation and shear parameters of the studied soil at different monotonic (5, 20, and 50 °C) and cyclic (5 to 50 °C) temperatures were investigated. The results of temperature-controlled oedometric tests showed that the effect of the temperature variation is more pronounced under vertical pressures higher than the preconsolidation pressure. The compression and swelling indexes could be considered independent of temperature variations. Therefore, the overall settlement of the embankment due to thermal variation near the heat exchangers could be considered negligible. The results of temperature-controlled direct shear tests showed that the temperature variations (monotonic heating or cooling, or temperature cycles) increased the cohesion which is beneficial for the bearing capacity and slope stability of embankments. These results can be directly used in the design of embankments to store thermal energy exposed to similar thermo-mechanical paths. Finally, the thermal performance of the compacted soil is verified using a numerical simulation considering the soil atmosphere interaction. Different depths installation of heat exchanger loops and different heat storage scenarios were simulated. The results showed that the compacted soil increases 8.5% the systems performance compared to the horizontal loop installation in the local soil. The results of two different scenarios show that an inlet fluid temperature of 50 °C in summer increases highly the system performance (13.7% to 41.4%) while the improvement is less significant (0% to 4.8%) for the ambient inlet temperature. Moreover, a deeper installation of horizontal loops increases the system performance. From the numerical simulation results can be concealed that the embankment is in interaction with the atmosphere from its upper and lateral surfaces, the thermal efficiency of the structure could be affected due to heat losses. Therefore, it is preferable to place the heat exchangers away from the top and side surfaces

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Poller, Tilo. "Thermal and thermal-mechanical simulation for the prediction of fatigue processes in packages for power semiconductor devices." Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-154320.

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The knowledge about the reliability of power electronics is necessary for the design of converters. Especially for offshore applications it is essential to know, which fatigue processes happen and how the lifetime can be estimated. Numerical simulation is an important tool for the development of power electronic systems. This thesis analyse the thermal and thermal-mechanical behaviour of packages for power semiconductor devices with the help of simulations. One topic is the evaluation of different thermal models. The main focus is on the description of the thermal cross-coupling between the devices and the influence to the lifetime estimation. The power module is a well established package for power semiconductor devices. It will be explained how the heating period of power cycles influences the failure mode of this package type. Additionally, it will evaluated how SiC devices and DAB substrates influence the power cycling capability. The press-pack is in focus for high power applications as the package short-circuits during an electrical failure without external auxiliary systems. However, the knowledge about the power cycling behaviour is currently limited. With the help of simulations this behaviour will be analysed and possible weak points will be also derived. In the end of the work it will be discussed, how the lifetime can be estimated with help of FEM simulations
Für die Entwicklung von Umrichtern ist die Kenntnis über die Zuverlässigkeit der Leistungselektronik ein wichtiges Kernthema. Insbesondere für Offshore-Anwendungen ist das Wissen über die stattfindenden Ermüdungsprozesse und die Abschätzung der zu erwartenden Lebensdauer der Bauteile essentiell. Hierfür hat sich die Simulation als ein wichtiges Werkzeug für die Entwicklung und Lebensdauerbewertung von leistungselektronischen Anlagen etabliert. In der folgenden Arbeit wird das thermische und das thermisch-mechanische Verhalten der Leistungselektronik mittels Simulationen untersucht. Hierzu wird ein Vergleich zwischen verschiedenen thermischen Modellen für Leistungsbauelemente durchgeführt. Schwerpunkt ist die Beschreibung der thermischen Kopplung zwischen den Chips und deren Einfluss auf die Lebensdauerabschätzung. Ein weiterer Schwerpunkt ist das Leistungsmodul, welches sich als ein Standardgehäuse etabliert hat. Dazu wird erklärt, wie die Variation der Einschaltzeit im aktiven Lastwechseltest den Fehlermodus dieses Gehäusetyps beeinflusst. Weiterhin wird untersucht, wie SiC als Leistungshalbleiter und DAB als Substrat die Zuverlässigkeit beein- flusst. Der Press-Pack ist für Hochleistungsapplikationen von hohem Interesse, da dieses Gehäuse im elektrischen Fehlerfall ohne äußere Unterstützung kurzschliesst. Jedoch ist das Wissen über diese Gehäusetechnologie unter aktiven Lastwechselbedingungen sehr limitiert. Mit Hilfe von Simulationen wird dieses Verhalten untersucht und mögliche Schwachpunkte abgeleitet. Am Ende der Arbeit werden Möglichkeiten untersucht, wie Mithilfe von FEM Simulationen die Lebensdauer von Leistungsmodulen evaluiert werden kann

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Poller, Tilo. "Thermal and thermal-mechanical simulation for the prediction of fatigue processes in packages for power semiconductor devices." Doctoral thesis, Universitätsverlag der Technischen Universität Chemnitz, 2014. https://monarch.qucosa.de/id/qucosa%3A20135.

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The knowledge about the reliability of power electronics is necessary for the design of converters. Especially for offshore applications it is essential to know, which fatigue processes happen and how the lifetime can be estimated. Numerical simulation is an important tool for the development of power electronic systems. This thesis analyse the thermal and thermal-mechanical behaviour of packages for power semiconductor devices with the help of simulations. One topic is the evaluation of different thermal models. The main focus is on the description of the thermal cross-coupling between the devices and the influence to the lifetime estimation. The power module is a well established package for power semiconductor devices. It will be explained how the heating period of power cycles influences the failure mode of this package type. Additionally, it will evaluated how SiC devices and DAB substrates influence the power cycling capability. The press-pack is in focus for high power applications as the package short-circuits during an electrical failure without external auxiliary systems. However, the knowledge about the power cycling behaviour is currently limited. With the help of simulations this behaviour will be analysed and possible weak points will be also derived. In the end of the work it will be discussed, how the lifetime can be estimated with help of FEM simulations.
Für die Entwicklung von Umrichtern ist die Kenntnis über die Zuverlässigkeit der Leistungselektronik ein wichtiges Kernthema. Insbesondere für Offshore-Anwendungen ist das Wissen über die stattfindenden Ermüdungsprozesse und die Abschätzung der zu erwartenden Lebensdauer der Bauteile essentiell. Hierfür hat sich die Simulation als ein wichtiges Werkzeug für die Entwicklung und Lebensdauerbewertung von leistungselektronischen Anlagen etabliert. In der folgenden Arbeit wird das thermische und das thermisch-mechanische Verhalten der Leistungselektronik mittels Simulationen untersucht. Hierzu wird ein Vergleich zwischen verschiedenen thermischen Modellen für Leistungsbauelemente durchgeführt. Schwerpunkt ist die Beschreibung der thermischen Kopplung zwischen den Chips und deren Einfluss auf die Lebensdauerabschätzung. Ein weiterer Schwerpunkt ist das Leistungsmodul, welches sich als ein Standardgehäuse etabliert hat. Dazu wird erklärt, wie die Variation der Einschaltzeit im aktiven Lastwechseltest den Fehlermodus dieses Gehäusetyps beeinflusst. Weiterhin wird untersucht, wie SiC als Leistungshalbleiter und DAB als Substrat die Zuverlässigkeit beein- flusst. Der Press-Pack ist für Hochleistungsapplikationen von hohem Interesse, da dieses Gehäuse im elektrischen Fehlerfall ohne äußere Unterstützung kurzschliesst. Jedoch ist das Wissen über diese Gehäusetechnologie unter aktiven Lastwechselbedingungen sehr limitiert. Mit Hilfe von Simulationen wird dieses Verhalten untersucht und mögliche Schwachpunkte abgeleitet. Am Ende der Arbeit werden Möglichkeiten untersucht, wie Mithilfe von FEM Simulationen die Lebensdauer von Leistungsmodulen evaluiert werden kann.

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Liu, Jianxin. "A porosity-based model for coupled thermal-hydraulic-mechanical processes." University of Western Australia. Centre for Petroleum, Fuels and Energy, 2010. http://theses.library.uwa.edu.au/adt-WU2010.0113.

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[Truncated abstract] Rocks, as the host to natural chains of coupled thermal, hydraulic and mechanical processes, are heterogeneous at a variety of length scales, and in their mechanical properties, as well as in the hydraulic and thermal transport properties. Rock heterogeneity affects the ultimate hydro-carbon recovery or geothermal energy production. This heterogeneity has been considered one important and difficult problem that needs to be taken into account for its effect on the coupled processes. The aim of this thesis is to investigate the effect of rock heterogeneity on multi-physical processes. A fully coupled finite element model, hereinafter referred to as a porosity-based model (PBM) was developed to characterise the thermal-hydraulic-mechanical (THM) coupling processes. The development of the PBM consists of a two-staged workflow. First, based on poromechanics, porosity, one of the inherent rock properties, was derived as a variant function of the thermal, hydraulic and mechanical effects. Then, empirical relations or experimental results, correlating porosity with the mechanical, hydraulic and thermal properties, were incorporated as the coupling effects. In the PBM, the bulk volume of the model is assumed to be changeable. The rate of the volumetric strain was derived as the difference of two parts: the first part is the change in volume per unit of volume and per unit of time (this part was traditionally considered the rate of volumetric strain); and the second is the product of the first part and the volumetric strain. The second part makes the PBM a significant advancement of the models reported in the literature. ... impact of the rock heterogeneity on the hydro-mechanical responses because of the requirement of large memory and long central processing unit (CPU) time for the 3D applications. In the 2D PBM applications, as the thermal boundary condition applied to the rock samples containing some fractures, the pore pressure is generated by the thermal gradient. Some pore pressure islands can be generated as the statistical model and the digital image model are applied to characterise the initial porosity distribution. However, by using the homogeneous model, this phenomenon cannot be produced. In the 3D PBM applications, the existing fractures become the preferential paths for the fluid flowing inside the numerical model. The numerical results show that the PBM is sufficiently reliable to account for the rock mineral distribution in the hydro-mechanical coupling processes. The applications of the statistical method and the digital image processing technique make it possible to visualise the rock heterogeneity effect on the pore pressure distribution and the heat dissipation inside the rock model. Monitoring the fluid flux demonstrates the impact of the rock heterogeneity on the fluid product, which concerns petroleum engineering. The overall fluid flux (OFF) is mostly overestimated when the rock and fluid properties are assumed to be homogeneous. The 3D PBM application is an example. As the rock is heterogeneous, the OFF by the digital core is almost the same as that by the homogeneous model (this is due to that some fractures running through the digital core become the preferential path for the fluid flow), and around 1.5 times of that by the statistical model.

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Uchaipichat, Anuchit Civil &amp Environmental Engineering Faculty of Engineering UNSW. "Experimental investigation and constitutive modelling of thermo-hydro-mechanical coupling in unsaturated soils." Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/22068.

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A thermo-elastic-plastic model for unsaturated soils has been presented based on the effective stress principle considering the thermo-mechanical and suction coupling effects. The thermo-elastic-plastic constitutive equations for stress-strain relations of the solid skeleton and changes in fluid content and entropy for unsaturated soils have been established. A plasticity model is derived from energy considerations. The model derived covers both associative and non-associative flow behaviours and the modified Cam-Clay is considered as a special case. All model coefficients are identified in terms of measurable parameters. To verify the proposed model, an experimental program has been developed. A series of controlled laboratory tests were carried out on a compacted silt sample using a triaxial equipment modified for testing unsaturated soils at elevated temperatures. Imageprocessing technique was used for measuring the volume change of the samples subjected to mechanical, thermal and hydric loading. It is shown that the effective critical state parameters M, ???? and ???? are independent of temperature and matric suction. Nevertheless, the shape of loading collapse (LC) curve was affected by temperature and suction. Furthermore, the temperature change affected the soil water characteristic curve and an increase in temperature caused a decrease in the air entry suction. The simulations from the proposed model are compared with the experimental results. The model calibration was performed to extract the model parameters from the experimental results. Good agreement between the results predicted using the proposed model and the experimental results was obtained in all cases.

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Li, Zhonglin. "Tribological, Kinetic and Thermal Characteristics of Copper Chemical Mechanical Planarization." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1378%5F1%5Fm.pdf&type=application/pdf.

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Ho, Hsin-Ni. "Development and evaluation of a thermal model for haptic interfaces." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38696.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.
Includes bibliographical references (leaves 147-152).
The thermal interaction between the skin and an object is influenced by the thermal properties and initial temperatures of the skin and object, and by the contact force and surface roughness of the contact surfaces. This thermal interaction is modeled in this research which characterizes the transient thermal responses during contact. The thermal model was evaluated in psychophysical and physiological experiments by determining whether simulated thermal feedback generated based on the model was capable of conveying information to users that was similar to that provided by real materials, and by comparing the temperature responses of the skin predicted by the model and elicited by real materials. In order to obtain precise skin temperature measurements, an infrared thermal measurement system was designed to overcome the limitations imposed by thermal sensors and to determine the influence of contact pressure on the skin temperature responses during contact. The results from the psychophysical and physiological experiments validated the thermal model proposed in this research within the typical contact force range of manual exploration. A thermal display based on this model is able to convey thermal cues that can be used to perceive and identify objects as effectively as those provided by real materials.
by Hsin-Ni Ho.
Ph.D.

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Martin, Gregory T. (Gregory Thomas) 1966. "A thermal model for rapid hyperthermia therapy planning and evaluation." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11493.

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Radhakrishnan, Sadhana. "Stress Analysis of Embedded Devices Under Thermal Cycling." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4075.

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Embedded active and passive devices has been increasingly used by in order to integrate more functions inside the same or smaller size device and to meet the need for better electrical performance of the component assemblies. Solder joints have been used in the electronic industry as both structural and electrical interconnections between electronic packages and printed circuit boards (PCB). When solder joints are under thermal cyclic loading, mismatch in coefficients of thermal expansion (CTE) between the printed circuit boards and the solder balls creates thermal strains and stresses on the joints, which may finally result in cracking. Consequently, the mechanical interconnection is lost, leading to electrical failures which in turn causes malfunction of the circuit or whole system. When a die is embedded into a substrate, Young's modulus of the die is larger than one of the core of the substrate and the CTEs of the die is smaller than those of the substrate. As a result, mismatch in coefficients of thermal expansions (CTE) between the substrate with the embedded device and the solder balls may increase. In the present study, finite element method (FEM) is employed to find out the stress and strain distribution of ball grid array(BGA) solders under thermal cycling. The ANAND model for viscoplasticity is employed for this purpose.

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Hossain, Mohammad Akram. "Thermal Characteristics of Microinverters on Dual-axis Trackers." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1396888841.

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Häggström, Martin. "Thermal modelling of a truck gearbox." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-63753.

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The thermal regime of a gearbox is of considerable importance to its performance. Several significant gearbox parameters, such as the efficiency and fatigue life of its components, are temperature dependent. It is thus important to be able to determine the temperatures of the gearbox components during operation, but they are difficult to measure experimentally. A simulation model capable of predicting these temperatures would therefore be a valuable tool. The objective of this master’s thesis was to create a model capable of simulating the thermal regime of a truck gearbox during operation. To do this, mechanical losses in the gearbox, heat exchange with the surroundings, as well as heat transfer between components had to be accounted for. The model was created using the 1D simulation software LMS Imagine.Lab Amesim 14.0, and is based on a combination of mechanical and thermal networks. Details of the mechanical and thermal interactions between components are calculated using empirical and analytical formulas for mechanical losses and heat transfer. The result of the thesis is a model which can be used to simulate either real or idealised load cases, from which temperatures of gear wheels, shafts, bearings, housing and gearbox oil may be studied, as well as gearbox losses and heat transfer. Comparisons between simulated and measured gearbox efficiencies show good correlation. It is also shown that the model can predict oil temperatures which agree with in-vehicle measurements. Due to a lack of measurement data, most simulated component temperatures cannot be compared to measured values. However, temperature measurements performed for one of the gear wheels indicate that the model can be used to predict their temperature. In order to demonstrate the capabilities of the model, example results from both real and idealised load cases are presented.

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Stell, Brandon. "Thermal-Fluid Dynamic Model of Luge Steels." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1793.

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Luge is an Olympic sport in which athletes ride feet-first on sleds down an ice-covered track. Competitors spring from the starting position and accelerate their sled by paddling with spiked gloves against the ice surface. Once the Luger leaves the starting section, their downhill motion is solely propelled by the effects of gravity. Athletes compete, one after the other, for the fastest time. Runs can differ by as little as a thousandth of a second, meaning that every minor sled adjustment, change of line choice, and shift of body position is critical. In the past, the sport of Luge has progressed through a series of steps involving trial and error, where changes to the sled and strategy rely more on intuition and race results, rather than in-depth, mathematical analysis. In an effort to try and improve track times for the US Olympic Luge team, a track and driver model is in development in order to simulate a sled going down the track. By doing this, the hope is to be able to pinpoint areas of possible improvement to the sled and see how adjustments can affect the optimum line down the track. A part of this model, which is the focus of the following paper, is the inclusion of an analysis to identify the frictional relationship between the ice surface and the steels of the sled. The model created of the ice-steel interaction was put in the form of a function file, which includes inputs of down force, ice temperature, sled velocity, and steel geometry. Creation of this model and completion of a set of parametric studies allowed for further understanding the interaction between the sled steels and ice surface, specifically applying to the sport of Luge. The model predicts for lower temperatures that at slower sled velocities the coefficient of friction is greater compared to faster sled velocities. This relationship inverts as the ice temperature moves closer to the melting temperature. A sharper steel edge radius was found to be beneficial in lowering the coefficient of friction at lower sled velocities. The sharp edge radius friction benefit decreases as the sled speed increases and is predicted to actually increase friction slightly compared to duller blades at greater velocities. A flat as possible rocker radius lowers friction at all sled velocities, as well as in banked turns where two contact patches are possible. On curves, the pressure on the steel is increased due to the effects of centripetal accelerations. A 1 g versus 5 g normal loading, experienced on the last turns of the track, increases the coefficient of friction on the blade, but also increases the allowable lateral force on the sled before side slip occurs. Understanding the relationships of these parameters, along with the information that may be gained from the driver model, may prove to be useful in choosing optimum sled characteristics and line choice.

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Verma, Navni. "Development and Demonstration of Thermal Contact Conductance (TCC) Models for Contact Between Metallic Surfaces." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555452213472626.

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Zhou, Yafei. "Thermo-hydro-mechanical models for saturated and unsaturated porous media." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ36805.pdf.

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AL-AZMI, BADER SHABEEB. "ANALYSIS OF TRANSPORT MODELS AND COMPUTATION ALGORITHMS FOR FLOW THROUGH POROUS MEDIA." The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1051059625.

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23

Alrobaian, Abdulrahman Abdullah. "Multi-Spectral Remote Thermal Imaging for Surface Emissivity and Estimation of Roof R-Values Using Physics-Based and Data Mining Models." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton148898993590168.

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24

Tian, Ning. "A general thermal thickness model and a heating rate related ignition criterion for combustible solids." Thesis, The University of North Carolina at Charlotte, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3608480.

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The objective of this research is to investigate the ignition behavior of combustible solid materials in fire. Three key tasks were conducted for it: (1) a new theoretical temperature profile prediction model, referred as General Thermal Thickness (GTT) model, was proposed and then validated by the experimental data from E-glass/polyester composite panels at different heat fluxes; (2) a new ignition criterion (the Heating Rate-related Ignition Temperature (HRIT) criterion) was proposed and its accuracy under various heat fluxes was shown by comparing with experimental data of different materials; (3) uncertainty and sensitivity analyses were conducted on a new integrated ignition prediction model (i.e. the GTT combined with the HRIT ignition criterion), to investigate the variations in ignition and identify key affecting factors.

A simplified heat transfer model was constructed and solved in order to theoretically predict the temperature profile of the GTT combustible solid materials subjected to one-sided heating. The theoretical solution of the GTT model was validated by experimental data from intermediate-scale calorimeter fire tests of E-glass fiber reinforced polyester composite panels at three heat flux levels. The GTT model was also verified by results from finite element modeling predictions. Compared with the classical theoretical models (such as thermally thick (TTK) and thermally thin (TTN) models), the GTT model is more accurate and it is valid through the whole range of thermal thickness.

Since existing ignition criteria cannot handle the variations of external heat flux and surrounding environmental conditions, a new ignition criterion referred as Heating Rate-related Ignition Temperature (HRIT) criterion, was proposed, developed and validated. In the new HRIT ignition criterion both the surface temperature and its increasing rate are used to determine ignition. The accuracy of the HRIT ignition criterion under different external heat fluxes was validated by the piloted ignition data of a thermoplastic material (Black PMMA), a thermoset composite material (E-glass fiber reinforced polyester composite) and a cellulosic material (Red Oak) subjected to different external heat fluxes. The adaptability of the HRIT criterion in different surrounding environmental conditions was also discussed.

Both local and global sensitivity and uncertainty analyses were performed to understand the variations and identify important factors affecting the ignition process. First, the local sensitivity analysis was applied to the GTT model and the HRIT criterion separately. Then a Monte Carlo analysis using the Latin Hypercube Sampling method was performed on the integrated ignition prediction model (the GTT model combined with HRIT ignition criterion), yielding the global sensitivity coefficients (or important index) and uncertainty ranges of the ignition.

In summary, unlike classical temperature profile prediction models such as thermally thick or thermally thin models whose applications are restricted by thermal thickness, the new GTT model proposed in this research is valid within the whole range of thermal thickness. The challenge of the existing ignition criteria handling varying heat fluxes and surrounding environment was resolved by the new HRIT ignition criterion, and the accuracy of the HRIT criterion was validated by experimental data from three materials. The important affecting factors and uncertainties during ignition process were identified in this research through the uncertainty and sensitivity study, which can serve as a guideline for fire safety design

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Pratikakis, Nikolaos. "Mathematical modeling of rail gun." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Sep%5FPratikakis.pdf.

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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, September 2006.
Thesis Advisor(s): Kwon Young. "September 2006." Includes bibliographical references (p. 77-78). Also available in print.

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Rodríguez, Alvarado Juan Fernando. "Validation of a numerical model for the analysis of thermal-fluid behavior in a solar concentrator vessel." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59936.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 44).
The need for innovation in the renewable energy sector is an ever-growing concern. With national-level disasters in the Gulf of Mexico, the necessity to begin the drive to develop effective and practical alternative energy sources becomes a more pressing concern. The CSPond project is an attempt to design a more simple solar thermal energy generation system that additionally addresses the intermittence issue. The CSPond system calls for a large container in which special salt mixtures are molten by solar thermal energy. The large container also acts as a thermal energy storage to address the intermittence issue that has held back the widespread application of solar energy systems. This thesis presents a validation analysis of a numerical simulation of a molten salt system. The simulation is part of a larger design effort to develop a viable solar thermal energy option which incorporates short to medium-term thermal storage. To validate the numerical model, a scaled version of the proposed solar vessel was used in the solar simulator built by Professor Slocum's PERG to simulate normal operation procedures. This data was then compared to the numerical simulations. This comparison found that the numerical simulation does not capture the dynamics of the temperature rise in the system, but that it does capture the Rayleigh-Taylor instabilities, characteristic of convection. Solutions to the issues identified above are proposed and analyzed. These include the consideration of several modes of thermal interactions with the environment, the optical interactions between the solar beam and the molten salt medium, modifying the boundary conditions and finally, including the temperature of all relevant thermophysical properties to better capture the convective behavior of the molten salt system.
by Juan Fernando Rodríguez Alvarado.
S.B.

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Trunova, Olena. "Effect of thermal and mechanical loadings on the degradation and failure modes of APS TBCs." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=982570570.

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Reese, Gordon Scott. "Analytical Thermal Model of Friction Stir Welding with Spatially Distributed Heat Source." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3328.

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Friction stir welding (FSW) has been studied extensively for the past two decades. Thermal modeling has been of particular interest, as the quality of the weld is dependent upon the temperature history of the work piece during the process. Since direct temperature measurements of the welded zone are not possible, an analytical model was developed to predict the temperature in this area. This model requires parameters that cannot be easily experimentally determined, so a best fit for these parameters was acquired via regression analysis by comparing the model to experimental data acquired outside of the weld zone. The model was then validated by comparing it to additional temperature data, not including the data used for regression analysis.

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Fan, Guodong. "Model Order Reduction of Multi-Dimensional Partial Differential Equations for Electrochemical-Thermal Modeling of Large-Format Lithium-ion Batteries." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468917668.

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Topel, Monika. "Steam Turbine Thermal Modeling for Improved Transient Operation." Licentiate thesis, KTH, Kraft- och värmeteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156196.

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The growing shares of renewable energy sources in the market and solar thermal power applications have set higher requirements on steam turbine operation.These requirements are related to flexibility during transients. A key aspect sought of such flexibility is the capability for fast starts. Due to the varying temperature gradients during start-up, the speed at which the turbine can start is constrained by thermal stresses and differential expansion. These phenomena either consume component lifetime or may result in machine failure if not carefully controlled. In order to accomplish faster starts while ensuring that lifing requirements are preserved, it is important to analyze the thermal behavior of the machine. For this, a transient thermal model was developed with a focus on adaptability to different turbine sizes and geometries. The model allows for simple and fast prediction of thermo-mechanical properties within the turbine metal, more importantly, of the temperature distribution and the associated thermal expansion. The next step of this work was to validate the assumptions and simplifications of the model. This was done through the study and comparison of two turbines against measured operational data from their respective power plants. Furthermore,validation studies also included comparisons concerning the geometric detail level of the model. Overall, comparison results showed a large degree of agreement with respect to the measured data and between the geometric detail levels. The validated model was then implemented in studies related to reducing start-up times and peak differential expansion. For this, the potential effects of turbine temperature maintaining modifications were investigated and quantified.The modifications studied included: increasing gland steam pressure, increasing back pressure and increasing barring speed. Results yielded significant improvements starting from 9.5% in the start-up times and 7% in the differential expansion.

QC 20141128

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31

Guo, Ruilan. "Dependence of physical and mechanical properties on polymer architecture for model polymer networks." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22642.

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Thesis (Ph. D.)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Karl I. Jacob; Committee Member: Anselm C. Griffin; Committee Member: C. P. Wong; Committee Member: Rina Tannenbaum; Committee Member: William J. Koros; Committee Member: Yonathan S. Thio.

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32

Hall, James B. "Measurement of Thermal Diffusivities Using the Distributed Source, Finite Absorption Model." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3467.

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Thermal diffusivity in an important thermophysical property that quantifies the ratio of the rate at which heat is conducted through a material to the amount of energy stored in a material. The pulsed laser diffusion (PLD) method is a widely used technique for measuring thermal diffusivities of materials. This technique is based on the fact that the diffusivity of a sample may be inferred from measurement of the time-dependent temperature profile at a point on the surface of a sample that has been exposed to a pulse of radiant energy from a laser or flash lamp. An accepted standard approach for the PLD method is based on a simple model of a PLD measurement system. However, the standard approach is based on idealizations that are difficult to achieve in practice. Therefore, models that treat a PLD measurement system with greater fidelity are desired. The objective of this research is to develop and test a higher fidelity model that more accurately represents the spatial and temporal variations in the input power. This higher fidelity model is referred to as Distributed Source Finite Absorption (DSFA) model. The cost of the increased fidelity associated with the DSFA model is an increase in the complexity of inferring values of the thermal diffusivity. A new method of extracting values from time dependent temperature measurements based on a genetic algorithm and on reduced order modeling was developed. The primary contribution of this thesis is a detailed discussion of the development and numerical verification of this proposed new method for measuring the thermal diffusivity of various materials. Verification of the proposed new method was conducted using numerical experiments. A detailed model of a PLD system was created using advanced engineering software, and detailed simulations, including conjugate heat transfer and solution of the full Navier-Stokes equations, were used to generate multiple numerical data sets. These numerical data sets were then used to infer the thermal diffusivity and other properties of the sample using the proposed new method. These numerical data sets were also used as inputs to the standard approach. The results of this verification study show that the proposed new method is able to infer the thermal diffusivity of samples to within 4.93%, the absorption coefficient to within 10.57 % and the heat capacity of the samples to within 5.37 %. Application of the standard approach to these same data sets gave much poorer estimates of the thermal diffusivity, particularly when the absorption coefficient of the material was relatively low.

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Dickson, Matthew R. "Handheld infrared camera use for suicide bomb detection: feasibility of use for thermal model comparison." Thesis, Kansas State University, 2008. http://hdl.handle.net/2097/1045.

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Master of Science
Department of Mechanical and Nuclear Engineering
Akira Tokuhiro
One of the most deadly tactics used by today’s terrorists is suicide bombing. Sensors have been developed and are being used in different situations to detect weapons and the people initiating suicide bombing attacks. The ideal detection technology would be fast, accurate, effective from long distances, and safe for the both detector and the object being detected. One detector that has shown potential as a tool for detecting hidden weapons is an infrared detector. Infrared detectors are passive sensors that create infrared, or thermal, images without having to expose the subject to any radiation. These images show the heat signature that is given off by objects of interest. Previous studies using infrared detectors for concealed weapon detection have tried to observe the image of the weapon. These have been largely unsuccessful, however, because infrared waves will not readily penetrate clothing. The research presented here determines the feasibility of modeling the heat signature produced by a suicide bomber using thermal models that predict the temperature of the exterior layers of clothing worn. The goal is to be able to compare the images acquired of the suspected bomber to the expected temperatures from the thermal models. If the presence of a hidden weapon affects the emitted heat signature to a point in which the clothing temperatures are not responding as predicted by a model, it is possible a detection system may be created using these models as a comparator and signal for detection. This research also determines a temperature range for which an operator viewing infrared images for suicide bomb detection may be relatively certain of the presence of a foreign object. Testing was also completed to determine those variables that affect an infrared image in ways that help or hinder the use of the thermal models in predicting the temperatures that appear in the infrared images.

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Dalke, Phillip Allen. "Model-Based Design and Analysis of Thermal Systems for the Ohio State EcoCARMobility Challenge Vehicle." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu159545443238678.

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Singh, Naveen Chandra Lall Pradeep. "Thermo-mechanical reliability models for life prediction of area array electronics in extreme environments." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/master's/SINGH_NAVEEN_54.pdf.

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Nuzum, Sean Robert. "Aircraft Thermal Management using Liquefied Natural Gas." Wright State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=wright1462460693.

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37

Caliguri, Ryan P. "Comparison of Sensible Water Cooling, Ice building, and Phase Change Material in Thermal Energy Storage Tank Charging: Analytical Models and Experimental Data." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627666292483648.

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38

Antón, Remírez Raúl. "Experimental and numerical study of the thermal and hydraulic effect of EMC screens in radio base stations : detailed and compact models." Doctoral thesis, KTH, Energiteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4265.

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Today’s telecommunication cabinets use Electro Magnetic Compliance (EMC) screens in order to reduce electromagnetic noise that can cause some miss functions in electronic equipment. Many radio base stations (RBSs) use a 90-degree building architecture: the flow inlet is perpendicular to the EMC screen, which creates a complex flow, with a 90-degree air turn, expansions, compressions, perforated plates and PCBs. It is of great interest to study how the EMC screen interacts with the rest of components and analyze the total pressure drop and how much the flow pattern changes due to the placement of the screen. Velocity, pressure and temperature measurements as well as flow pattern visualizations have been carried out to gain good insight into the flow and heat transfer characteristics in a subrack model of an RBS. Furthermore, these measurements have been very useful for validating detailed CFD models and evaluating several turbulence models. Nowadays, industrial competition has caused a substantial decrease in the time-to-market of products. This fact makes the use of compact models in the first stages of the design process of vital importance. Accurate and fast compact models can to a great extent decrease the time for design, and thus for production. Hence, to determine the correlations between the pressure drop and flow pattern on the PCBs as a function of the geometry and the Reynolds number, based on a detailed CFD parametric study, was one objective. Furthermore, the development of a compact model using a porous media approach (using two directional-loss coefficients) has been accomplished. Two correlations of these directional loss coefficients were found as a function of the geometry and Reynolds number.
QC 20100630

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Filipovic-Gledja, Visnja. "A probability based unified model for predicting electrical, mechanical and thermal characteristics of stranded overhead-line conductors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30086.pdf.

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40

Ezeanya, Emeka K. "System Advisor Model (SAM) Simulation Modeling of a Concentrating Solar Thermal Power Plant with Comparison to Actual Performance Data." Thesis, University of Louisiana at Lafayette, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10642898.

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This thesis focused on the modeling and simulation of a 50 kW Concentrating Solar Power (CSP) plant, which is located in Crowley, Louisiana. The model was developed using System Advisor Model (SAM), which is software created by the National Renewable Energy Laboratory (NREL) for modeling and analyzing different renewable energy systems. The objective of this thesis is to develop a predictive model (using SAM) that will characterize the performance of the power plant and, thus, aid the analysis and evaluation of the plant’s performance. The power plant is a research facility of the Solar Thermal Applied Research and Testing (START) Lab. This facility is focused on the development and deployment of renewable energy systems, exploring solar power options in Louisiana, and providing insight into solar power development across different locations. The power plant uses water as its Heat Transfer Fluid (HTF). Part of the design constraint for the model is the low temperature requirement for the power cycle (88 °C–116 °C). Because the basic ORC model of SAM does not support this low temperature range, a custom power cycle was modeled using the user-defined power cycle option of SAM. Other characteristics and controls of the plant were also properly defined. The model was validated by comparing its predictions with the actual plant data. This comparison showed a good correlation between the predicted results and the actual plant data. The validated model was then used to perform parametric analyses across different locations. The analyses showed that by operating the power plant at the optimal combination of solar multiple and hours of storage, we can achieve about 70% reduction in the cost of electrical energy, which is, indeed, a significant cost reduction.

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Narvaez, Javier A. "Thermal Conductivity of Poly-Alpha-Olefin (PAO)-Based Nanofluids." University of Dayton / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1282162148.

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42

Fossier, Charlotte. "Investigations on the efficiency of truck axles and their hypoid gear set : A thermo-mechanical model." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI019.

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Pour répondre au besoin des clients ainsi qu’aux réglementations gouvernementales, les constructeurs de camions doivent diminuer la consommation et les émissions de leurs véhicules. Une solution-clé est d’améliorer le rendement de la transmission du camion, dont le pont fait partie. Leur design n’a longtemps été optimisé qu’en fonction de critères de durabilité et de bruit. L’objectif de ce travail est donc de caractériser le rendement des ponts de camion. La dissipation de puissance au sein du pont est causée par l’engrènement, les roulements, les joints et le barbotage. Des méthodes permettent d’estimer globalement ces pertes de puissance, mais elles ne sont pas forcément adaptées aux ponts. En effet, l’élément principal du pont est un engrenage spiro-conique ou hypoïde et son importance est étudiée : sa forme influe sur le barbotage, tandis que sa géométrie de denture et sa cinématique gouvernent le frottement à l’engrènement. Il semble ainsi important d’évaluer le frottement de ces couples coniques par une approche locale et d’étudier l’influence des paramètres de denture. Cependant, les pertes de puissance dépendent de la température, via les propriétés de l’huile. Des expériences montrent un important écart de température entre les composants. Il faut donc considérer des températures locales plutôt qu’une température d’huile globale. Le rendement et la durabilité peuvent être impactés par des points chauds. La méthode des réseaux thermiques permet de modéliser les échanges thermiques du pont ainsi que la distribution de températures. Les tests classiques de rendement mesurent uniquement la perte globale et la température d’huile : rien ne permet de confirmer la répartition des pertes entre sources. Une campagne d’essais avec mesures de température est donc réalisée et valide le modèle pour le calcul des températures locales et pour l’estimation des pertes de chaque composant. Ce modèle peut alors être utilisé lors du design de futurs ponts
To fulfil customer demands, but also government regulations, the truck industry must decrease the fuel consumption and emissions of its vehicles. A key development is to improve the efficiency of the powertrain, which includes the axle. Until recently, optimisation of axle design has mainly concerned durability and noise aspects. The aim of this study is then to characterise the efficiency of truck axles. As for most of the mechanical transmissions, power dissipation in axles is due to gear mesh, rolling element bearings, seals and oil churning. Formulae already exist to estimate these power losses at a global level, but they are not always adapted to axles. Indeed, the main component of axles is a spiral bevel or a hypoid gear set. The influence of these special gears on efficiency is investigated here: their shape drives oil churning losses, while their tooth geometry and their kinematics impact friction at gear mesh. Therefore, the meshing friction of the gear set is also evaluated thanks to a local approach. The influence of some gear parameters is studied. However, power losses are influenced by temperature through oil viscosity. As previous experiments underline non-negligible temperature difference between components, it is necessary to consider local temperatures instead of a global oil temperature. Efficiency but also durability can be impacted by local hot spots. The thermal network method is used to model the thermal exchanges inside and outside the axle and to calculate temperature distribution. Usual efficiency tests on axles measure only global power loss and oil temperature: no evidence allows to confirm a power loss breakdown. Thus, a test campaign with temperature measurements is done and validates the model on local temperature calculation but also on estimation of component power losses. The model can be used at design stage for future development of axles

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43

Hatzenbuehler, Mark A. "Modeling of jet vane heat-transfer characteristics and simulation of thermal response." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23314.

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Approved for public release; distribution is unlimited
The development of a dynamic computational model capable of predicting, with the requisite design certainty, the transient thermal response of jet vane thrust control systems has been undertaken. The modeling and simulation procedures utilized are based on the concept that the thermal processes associated with jet vane operation can be put into a transfer function form commonly found in the discipline of automatic controls. Well established system identification methods are employed to formulate and verify the relationships between the various gains and frequencies of the transfer function model and experimental data provided by Naval Weapons Center, China Lake.
http://archive.org/details/modelingofjetvan00hatz
Lieutenant, United States Navy

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Rodríguez, Buño Mariana. "Near and far field models of external fluid mechanics of Ocean Thermal Energy Conversion (OTEC) power plants." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/79495.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 126-130).
The world is facing the challenge of finding new renewable sources of energy - first, in response to fossil fuel reserve depletion, and second, to reduce greenhouse gas emissions. Ocean Thermal Energy Conversion (OTEC) can provide renewable energy by making use of the temperature difference between the surface ocean and deep ocean water in a Rankine cycle. An OTEC plant pumps huge volumes of water from the surface and nearly 1 km depth, and releases it at an intermediate depth. The effects of this enormous flux are crucial to understand since disruption of the ambient temperature stratification can affect the efficiency of the plant itself and of adjacent plants. This thesis aims to study the external fluid mechanics of offshore OTEC power plants, to assess their environmental impact and to help analyze whether OTEC plants can provide a sustainable source of energy. Although there has been interest in OTEC for several decades, so far primarily physical and analytical models have been developed. In this study numerical models are developed to model OTEC operating plants: integral models for the near and intermediate field and a large-scale ocean general circulation model. Two strategies in modeling OTEC plant discharge are used to analyze plume dynamics: the "Brute Force" approach, in which a circulation model, MITgcm, computes the near, intermediate and far field mixing; and the "Distributed Sources and Sinks" approach, in which the near and intermediate field are represented in the circulation model by sources and sinks of mass computed by integral models. This study concludes that the Brute Force modeling strategy is highly computationally demanding and sometimes inaccurate. Such simulations are very sensitive to model resolution and may require the use of unrealistic model parameters. The Distributed Sources and Sinks approach was found to be capable of modeling the plume dynamics accurately. This method can be applied to the study of adjacent OTEC power plant interaction, redistribution of nutrients, and propagation of contaminants.
by Mariana Rodríguez Buño.
S.M.

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SAMPATH, KUMAR RAGHAV. "NUMERICAL, EXPERIMENTAL AND ANALYTICAL STUDY OF THERMAL HEATING OF SPHERE AND DISK SHAPED BIOCRYSTALS EXPOSED TO 3 ^RDGENERATION SYNCHROTON SOURCES." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155103284.

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46

Massé, Danielle D. "Effects of Lubrication Starvation on Flash Temperature for Thermal Mixed Elastohydrodynamic Gear Contacts." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1574433184018376.

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Potdar, Akshay Anand. "Reducing the uncertainty of thermal model calibration using on-machine probing and data fusion." Thesis, University of Huddersfield, 2016. http://eprints.hud.ac.uk/id/eprint/31397/.

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Abstract:

Various sources of error hinder the possibility of achieving tight accuracy requirements for high-value manufacturing processes. These are often classified as: pseudo-static geometric errors; non-rigid body errors; thermal errors; and dynamic errors. It is comparatively complicated to obtain an accurate error map for the thermal errors because they are influenced by various factors with different materials, time constants, asymmetric heating sources and machining process, environmental effects, etc. Their transient nature and complex interaction mean that they are relatively difficult to compensate using pre-calibration methods. For error correction, the magnitude and sign of the error must first be measured or estimated. Pre-calibrated thermal compensation has been shown to be an effective means of improving accuracy. However, the time required to acquire the calibration data is prohibitive, reducing the uptake of this technology in industrial applications. Furthermore, changing conditions of the machine or factory environment are not adequately accommodated by pre-calibrated compensation, leading to degradation in performance. The supplementary use of on-machine probing, which is often installed for process control, can help to achieve better results. During the probing operation, the probe is carried by the machine tool axes. Therefore, the measurement data that it takes inevitably includes both the probing errors and those originating from the inaccuracies of a machine tool as well as any deviation in the part or artefact being measured. Each of these error sources must be understood and evaluated to be able to establish a measurement with a stated uncertainty. This is a vital preliminary step to ensure that the calibration parameters of the thermal model are not contaminated by other effects. This thesis investigates the various sources of measurement uncertainties for probing on a CNC machine tool and quantify their effects in the particular case where the on-machine probing is used to calibrate the thermal error model. Thermal errors constitute the largest uncertainty source for on-machine probing. The maximum observed thermal displacement error was approximately 220 μm for both X and Z-axis heating test at 100 % speed. To reduce the influence of this uncertainty source, sensor data fusion model using artificial neural network and principal component analysis was developed. The output of this model showed better than 90 % correlation to the measured thermal displacement. This data fusion model was developed for the temperature and FBG sensors. To facilitate the integration of the sensor and to ease the communication with machine tool controller, a modular machine tool structural monitoring system using LabVIEW environment was developed. Finally, to improve the performance of the data fusion model in order to reduce the thermal uncertainty, a novel photo-microsensor based sensing head for displacement measurement is presented and analysed in detail. This prototype sensor has measurement range of 20 μm and resolution of 21 nm.

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Khasawneh, Hussam Jihad. "ANALYSIS OF HEAT-SPREADING THERMAL MANAGEMENT SOLUTIONS FOR LITHIUM-ION BATTERIES." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313603207.

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Huang, Zhida. "SIMULATION OF METAL GRAIN GROWTH IN LASER POWDER BED FUSION PROCESS USING PHASE FIELD THERMAL COUPLED MODEL." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1554391043588225.

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Manasrah, Ahmad. "Application and Analysis of Asymmetrical Hot and Cold Stimuli." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6309.

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The human body has a unique mechanism for perceiving surrounding temperatures. When an object is in contact with the skin, we do not feel its temperature. Instead, we feel the temperature change that is caused on our skin by that object. The faster the heat is transferred, the more intense the thermal sensation is. In this dissertation, a new dynamic thermal display method, where different rates of warm and cold are applied on the skin to generate a unique sensation, is presented. The new method can be related in a wide range of applications including thermal haptics and virtual reality. To understand the perception of temperature and the general thermal state of the human body, the first aspect of this dissertation focuses on investigating the interaction between temperature change and perception on a large scale. Three field surveys were conducted inside airconditioned buildings to investigate the change in the thermal state and temperature perception of occupants when the room temperature changes. The results showed that the participants’ prediction of constant operating temperature was poor, however, their prediction was significantly improved when temperature changes were presented. In order to more accurately investigate the perception of temperature on the skin, a new thermal display method using multiple-channel thermal actuators was developed. The principle of this method is to apply slow and fast rates of temperature change simultaneously on the skin. The slowly changing temperatures are below the perceptual threshold of the thermal receptors, therefore will not be detected whereas the quickly changing temperatures are above the perceptual threshold, hence, will be detected. The idea here is to keep the average surface temperature of the skin constant, however a person will perceive a sensation of continuous cooling. This method was tested through a series of experiments, and the results showed that it is capable of generating a continuous cooling sensation without changing the average temperature of the stimulation area. Multiple variations of this method were tested including different heating and cooling rates of change, different skin locations and patterns of stimuli. Also, a continuous warming was generated using similar concept. To further investigate the temperature distribution that is caused by this method and its effect on the skin, a computational simulation was conducted. An approximate model of the skin was used to monitor its surface temperature and record the temperatures in the stimulation area when the continuous cooling method is applied. The results of the simulation showed that the temperature under the surface of the stimulation area was affected by the continuous cooling method that was applied on the skin model, however this method did not affect the average surface temperature of the skin. These findings may later determine the efficiency and intensity of the method of continuous cooling, and allow us to investigate different technically challenging variations of this method.

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Dissertations / Theses on the topic 'Thermal and mechanical models'

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