Dissertations / Theses on the topic 'Composite materials – Moisture'
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Davison, Sneha Patel. "Enviro-Mechanical Durability of Graphite/Epoxy Composite Materials." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/11087.
Full textPh. D.
Ryan, Joanne Maureen. "Relating moisture ingress to component strength and stiffness for carbon-fibre composites." Thesis, Swansea University, 2011. https://cronfa.swan.ac.uk/Record/cronfa42389.
Full textWang, Zhiqiang. "Transient moisture effects on the viscoelasticity of synthetic fibers and composites." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39695.
Full textEarl, Jacqueline Sonia. "The influence of hygrothermal ageing on polymeric composite sandwich materials and structures." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342836.
Full textTai, David Seechung. "A new model of moisture evaporation in composite materials in rapid temperature rise environments." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/49920.
Full textCheng, Qingzheng. "Microstuctural Changes in Wood-Plastic Composites (WPC) Due to Extended Moisture Cycling and its Relationship to Mechanical Performance Changes." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/ChengQ2005.pdf.
Full textEyre, Kyle J. "Moisture absorption and stiffness degradation of carbon fiber reinforced polymer composite specimens exposed to accelerated environmental aging conditions." Laramie, Wyo. : University of Wyoming, 2007. http://proquest.umi.com/pqdweb?did=1313919681&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
Full textТомас, А. А., and Л. И. Гутенко. "Причины и способы устранения проблемы влагопоглощения в композиционных материалах на основе ПТФЭ и УВ." Thesis, Издательство СумГУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/8267.
Full textRoy, Samit. "A finite element analysis of adhesively bonded composite joints including geometric nonlinearity, nonlinear viscoelasticity, moisture diffusion and delayed failure." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/88624.
Full textDoctor of Philosophy
Musaramthota, Vishal. "Prediction of Fracture Toughness and Durability of Adhesively Bonded Composite Joints with Undesirable Bonding Conditions." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2513.
Full textBuck, Stephanie E. "Combined effects of moisture, temperature, fiber architecture, and sustained load on the mechanical and microstructural properties of notched and unnotched e-glass/vinyl ester composite materials /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9952663.
Full textBudhe, Sandip Rudha. "Effect of pre-bond moisture on the static and fatigue behaviour of bonded joints between CFRP laminates for structural repairs." Doctoral thesis, Universitat de Girona, 2014. http://hdl.handle.net/10803/283567.
Full textDurant els últims anys, la utilització de materials compòsits en la indústria aeronàutica, automoció, construcció marina, etc. ha tingut un gran creixement. Es per aquesta raó, que cada vegada té més importància el desenvolupament de mètodes per a la seva reparació, i especialment la definició mètodes de reparació en components que realitzen una funció estructural, doncs la substitució del component no és econòmicament viable en molts dels casos. És un fet conegut, que les estructures de material compòsit en condicions de servei pateixen danys provocats per impactes accidentals, tensions mecàniques, efectes ambientals (humitat i temperatura), etc. Per tant, el manteniment i la reparació d’aquestes estructures són considerats processos de vital importància per a l’usuari final i també per als fabricants. Una bona tria dels materials, així com un bon control dels processos de curat, tenen un gran efecte en l’obtenció de reparacions fiables. En aquest treball s’ha analitzat l’efecte la l’absorció de la humitat en el substrat abans del procés de curat en unions co-encolades sotmeses a càrregues estàtiques i de fatiga. L’anàlisi s’ha dut a terme amb provetes amb 3 nivells d’absorció d’humitat (0%, 0.33% y 1.25%) i dos tipus d’adhesius laminats (F1 i F2)
Réquilé, Samuel. "De la plante aux biocomposites : caractérisation des interfaces multiples et étude des paramètres pertinents Exploring the link between flexural behaviour of hemp and flax stems and fiber stiffness Peeling experiments for hemp retting characterization targeting biocomposites Deeper insight into the moisture-induced hygroscopic and mechanical properties of hemp-reinforced biocomposites. Interfacial properties of hemp fiber/epoxy: effect of moisture sorption and induced hygroscopic stresses Propriétés hygroscopiques et mécaniques d'un biocomposite renforcé par des fibres de chanvre." Thesis, Lorient, 2019. http://www.theses.fr/2019LORIS529.
Full textIndustry environmental concerns and strategies to become part of a more sustainable economic system, leads to a growing interest in research on biocomposite. The strong polar and hydrophilic nature of plant fibers leads, when used as a reinforcement, to a complexity of biocomposite manufacturing and limits in terms of load transfer at the fiber/matrix interface. These major locks (fiber polarity and moisture sensitivity) for biocomposites development are the guidelines of this thesis work taking its inspiration in the design of hemp stem tissue interfaces. The multi-scale evolution of gradient microstructure and internal mechanics is crucial for the integrity and functioning of the stem through smooth transitions regions. These potential weak interfaces are investigated by applying a retting process that affect the stem internal microstructure and tissue cohesion. From the stems of agricultural crops to the hierarchical elementary fibers, studying the mechanical behavior of natural systems may serve as inspiration for a biomimetic transfer of the fundamental principles to fiber-reinforced composites. Aimed at increasing the understanding of the effect of moisture present during composite use, hygro-mechanical coupling highlights an optimum in hemp fibre-based unidirectional composites performances from a beneficial effect of moisture sorption. Deeper analysis at the micro-scale attributed a significant contribution of this hygroscopic behavior to fiber/matrix interface performances through the creation of residual stresses and capillary adhesion mechanisms. Generally described in the literature as a drawback, this research demonstrates that water sensitivity of plant fibers and moisture sorption in biocomposite could promote load transfer and be beneficial for their performance
Strömbro, Jessica. "Micro-mechanical mechanisms for deformation in polymer-material structures." Doctoral thesis, KTH, Hållfasthetslära (Inst.), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4626.
Full textQC 20100910
Kock, Jeffrey Wayne. "Physical and Mechanical Properties of Chicken Feather Materials." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10555.
Full textMárquez, Costa Juan Pablo. "Caractérisation et modélisation des interfaces dans les composites organiques stratifiés à haute température : Application à la tenue au feu des structures aéronautiques PhyFire LOT 2 - Développement de modèles de comportement du composite Caractérisation en température de la ténacité en mode II des interfaces des CMO en utilisant l’effet Joule Caractérisation du comportement visqueux des interfaces CMO et influence sur la propagation de délaminage Convention PhyFIRE 2 - LOT 2 : Développement d’un cadre de modélisation pour les matériaux composites Durabilité des matériaux composites en conditions extrêmes : vers la prédiction des propriétés de tenue au feu Durability of Composite Materials under Severe Temperature Conditions : Influence of Moisture Content and Prediction of Thermo- Mechanical Properties During a Fire Towards the Prediction of Sandwich Composites Durability in Severe Condition of Temperature : A New Numerical Model Describing the Influence of Material Water Content during a Fire Scenario." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2021. http://www.theses.fr/2021ESMA0004.
Full textWithin the framework of the fire resistance of composite materials, it is necessary to assess the degradation of their thermal and mechanical properties due to mass losses, matrix cracking and/or delamination cracks. Nevertheless, few studies in the literature about the temperature resistance of aeronautical composites concern the mechanical behaviour and the rupture of interfaces before any thermal degradation,subject which is the main topic of this work. Thus, the objective is to propose a failure model concerning both the delamination crack initiation and growth under thermomechanical loads. Much of this work has focused on the characterisation of interface properties using an analysis of mode II crack propagation tests for Joule heated specimens. These numerical analyses show that the ply behaviour does not explain the macroscopic pseudo-ductile response observed experimentally. Thus, a test-calculation dialog method, comparing the kinematic fields measured by digital images correlation and those simulated by finite elements, underlines the importance of the viscous behaviour at the interface scale. By a similar FEMU approach the parameters of a cohesive-type fracture law have been identified in temperature and taking into account the different sources of uncertainty. This work highlights the similarity between plane and out-of-plane shearing, both on behaviour and on failure. In parallel, the analysis of temperature resistance tests by laser impact made it possible to establish a crack initiation criterion by a coupled stress and energy approach. A comparison of this criterion with the parameters of the cohesive zone law previously identified makes it possible to discuss about the modeling scale of the interface
Ripoll, Masferrer Lluís. "Análisis y diseño de volantes de inercia de materiales compuestos." Doctoral thesis, Universitat Politècnica de Catalunya, 2006. http://hdl.handle.net/10803/6415.
Full textSe desarrolla un sistema analítico de cálculo muy completo, tanto en las cargas como en las tensiones. Se consideran todas las cargas necesarias para el diseño mecánico del rotor: la fuerza centrífuga, la fuerza de aceleración y las tensiones residuales, térmica y de hidratación; y se determinan todas las componentes, normales y cortantes, de la tensión para cada punto del rotor.
El cálculo en condiciones de tensión plana, utilizado por la mayoría de autores, se amplía con el cálculo en deformación axial constante, que es una variante mejorada de la deformación plana. Se comprueba que sus resultados son mejores que los de tensión plana cuando se comparan con los obtenidos en modelos de elementos finitos. Paralelamente, como aportación nueva de la tesis, se deducen las funciones de la variación de la tensión axial y de la tensión cortante radial-axial a lo largo del eje longitudinal del rotor. A partir de estos resultados se desarrolla un sistema general de cálculo que, además de unificar los sistemas de tensión plana y deformación axial constante, permite determinar todas las tensiones en cualquier posición radial-axial del rotor.
Este sistema unificado de cálculo se amplia con tres particularidades: una aplicación de cálculo para resolver rotores multicapa, las ecuaciones especiales para los materiales singulares no resolubles con las ecuaciones generales, y el cálculo de capas con fibras orientadas axialmente aplicadas para refuerzo en configuraciones especiales.
Con el objeto de mejorar las prestaciones del rotor se estudian dos procedimientos para crear tensiones de pretensado: generando tensiones durante el bobinado y utilizando las tensiones residuales térmicas. En el primero se elabora un sistema analítico de cálculo para determinar las tensiones residuales de bobinado y se complementa con una simulación mediante elementos finitos basada en submodelos incrementales. Ambos cálculos son capaces de simular el material no curado aplicando las propiedades viscoelásticas de los ensayos experimentales de otros autores. En el segundo se presenta un sistema nuevo, denominado pretensado térmico, basado en el curado por etapas, que genera tensiones residuales parecidas a las de bobinado pero con menos problemas de fabricación.
El diseño de volantes se aplica a tres configuraciones básicas: rotores híbridos multicapa con materiales de rigidez progresiva, rotores de un solo material con anillos de elastómero y rotores con pretensado térmico.
Sus prestaciones se valoran con tres variables: la masa, el volumen y el coste del material; de las cuales el coste es la principal y se utiliza para la optimización de la geometría.
En cada configuración se determina la energía máxima para distintas relaciones de radios del rotor y se compara con el rotor de un sólo material. Se utilizan los materiales básicos usados en la fabricación de rotores: la fibra de carbono con matriz epoxi, la fibra de vidrio con matriz epoxi, el aluminio y el acero. Los dos materiales compuestos ofrecen mejores resultados que los metales, pero disminuyen sensiblemente en rotores con espesor de pared grande. En estos casos, la energía por unidad de coste mejora aplicando los anillos elásticos y el pretensado térmico.
Flywheels are better than electric batteries in that they absorb and yield energy in shorter time and, if made out of composite materials, also in that they weight less. This thesis presents a study of composite material rotors applied to kinetic accumulators in order to make them usable for low cost general industrial uses. Two objectives are proposed: a) to develop an analytical system for computation and b) to design alternatives in order to improve the performance on low-cost rotors.
The analytical system is intended to be very complete, considering all relevant types of external loads and stress components. For the former, centrifugal, acceleration forces and residual, thermal and moisture stresses are included. For the latter, five normal and shear components are computed at each point of the rotor.
The usual plane stress condition is expanded with the consideration of constant axial strain, along the lines of the plane strain hypothesis but with greater accuracy. It is shown that the current theory results fit the ones from finite elements much better than those from plain stress. As a new contribution, the functions for the axial stress and the radial-axial stress along the axis of the rotor are developed. From these results, a general system that unifies the plane stress and constant axial strain can compute the stress state at any position.
In addition, the unified system includes three novel aspects: an extension of computation for multi-layer rotors, special equations for some materials in which behaviour present singularities and the computation of layers with fibers along the axial direction, which can be useful as a reinforcement for some configurations.
Two procedures that can create beneficial residual stresses are studied: generating stresses during the filament winding and using the thermal stresses. For the first, analytical expressions are developed and validated and complemented with especially developed finite elements based on incremental submodels. In both cases the material is characterized by viscoelastic properties taken from the literature. For the second, a new procedure called thermal prestress is based on the accumulation of partial curing processes (by stages), which is able to create residual stresses similar to those of winding but involving simpler manufacturing.
Three basic configurations are studied for the design: hybrid rotors with progressive stiffness along the radius, single material rotors with elastomer thin rings and rotors manufactured with thermal prestress, evaluating the performance as a function of the mass, volume and cost of the material. The latter is defined as the most important, and it is used as a reference for the geometry optimization.
The maximum energy stored on each of the configurations is compared with that of a single material rotor, using the most common ones: glass and carbon fiber both with epoxy matrix, aluminium and steel. Results show that glass/epoxy has the highest storing capability per unit cost, although the number is greatly reduced when the thickness increases. If this rotor has a thin layer of carbon/epoxy, the capability does not increase, although it does with distributed elastomeric layers. There is also an increase with fabrication based on the thermal prestress technique.
Sayman, Sumeyra. "Analysis Of Fiber Reinforced Composite Vessel Under Hygrothermal Loading." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/1026376/index.pdf.
Full textChen, Chung-Yu, and 陳忠煜. "Low moisture absorption and low warpage characteristic of transparent panel composite materials research." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/7m8agk.
Full text國立臺北科技大學
有機高分子研究所
102
With the progress of science and technology, People have already to pursuit of light, thin, short, small requirement and applied to portable electronic products design. Therefore, the using of plastic material to replace the traditional glass products which used as a display substrate seems to have become an inevitable trend of development of this technology. However, when the production of plastic materials as the substrate components, size stability is due to the plastic substrate susceptible from external environmental factors (such as temperature and humidity ), that change arising from factors and resulting in restrictions on using of plastic substrates. For examples of the heat shrinkage rate, coefficient of linear expansion and coefficient of moisture expansion of the plastic substrate are larger than the glass. The Linear expansion coefficient of the glass is 8 * 10-6m/mK, almost negligible state; now be known the panel element is often used as the material of PMMA material having a linear expansion coefficient of 85 * 10-6m/mK, consequently the humidity and heat by the environment impact is even more remarkable, so if only using a PMMA substrate material is unable to improve this poor size stability shortcomings. The research, using two types of plastic materials and multi-layer extrusions lamination process system make the plates. Testing of this composite materials plate, the test items were followed the current industry up for plastic panel testing standards, such as optical properties, surface pencil hardness, falling ball drop impact test, moisture absorption test, heat shrinkage resistance test. All of experimental results show this composite material has a low moisture absorption rate, low warpage characteristic and the light transmittance can be achieved with similar PMMA substrate. Furthermore it also has flexibility and great impact resistance that is greater than the glass substrate material so can replace the proposed material as glass.
Saravanan, S. "Moisture Barrier Polymer Nanocomposites for Organic Device Encapsulation." Thesis, 2016. http://etd.iisc.ernet.in/2005/3809.
Full textLee, Sang Ick. "Development of Approach to Estimate Volume Fraction of Multiphase Material Using Dielectrics." 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-05-7578.
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