Tesis sobre el tema "Viscoelastic"
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Ruas, Henriques Isadora. "Analysis, characterization and modeling of viscoelastic and poro-viscoelastic materials". Thesis, Paris, HESAM, 2020. http://www.theses.fr/2020HESAC044.
Texto completoThis thesis deals with the modeling and characterization of the thermomechanical behavior of viscoelastic and poro-viscoelastic materials. The work is divided into two main parts: one concerning the experimental technique Dynamic Mechanical Analysis (DMA) and the other related to the damping performance of poro-viscoelastic materials. In the first part, the viscoelastic property known as complex modulus measured by the flexural modes of DMA is deeply examined theoretically and experimentally. Special attention is paid to the effects of operational modes and machines on various properties. Aiming to obtain a better analysis of the impacts of the discrepancies found, fractional derivative models (FDM) are calibrated within the Bayesian framework. Results show that DMAs have a great variability between modes or manufacturers and statistical models may mitigate these issues. In the second part, the dissipation of mechanical energy inherent to the viscoelasticity of three different porous materials is explored in the low-frequency range. Initially, a numerical approach is proposed to generate predictions in the time domain of the hysteretic behavior of the analyzed materials under different loading conditions. Then, a finite element model that considers a FDM is proposed to describe the behavior of simply supported panels covered with a free-layer of porous material. Experiments are carried out to validate the proposed model. Finally, an inverse method based on Bayesian inference was presented to identify the viscoelastic properties of these materials from vibration tests. The results of these analyses showed the great potential of poro-viscoelastic materials to be applied to damp mechanical vibrations
Lin, Kuanchung J. "Modeling viscoelastic jets /". The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487594970651388.
Texto completoInch, Scott E. "Precise energy decay rates for some viscoelastic and thermo-viscoelastic rods". Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39978.
Texto completoPh. D.
Tang, Bin. "Nanoindentation of viscoelastic materials". Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B3655408X.
Texto completoAtsbha, Hailemariam. "Viscoelastic flows around spheres". Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/7909.
Texto completoJohnson, Mitchell A. "Viscoelastic Roll Coating Flows". Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/JohnsonMA2003.pdf.
Texto completoMessalti, Mansour. "Viscoelastic damping of beams /". Online version of thesis, 1988. http://hdl.handle.net/1850/10414.
Texto completoTang, Bin y 唐斌. "Nanoindentation of viscoelastic materials". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B3655408X.
Texto completoJUNIOR, WALTER MENEZES GUIMARAES. "BUCKLING OF VISCOELASTIC STRUCTURES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2006. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9164@1.
Texto completoEste trabalho apresenta um modelo computacional aplicável à análise de sistemas estruturais viscoelásticos submetidos a grandes deslocamentos, com particular atenção ao fenômeno da instabilidade. A discretização dos modelos é obtida através de elementos finitos isoparamétricos bidimensionais que podem ser empregados na análise de colunas, pórticos, arcos e cascas axissimétricas. A estabilidade elástica do sistema é verificada ao longo de trajetórias de equilíbrio definidas no espaço carga-deslocamentos, onde a ocorrência de pontos de bifurcação ou de pontos-limite é indicada através da troca de sinal do pivô da matriz de rigidez tangente. A inclusão de um modelo viscoelástico linear para o material possibilita a avaliação do efeito do tempo de carregamento sobre a carga de flambagem da estrutura. O mecanismo de instabilidade correspondente à flambagem viscoelástica envolve duas variáveis básicas: a magnitude da carga (carga crítica) e a duração da carga (tempo crítico). Os exemplos apresentados ilustram esses conceitos e fornecem resultados interessantes a respeito dos efeitos da viscoelasticidade sobre a flambagem em diferentes sistemas estruturais.
This thesis presents a computational model for the analysis of viscoelastic structures undergoing large displacements, with particular attention to unstable phenomena. The discrete model utilizes two-dimensional isoparametric finite elements in the analysis of columns, frames, arches and axially symmetric shells. The elastic stability of the system is verified along the equilibrium paths in the multidimensional load-displacements space, with bifurcation or limit points indicated by sign changes of the pivot of the tangent stiffness at every incremental step. A linear viscoelastic model for the material is included, allowing for the consideration of the effect of loading time on the buckling load for the structure. Thus, the mechanism leading to loss of stability, corresponding to viscoelastic buckling, involves two basic variables: load magnitude and duration of the load, designated as critical load and critical time. The examples presented herein enlighten such concepts and provide interesting results about viscoelastic effects on buckling of different structural systems.
Ramsay, John Andrew. "Mixing of viscoelastic fluids". Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7333/.
Texto completoSantade, Fransber [UNESP]. "Análise dinâmica do amortecimento em estruturas compostas com material viscoelástico". Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/97030.
Texto completoNeste trabalho foi proposto o estudo do amortecimento estrutural em vigas engastadas com adição de materiais viscoelásticos. As vigas foram montadas na condição engastada-livre e sujeitas de força na extremidade livre. Duas análises foram feitas. O primeiro modelo foi desenvolvido utilizando a Matriz de Impedância de Elemento Espectral (MEE) e o outro modelo foi desenvolvido utilizando Método dos Elementos finitos (MEF). Para validar os modelos numéricos foram realizados ensaios experimentais utilizando um acelerômetro e um martelo de impacto para obter a função de resposta em frequencia para as diferentes configurações de vigas idealizadas. Através dos resultados obtidos pode-se observar e comprovar o comportamento com frequencia de resposta do sistema e detectou-se redução de amplitude devido ao fator incremental de amortecimento viscoelástico proporcionado pelas camadas de fita (materiais viscoelásticos), comprovando assim, a importância da utilização de um material viscoelástico como atenuador de amplitudes no efeito da flexão do sistema. Os resultados experimentais foram comparados aos resultados dos modelos analíticos e numéricos de modo a se obter a validação experimental
This work proposes the study of structural damping in beams with added viscoelastic materials. The beams are mounted in a clamped-free condition and subject to force input at the free end. Two types analisis were made. The first model was developed using the Impedance Matrix of Spectral Element. The other model was developed using Finite Element Method (FEM). To validate the numerical models, experimental tests were performed using one accelerometer and a impact hammer to obtain frequency responce function of the diferente beams configurations. From the results we can observe and verify the variation in frequency response of the system and was detected amplitude reduction factor due to the incremental viscoelastic damping provided by the layers of tape (viscoelastic materials), thereby proving the importance of using a viscoelastic attenuator as possible amplitudes effect of the bending system. The results were compared to the results of analytical and numerical models in order to obtain experimental validation
Santade, Fransber. "Análise dinâmica do amortecimento em estruturas compostas com material viscoelástico /". Bauru, 2013. http://hdl.handle.net/11449/97030.
Texto completoCoorientador: Paulo José Paupitz Gonçalves
Banca: Laercio Javarez Junior
Banca: Bento Rodrigues de Pontes Junior
Resumo: Neste trabalho foi proposto o estudo do amortecimento estrutural em vigas engastadas com adição de materiais viscoelásticos. As vigas foram montadas na condição engastada-livre e sujeitas de força na extremidade livre. Duas análises foram feitas. O primeiro modelo foi desenvolvido utilizando a Matriz de Impedância de Elemento Espectral (MEE) e o outro modelo foi desenvolvido utilizando Método dos Elementos finitos (MEF). Para validar os modelos numéricos foram realizados ensaios experimentais utilizando um acelerômetro e um martelo de impacto para obter a função de resposta em frequencia para as diferentes configurações de vigas idealizadas. Através dos resultados obtidos pode-se observar e comprovar o comportamento com frequencia de resposta do sistema e detectou-se redução de amplitude devido ao fator incremental de amortecimento viscoelástico proporcionado pelas camadas de fita (materiais viscoelásticos), comprovando assim, a importância da utilização de um material viscoelástico como atenuador de amplitudes no efeito da flexão do sistema. Os resultados experimentais foram comparados aos resultados dos modelos analíticos e numéricos de modo a se obter a validação experimental
Abstract: This work proposes the study of structural damping in beams with added viscoelastic materials. The beams are mounted in a clamped-free condition and subject to force input at the free end. Two types analisis were made. The first model was developed using the Impedance Matrix of Spectral Element. The other model was developed using Finite Element Method (FEM). To validate the numerical models, experimental tests were performed using one accelerometer and a impact hammer to obtain frequency responce function of the diferente beams configurations. From the results we can observe and verify the variation in frequency response of the system and was detected amplitude reduction factor due to the incremental viscoelastic damping provided by the layers of tape (viscoelastic materials), thereby proving the importance of using a viscoelastic attenuator as possible amplitudes effect of the bending system. The results were compared to the results of analytical and numerical models in order to obtain experimental validation
Mestre
Muravyov, Alexander. "Discrete dynamic viscoelastic systems and vibration analysis of an engine supported on viscoelastic mounts". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25124.pdf.
Texto completoBarakos, George. "Viscoelastic simulations in polymer processing". Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6497.
Texto completoRensfelt, Agnes. "Nonparametric identification of viscoelastic materials". Licentiate thesis, Uppsala : Univ. : Dept. of Information Technology, Univ, 2006. http://www.it.uu.se/research/publications/lic/2006-008/2006-008.pdf.
Texto completoStokes, Jason R. "Swirling flow of viscoelastic fluids /". Connect to thesis, 1998. http://eprints.unimelb.edu.au/archive/00000686.
Texto completoSmith, Pierre. "Viscoelastic properties of ionomeric blends". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=73990.
Texto completoMatallah, H. "Numerical simulation of viscoelastic flows". Thesis, Swansea University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638026.
Texto completoBourne, Jeffrey Parnall. "Stress singularities in viscoelastic media". Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47367.
Texto completoSibley, David N. "Viscoelastic flows of PTT fluid". Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518114.
Texto completoAumaitre, Elodie. "Viscoelastic properties of hydrophobin layers". Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607660.
Texto completoReynolds, Matthew. "Active control of viscoelastic metamaterials". Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/377011/.
Texto completoChen, Yuanguo. "Viscoelastic Modeling of Flexible Pavement". University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1258231515.
Texto completoCurry, Richard. "Implementation of viscoelastic Hopkinson bars". Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/10293.
Texto completoThe properties of soft, viscoelastic materials at high strain rates are important in furthering our understanding of their role during blast or impact events. Testing these soft or low impedance materials using metallic bars in a split Hopkinson pressure bar setup, poor signal to noise ratios and impedance mismatching occur. One solution is to use polymeric Hopkinson bars. In this dissertation, Polycarbonate, Polymethyl Methacrylate and Nylon are considered for use as Hopkinson bars. Conventional Hopkinson bar analysis cannot be used on the polymeric bars due to the viscoelastic nature of the bar material. As stress waves propagate along the length of the bars, viscoelastic effects result in dispersion and attenuation. The main topic of this dissertation is to account for this viscoelastic material effect.
Moore, James D. P. "Viscoelastic modelling of crustal deformation". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:6e73f2e2-a8f7-4790-8f13-f562d50302a9.
Texto completoWest, Ray A. "Damping of elastic-viscoelastic beams /". Online version of thesis, 1992. http://hdl.handle.net/1850/11111.
Texto completoAkpan, Edem T. Gogot︠s︡i I︠U︡ G. "Viscoelastic toughening of refractory ceramics /". Philadelphia, Pa. : Drexel University, 2004. http://dspace.library.drexel.edu/handle/1860/284.
Texto completoNiedziela, Dariusz. "On numerical simulations of viscoelastic fluids". [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=981890849.
Texto completoYapici, Kerim. "Numerical Investigation Of The Viscoelastic Fluids". Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609618/index.pdf.
Texto completoZhang, Mengqi. "Linear stability Analysis of Viscoelastic Flows". Thesis, KTH, Mekanik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95137.
Texto completoMiller, Joel C. "Shear flow instabilities in viscoelastic fluids". Thesis, University of Cambridge, 2006. https://www.repository.cam.ac.uk/handle/1810/245318.
Texto completoArvanitaki, A. "Adhesion and traction of viscoelastic contacts". Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/8273.
Texto completoBandey, Helen Luanne. "Viscoelastic characteristics of electroactive polymer films". Thesis, University of Leicester, 1998. http://hdl.handle.net/2381/30016.
Texto completoAggarwal, Nishith. "Computational viscoelastic drop dynamics and rheology". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 122 p, 2008. http://proquest.umi.com/pqdweb?did=1456285651&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Texto completoDemarquette, Nicole Raymonde. "Nonlinear viscoelastic properties of polystyrene solutions". Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60004.
Texto completoThe steady shear stress was found to be independent of shear rate at high shear rates. The Cox-Merz rule was found to be valid for concentrations less than 0.199 g.cm$ sp{-3}$, but a deviation from the rule was observed for higher concentrations. Sigmoidal damping functions, based on both the shear stress measurements and the birefringence measurements, were determined. The exponential stress coefficient and the third normal stress difference were calculated from experimental data for different values of exponential rate constant and different strain scale factor. The exponential rate constant was shown to have a strong influence on both the exponential stress coefficient and the third normal stress difference.
Swarbrick, Sean James. "Finite element simulation of viscoelastic flow". Thesis, Teesside University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278423.
Texto completoKarlsson, Patrik. "Determination of viscoelastic properties of adhesives". Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-35521.
Texto completoNkemzi, D. "Dynamics of elastic/viscoelastic sandwich plates". Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334951.
Texto completoGUTIERREZ, JOSE ANGEL FLORIAN. "VISCOELASTIC FLOW THROUGH MICROCHANNELS WITH CONSTRICTION". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=37214@1.
Texto completoCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Alguns projetos pilotos de injeção de polímeros em campos de produção de petróleo mostraram um incremento na recuperação de óleo, embora os mecanismos que governam a dinâmica do escoamento não são bem compreendidos. Recentes investigações experimentais mostraram que as propriedades viscoelásticas de soluções poliméricas podem alterar o comportamento do escoamento na escala de poros e reduzir a saturação residual de óleo. Para entender esses fenômenos em meios porosos, é importante estudar o escoamento de soluções viscoelásticas através das gargantas dos poros. Este trabalho apresenta um estudo experimental do escoamento de uma solução viscoelástica de PEO (0,1 porcento em peso de óxido de polietileno) de alto peso molecular escoando através de uma constrição, utilizado como modelo de uma geometria de garganta de poro de um meio poroso. Medições de queda de pressão e campos de velocidade do escoamento são obtidos utilizando a técnica de velocimetria por imagem de partículas (Micro-PIV). Experimentos com uma solução viscosa de glicerina (45 porcento em peso de glicerina em água) de viscosidade similar à solução de PEO foram também realizados com a finalidade de estimar os efeitos elásticos da solução de PEO. O escoamento da solução de PEO exibiu uma queda de pressão extra (comportamento não linear) acima de uma condição crítica do escoamento, acima da qual os efeitos elásticos passam a ser preponderantes. Para toda a faixa de vazão explorada, os campos de velocidade da solução de glicerina mostraram um regime de escoamento Newtoniano, enquanto a solução de PEO apresenta instabilidade no escoamento a partir de um número de Weissenberg crítico, coincidindo com o aumento da queda de pressão. Esta instabilidade pode ser relacionada ao aumento da viscosidade extensional na entrada da garganta acima de uma determinada taxa de extensão. Os resultados obtidos indicam a variação do padrão do escoamento da solução polimérica de PEO devido à presença dos efeitos elásticos do polímero, e fornecem informações importantes sobre o comportamento das soluções poliméricas viscoelásticas em um meio poroso e que podem impactar sua utilização na recuperação melhorada de óleo.
Some pilot projects of polymer injection in oil fiel ds have shown an increase in oil recovery, although the mechanisms that govern the flow dynamics are still not well understood. Recent experimental investigations have shown that the viscoelastic properties of polymer solutions may change the pore-scale flow behavior and reduce the residual oil saturation. To understand these phenomena in porous media, it is important to understand viscoelastic flow behavior through the pores-throats. This work presents experimental study of the flow of a high molecular viscoelastic PEO solution (0.1 wt percent Polyethylene Oxide) flowing through a constricted capillary, used as model for a pore-throat geometry of a porous media. Pressure drop measurements are performed and velocity fields are obtained using the micro-particle image velocimetry (Micro-PIV) technique. Experiments with a viscous solution of glycerin (45 wt percent glycerin in water), of similar shear viscosity to the PEO solution were also performed in order to isolate the elastic effects of the PEO solution. The flow of the PEO solution exhibited an extra pressure drop (nonlinear behavior) above a critical flow condition beyond which the elastic forces become relevant. For the entire flow rate range explored, the velocity field of the glycerin solution showed a Newtonian flow regime, while the PEO solution shows instability in the flow above a critical Weissenberg number, coinciding with the onset of the extra pressure drop. This instability in the flow is associated with the high extensional viscosity near the constriction at high enough extension rates. The results show the changes in the flow pattern of the PEO polymer solution due to the presence of the elastic effects of polymer, and provide important information on how viscoelastic polymer solutions behave in a porous media and can impact their use in Enhanced Oil Recovery operations.
Wong, Matthew Q. "Viscoelastic characterization of collagen-GAG scaffolds". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36683.
Texto completoIncludes bibliographical references (p. 43-45).
An experimental study was performed to determine whether or not collagen-GAG scaffolds exhibit linear viscoelastic behavior. Tension tests were performed on dry and hydrated engineered collagen-GAG scaffolds in order to develop a stress-strain curve. Strains that fell in the linear elastic region of these curves were selected and then used in stress relaxation tests that were also performed on dry and hydrated specimens. The relaxation modulus was calculated from the resulting stress relaxation curves at different strain levels and compared to each other to determine viscoelastic linearity. In addition to the determination of viscoelastic linearity, a water bath was designed in the hopes of performing stress relaxation tests in hydrated environment with the temperature maintained at 37°C, the temperature of the human body. These tests will aid in the future studies of how cells contract and apply force to the scaffolds since no previous studies have looked at the time dependent mechanical properties of these scaffolds. Moreover, the data can be used in the future to determine whether the viscoelastic response contributes to cellular processes such as migration speeds, attachment, and contraction.
by Matthew Q. Wong.
S.B.
Byars, Jeffrey Alan. "Experimental characterization of viscoelastic flow instabilities". Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/17413.
Texto completoGerngross, Tobias. "Viscoelastic behaviour in stratospheric balloon structures". Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611506.
Texto completoPuangkird, Bumroong. "Numerical simulations of complex viscoelastic flows". Thesis, Swansea University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683931.
Texto completoWilson, Helen Jane. "Shear flow instabilities in viscoelastic fluids". Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625082.
Texto completoKeshtiban, Ibrahim Jalili. "Numerical simulation of compressible viscoelastic flows". Thesis, Swansea University, 2004. https://cronfa.swan.ac.uk/Record/cronfa43047.
Texto completoSopakayang, Ratchada. "Viscoelastic Models for Ligaments and Tendons". Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77298.
Texto completoPh. D.
Wang, Qi. "Dynamics of viscoelastic slender free jets /". The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487693923196996.
Texto completoYetkinler, Duran Nihat. "Viscoelastic behavior of acrylic bone cements /". The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu148786139602582.
Texto completoRao, Jayathirtha M. "Viscoelastic behavior of electronic packaging materials /". The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487932351058575.
Texto completoRensfelt, Agnes. "Viscoelastic Materials : Identification and Experiment Design". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-111283.
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