Tesis sobre el tema "Visco Elastici"
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Manfroni, Michele. "Controllo del flusso termico in convezione mista tramite fluidi visco-elastici". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/6107/.
Texto completoBertoni, Vanessa. "Analisi probabilistica e uso di controventi dissipativi in telai in accaio e composti acciaio - calcestruzzo". Doctoral thesis, Università degli studi di Trieste, 2011. http://hdl.handle.net/10077/4469.
Texto completoIn questa tesi si indagano vari metodi per la protezione sismica delle strutture a partire da una corretta e realistica valutazione della loro risposta sismica attraverso un approccio probabilistico che tenga conto delle aleatorietà più significative. Se la risposta non soddisfa quanto atteso si può intervenire in vari modi come attraverso l’introduzione di controventi dissipativi. Si analizzano qui due tipologie: i controventi dotati di dispositivi visco elastici e quelli con dispositivi fluido viscosi. Di entrambi si presentano dei metodi di progetto completi con relativi confronti.
XXIII Ciclo
1977
Bella, Maurizio. "Modellazione numerica di strutture sismoresistenti e analisi probabilistiche di tipo montecarlo". Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3460.
Texto completoLo scopo della presente Tesi è lo sviluppo e la messa a punto di una serie di modelli numerici e codici di calcolo atti a modellare il comportamento di strutture sismoresistenti di tipo intelaiato sottoposte ad azione sismica al fine di poter effettuare una valutazione dell'affidabilità strutturale per mezzo di analisi probabilistiche di tipo Montecarlo. In particolare la modellazione dei giunti composti trave-colonna, è stata realizzata definendo un modello meccanico per componenti, atto a descrivere il comportamento del giunto modellato per mezzo di un insieme di elementi rigidi e deformabili, opportunamente connessi tra di loro e a cui sono stati assegnati opportuni modelli istertici. A tale scopo si è proceduto allo sviluppo ed implementazione all’interno del codice di calcolo ABAQUS e ADAPTIC di una serie di modelli isteretici reperiti in letteratura atti alla modellazione numerica delle principali componenti deformative individuabili nei giunti trave colonna e nei dispositivi viscoelastici utilizzati nella realizzazione di controventi dissipativi. Nello sviluppo del modello meccanico per la modellazione del comportamento dei giunti nodi trave colonna composti si è prestata particolare attenzione alla definizione degli elementi che descrivono l’interazione tra la soletta e la colonna. Per agevolare l’esecuzione dell’elevato numero di analisi numeriche richieste dalle analisi probabilistiche di tipo Montecarlo si è inoltre proceduto a sviluppare un pre-processore ed un post-processore in grado di interfacciarsi con i codici di calcolo utilizzati. Nel primo capitolo verrà introdotto il problema della valutazione dell'affidabilità delle strutture. Nel secondo capitolo verranno introdotti i metodi di analisi strutturale con particolare riferimento al metodo dell'analisi probabilistica di tipo montecarlo applicato alla valutazione dell'affidabilità delle strutture. Nel terzo capitolo si esaminerà la problematica della modellazione numerica delle strutture sismoresistenti. Nel quarto capitolo verranno illustrati i modelli numerici sviluppati e implementati nonchè i codici di calcolo sviluppati. Nel quinto capitolo verrà illustrato il processo di validazione dei modelli numerici sviluppati utilizzando i risultati forniti da una serie di indagini sperimentali condotte da vari autori e reperite in letteratura. Infine nel sesto capitolo si procederà alla valutazione dell'affidabilità strutturale di una struttura intelaiata campione. Più precisamente la struttura oggetto dell’indagine è il telaio testato nel European Laboratory for Structural Assessment (ELSA) del Joint Research Center (JRC) di Ispra (Varese). In particolare, per tale struttura verranno determinate le curve di fragilità con riferimento allo spostamento relativo di interpiano (IRDA) assunto come indice di danno strutturale.
XXII Ciclo
1979
Whiting, Andrew Ivan Melville. "Localized buckling of an elastic strut in a visco-elastic medium". Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/37110.
Texto completoSandin, Joakim. "Analysis Methods for Structures with Visco-Elastic Damping Treatment". Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13250.
Texto completoUnder utvecklingen av flygplan undersöks hur vibrationer påverkar flygplansstrukturen under olika förutsättningar. Dessa vibrationer kan skada elektronisk utrustning som är monterad i flygplanskroppen och kan även göra så att materialutmattning uppstår i flygplansstrukturen. För att motverka vibrationer finns det två metoder som är att föredra, antingen att montera vibrationsisolatorer mellan de elektroniska utrustningarna och strukturen eller att ändra designen på strukturer till en styvare. Dessa metoder är enkla att implementera i ett tidigt steg i utvecklingsprocessen men i senare steg, då vibrationsproblem ofta upptäcks, så är det för komplicerat och för dyrt att göra större ändringar på strukturen och så är det ont om plats för att kunna installera vibrations isolatorer. En tredje metod är istället att implementera passiv dämpning i form av dämpningsmattor på ytor av strukturen där kritiska vibrationer uppstår. Effekterna av det strukturella uppförandet när dämpningsmattor är applicerade på en viss struktur har studerats i det här examensarbetet. Syftet är att få en fördjupad kunskap om hur dämpningsmattor kan användas för att reducera vibrationer i flygplan strukturer. Den typ av dämpningsmatta som har studerats är känd som Constrained Layer Damping, CLD, vilken är en sandwich av ett visko-elastiskt lager samt ett styvare lager. Modellerings och simuleringsmetoder som är baserade på kommersiella FE-mjukvaror har utvecklats. Analysmetoderna är baserade på att utföra modalanalys tillsammans med strukturell dämpning. Detta möjliggör att förutse den övergripande dämpningen vid varje strukturell mod. Modellerna för dämpningsmattorna har i det här projektet verifierats med experimental testning av typiska dämpningsmattor. Metodiken kan användas till att prediktera beteendet av dämpade strukturer för att uppnå en effektiv och lättviktig passiv dämpningslösning.
Matar, Ali. "The mechano sorptive creep of softwood in bending". Thesis, London South Bank University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288110.
Texto completoBrunetti, Carlotta. "Frequency-dependent response of snow in uniaxial compression and comparison with numerical simulation". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/7820/.
Texto completoThrower, Edward Neal. "Permanent deformation of flexible road pavements by visco-elastic analysis". Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37877.
Texto completoGarnier, Erell-Isis. "Long waves in water over a visco-elastic muddy seabed". Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67613.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (p. 289-290).
The propagation of surface waves over a flat muddy seabed are studied. Mud is first considered as a Newtonian fluid. Water and mud equations are derived in order to obtain governing equation for surface and interface waves. By the method of multiple scales. nonlinear evolution equations are derived for the harmonic amplitudes. These equations are numerically solved for a finite number of harmonics to show the behavior of surface and interface motions. A drift current in mud is found at the second order., meaning that surface waves induce mud motion. Equation governing the total wave energy variation is derived and used to verify the accuracy of numerical solutions. The model is extended to viscoelastic mud, using the results of four experiments carried on different types of muds. These muds range from very elastic to rather viscous, allowing us to compare hie differences in behavior. Surface and interface variations. mud drift current and energy variations are plotted and compared to the results with Newtonian muds. A sloping muddy seabed is then considered. Mud is modeled as viscoelastic to avoid a constant static current that would happen with Newtonian mud. By the method of multiple scales and by introducing a space-dependent wavenumber, mud drift current and energy variation equations are derived again, taking into account the effect of the slope. An analytic stud v of the surface variations demonstrates that surface and interface waves, as well as drift current, exponentially decay to reach a zero value at the shore.
by Erell-Isis Garnier.
S.M.
Nicely, Clinton R. "Transverse Vibrations of Multi-Walled Nanotubes with Visco-Elastic Layers". University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1227460546.
Texto completoAlrumaih, Wail Saad. "A novel tuned visco-elastic damper for floor vibration abatement". University of Dayton / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1245387294.
Texto completoAl-Rumaih, Wail Saad. "A novel tuned visco-elastic damper for floor vibration abatement". Dayton, Ohio : University of Dayton, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1245387294.
Texto completoSmith, Brennan M. "Functionality of corn and sorghum proteins in visco-elastic dough systems". Diss., Kansas State University, 2012. http://hdl.handle.net/2097/13655.
Texto completoFood Science Institute
Fadi Aramouni
Scott Bean
Zein, the storage protein of corn, has been shown to form a wheat-like dough; however the exact mechanism is unknown since zein lacks the large polymeric proteins found in wheat. To understand how zein forms a dough, different reagents were added during mixing of zein. Salts from the Hofmeister series were used to determine how hydrophobic interactions influence zein’s dough forming ability. In addition, urea, ethanol, and beta mercaptoethanol (β-ME) were also tested to evaluate the effects of protein denaturation and disulfide bonds on zein dough formation and bread quality. Kosmotropic salts had a negative effect on zein dough formation indicating that increasing hydrophobic interactions prevented dough formation. Surface hydrophobicity was found to decrease significantly (p < 0.05) when zein was exposed to 1M or 2M of the kosmotropic salts. Conversely, chaotropic salts had a slight positive effect on zein dough formation as did urea and ethanol. Interestingly, -ME had little effect on zein dough formation demonstrating that disulfide bonds played no role in zein dough development, and that large disulfide linked polymeric protein complexes were not present as found in wheat dough. Specific volumes of zein-starch bread increased as NaCl content in the bread formula decreased. Likewise, including 5% ethanol (v/v) in the bread formula was found to increase bread quality. Experiments were also conducted to compare the functionality of isolated sorghum proteins (kafirins) to commercially available zein produced during wet milling of corn. The effect of steeping, the first step in wet milling, on kafirin functionality was investigated. Sorghum flour was steeped for 0, 72, or 96 hours. Unsteeped sorghum flour was digested with Alcalase for 90 min at 50°C. After steeping or digestion with Alcalase, kafirins were isolated from the remaining material. Both groups of Kafirins had the ability to form a zein-like visco-elastic resin when mixed with warm water by hand. This is the first time that kafirin has been reported to form a visco-elastic resin using only water as a plasticizer.
Ostberg, Martin. "Modelling tools for quieter vehicles : Waves in poro-and visco-elastic continua". Phd thesis, Conservatoire national des arts et metiers - CNAM, 2012. http://tel.archives-ouvertes.fr/tel-00780673.
Texto completoRen, Xiaoan. "The method of arbitrary lines in non-linear visco-elasticity". Thesis, University of Westminster, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240413.
Texto completoMortazavi, Shahriar. "Finite element visco-elastic analysis of permanent deformation in flexible road pavements". Thesis, Imperial College London, 1986. http://hdl.handle.net/10044/1/38112.
Texto completoÖstberg, Martin. "Modelling tools for quieter vehicles : Waves in poro-and visco-elastic continua". Doctoral thesis, KTH, MWL Strukturakustik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95205.
Texto completoQC 20120522
Centre for Eco2 Vehicle Design
Ravish, Masti Sarangapany. "Vibration damping analysis of cylindrical shells partially coated withconstrained visco-elastic layers". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31242169.
Texto completoZheng, Li. "Temperature-dependent visco-elastic-plastic analysis of permanent deformation in bituminous pavements". Thesis, London South Bank University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259911.
Texto completoRahemi, Hossein. "Thermal fracture service life analysis of a case bonded visco-elastic cylinder". Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-172155/.
Texto completoRenault, Amélie. "Caractérisation mécanique dynamique de matériaux poro-visco-élastiques". Thèse, Université de Sherbrooke, 2008. http://savoirs.usherbrooke.ca/handle/11143/1915.
Texto completoPlog, Jan Philip. "Investigation of the visco-elastic behaviour of watersoluble cellulosic derivatives in uniaxial elongation". [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975508008.
Texto completoKang, JiJun. "Determination of elastic-plastic and visco-plastic material properties from instrumented indentation curves". Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13509/.
Texto completoRavish, Masti Sarangapany. "Vibration damping analysis of cylindrical shells partially coated with constrained visco-elastic layers". Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23000867.
Texto completoChurchin, John Anthony. "A Study Of Visco-Elastic Properties Of Denture Liners And Classification Of Terminology". Thesis, Faculty of Dentistry, 1992. http://hdl.handle.net/2123/4205.
Texto completoZiegler, Daniel Alexander [Verfasser] y C. [Akademischer Betreuer] Wieners. "A parallel and adaptive space-time discontinuous Galerkin method for visco-elastic and visco-acoustic waves / Daniel Alexander Ziegler ; Betreuer: C. Wieners". Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/120664690X/34.
Texto completoTsunoda, Katsuhiko. "The role of visco-elasticity on the crack growth behaviour of rubber". Thesis, Queen Mary, University of London, 2001. http://qmro.qmul.ac.uk/xmlui/handle/123456789/28950.
Texto completoJones, Ryan Edward 1974. "Thermally driven visco-elastic measurement technique via spectral variations in scanning probe microscopy cantilevers". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/27098.
Texto completoIncludes bibliographical references (p. 166-167).
Understanding how fluids respond to various deformations is of great importance to a spectrum of disciplines ranging from bio-medical research on joint replacements to sealing technology in industrial machinery. Specifically, this work addresses the need for probing interfacial rheology to understand how lubricants fail as system scales are reduced from bulk dimensions to molecular length scales. In the pursuit of interfacial rheology, one needs a platform capable of the temporal and spatial range and resolution required to quantify the visco-elastic fluid properties in the interfacial regime. With the availability and versatility of AFMs and the mounting models and data related to the performance of SPM probes in a fluid environment, the AFM is an attractive platform to exploit. This thesis will discuss the use of thermal oscillations of an SPM probe to quantify the visco-elastic properties of fluids via spectral variations. There exist theoretical models for the Fluid-Structure Interactions (FSI) of vibrating bodies in incompressible viscous mediums that have been validated. This thesis will discuss how these models have been extended to develop a new visco-elastic FSI model. The analytical results of these models will be quantitatively compared to thermally driven SPM cantilevers to extract fluid properties. The new theory required for modeling the probe dynamics is outlined and the present limitations, for both the analytical and experimental techniques, are discussed.
by Ryan Edward Jones.
Ph.D.
Brown, Susan Jayne 1967. "Gravity, capillary and dilational wave mode resonance at a visco-elastic two-fluid interface". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/28931.
Texto completoIncludes bibliographical references (p. 222-226).
(cont.) space corresponding to experimental conditions to thereby interpret the experimental results. We tested this method on noisy simulated data sets and then applied it to published experimental data sets. We designed an experimental set-up to measure wave number, spatial damping coefficient, and wave slope data for a 3-10 hertz frequency range of transverse and longitudinal waves in a clean enclosed flume. We used kimball-mounted lasers whose beams passed through optical glass in the tank and lid to capture transverse wave motion. The experimental conditions included waves traveling on fatty acid monolayers on aqueous solutions and also waves traveling on a visco-elastic fluid at a variety of temperatures. In addition to the wave data we obtained, we also measured in-situ surface tension. Analyzing the experimental data, we demonstrated the effects of modulation of one wave mode on another. We obtained the rheological parameters for these experimental systems by the inverse method. We used the inverse method to construct the dispersion relation solution space corresponding to the experimental conditions. We used the diagnostic tools for root classification, spatial stability together with a graphical representation of the dispersion relation solution space to understand the physics underlying our experiments. We demonstrated resonance phenomena experimentally with the wave data from the visco-elastic fluid and confirmed this resonance numerically: gravity-capillary resonance near 4.2 hertz ...
This thesis is a study of first order resonance between gravity, capillary and dilational wave modes. Gravity, capillary and dilational waves, occurring at a visco-elastic interface between two fluids, are different modes described by a single linear dispersion relation. Gravity and capillary modes arise due to the restoring forces of surface tension and gravity and result in oscillatory motions transverse to the surface. The dilational, or Marangoni, modes arise due to the elastic nature of the interface and result in longitudinal motion along the interface. The visco-elasticity of the interface may be due to the interfacial nature of the two fluids or it may be due to the presence of a monolayer of surfactant, such as a film on the ocean surface. This visco-elasticity affects the interfacial stress balance and is accounted for in the dispersion relation via interfacial heological parameters. We described resonance as coalescence of the roots of the dispersion relation in complex frequency and wave number space. We used this description to explain numerical and experimental resonance phenomena noted in previous studies. We classified some of the roots of the dispersion relation as primarily gravity, capillary or dilational modes. We numerically determined the dependence on interfacial rheology of root coalescence (resonance) and the boundaries of spatial stability of the modes. We used these diagnostic tools to characterize the conditions for both gravity-capillary and capillary-dilational modal resonances. We developed an inverse method from which interfacial rheological parameters can be determined from experimental measurements of wave number, frequency and spatial damping coefficient. We used this tool to construct the dispersion relation solution
by Susan Jayne Brown.
Sc.D.
Östberg, Martin. "Modelling Tools for Quieter Vehicles : Effective Vibro-Acoustical Modelling of Rotationally Symmetric Structures Consisting of Visco-Elastic and Poro-Elastic Media". Licentiate thesis, KTH, VinnExcellence Center for ECO2 Vehicle design, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-13251.
Texto completoBragaglia, Massimiliano <1973>. "Studio del comportamento visco-elastico del conglomerato bituminoso con il metodo degli elementi distinti particellari". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/93/1/Tesi_dottorato.pdf.
Texto completoBragaglia, Massimiliano <1973>. "Studio del comportamento visco-elastico del conglomerato bituminoso con il metodo degli elementi distinti particellari". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/93/.
Texto completoBlignaut, Caitlyn. "A Non-linear Visco-elastic Model for Dynamic Finite Element Simulation of Bovine Cortical Bone". Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/33433.
Texto completoVerma, Navin Prakash. "Viscous Dampers for Optimal Reduction in Seismic Response". Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/43716.
Texto completoMaster of Science
Ames, Nicoli M. (Nicoli Margret) 1978. "An internal variable theory for isotropic visco-elastic-plastic solids : application to indentation of amorphous polymeric solids". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/33162.
Texto completoThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaves 91-92).
A significant advance in modeling the plastic deformation of amorphous polymers has been made by Parks, Argon, Boyce, Arruda, and their co-workers (e.g. Parks, Argon, & Bagepalli, 1985; Boyce, Parks, & Argon, 1998; Arruda & Boyce, 1993), and by Wu and Van der Giessen (1993). Although these models phenomenologically capture the large deformation elastic-viscoplastic response of these materials in a reasonably accurate manner, they do not adequately account for the creep response of these materials at stress levels below those causing "macro-yield", as well as the Bauschinger-type reverse yielding phenomena at strain levels less than ~ 30% associated with the macro-yield transient. Anand (2003) has recently generalized the model of Anand and Gurtin (2003) to begin to capture these important aspects of these material's mechanical response. In this work, we summarize Anand's three-dimensional theory and then specialize the constitutive equations to an approximate one-dimensional form. Also, we describe our monotonic, cyclic and creep experiments on the amorphous polymeric solid poly(methyl methacrylate) (PMMA), at ambient temperature and stress states under which this material does not exhibit crazing, and we outline detailed procedures for material parameter determination from these experiments. We have implemented the three-dimensional constitutive equations in the finite-element computer program ABAQUS/Explicit (ABAQUS, Inc., 2002), and using this finite-element program, we show numerical results to some representative problems in microindentation, and compare them against corresponding results from physical experiments.
by Nicoli Margret Ames.
S.M.
Janovjak, Harald. "Exploring the Mechanical Stability and Visco-elasticity of Membrane Proteins by Single-Molecule Force Measurements". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1135090167025-44737.
Texto completoNguyen, Dang Dan. "Revêtements polymères sous contraintes environnementales couplées". Phd thesis, Université de La Rochelle, 2012. http://tel.archives-ouvertes.fr/tel-01065519.
Texto completoGrasso, Eva. "Modelling visco-elastic seismic wave propagation : a fast-multipole boundary element method and its coupling with finite elements". Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00730752.
Texto completoBarros, Renato Marques de. "Funções de Green e de influencia para meios visco-elasticos transversalmente isotropicos no dominio da frequencia". [s.n.], 2001. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264035.
Texto completoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-07-31T20:40:49Z (GMT). No. of bitstreams: 1 Barros_RenatoMarquesde_D.pdf: 12889106 bytes, checksum: ae50d7f1404dacf5b43d8e4007ad231d (MD5) Previous issue date: 2001
Resumo: O objetivo do presente trabalho é a síntese de Funções de Green e de Influência no domínio da freqüência para meios transversalmente isotrópicos visco-elásticos. Inicialmente são analisados problemas bidimensionais. A transformada integral de Fourier é aplicada no procedimento de solução, com inversão numérica. Soluções fundamentais para o espaço completo, semi-espaço e meios estratificados horizontalmente são consideradas. Na seqüência são considerados problemas tridimensionais em coordenadas retangulares e cilíndricas nos quais a transformada integral de Hankel com inversão numérica foi empregada. As soluções obtidas foram comparadas com as soluções disponíveis na literatura. Um conjunto de soluções axi-simétricas para o espaço completo, semi-espaço e meio multi-estratificado foi, também, sintetizado. O método da matriz de rigidez dinâmica foi, então, empregado para problemas axi-simétricos e bidimensionais. As soluções encontradas foram validadas com numerosos resultados disponíveis na literatura. As funções de Green e de Influência sintetizadas podem ser incorporadas tanto nas versões direta como indireta do Método dos Elementos de Contorno para a análise do comportamento dinâmico estacionário de meios transversalmente isotrópicos e visco-elásticos
Abstract: The present work synthesizes frequency domain Green and Influence Functions for transversely isotropic visco-elastic continua. Initially the two-dimensional case is treated. The Fourier integral transform is applied in the solution procedure, with numerical inversion. Fundamental solutions for full-space, half-space and horizontally layered media are considered. The stiffness matrix approach is used to obtain solutions for multi-layered media. In the sequence the three-dimensional case is considered. A series of axisymmetric solutions for for full-space, half-space and horizontally layered media are also synthesized. The matrix stiffness approach is also applied to the axisymmetric problem. The Hankel integral transform with numerica1 inversion is applied to the 3D cases. Numerical solutions are validated by comparisons whenever results are available in the literatura. The synthesized Green and Inf1uence Functions may be incorporated in the Direct or Indirect Versions of the Boundary Element Method to analyse the stationary dymanic behavior of transversely isotropic vico-elastic media
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutor em Engenharia Mecânica
Thomazo, Luiz Henrique. "Formulação do metodo dos elementos de contorno indireto para resposta transiente em meios visco-elasticos 2D". [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263977.
Texto completoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Este trabalho apresenta uma metodologia para a realização de análises dinâmicas estacionárias e transientes em domínios visco-elásticos limitados ou ilimitados, utilizando-se o Método dos Elementos de Contorno. São utilizados como estados auxiliares soluções não-singulares de problemas do semi-espaço e do espaço completo de meios visco-elásticos. Os estados visco-elásticos auxiliares são sintetizados numericamente, tanto no domínio da freqüência, como no domínio do tempo. Os mencionados estados auxiliares são constituídos das soluções em tensão e deslocamento resultantes de cargas espacialmente constantes, aplicadas sob segmentos lineares tanto na superfície de semi-espaços, como no interior de espaços completos. Inicialmente os estados auxiliares são sintetizados numericamente no domínio da freqüência, dando origem à análise de problemas estacionários. Na seqüência estados auxiliares transientes são obtidos a partir da aplicação da transformada de Fourier rápida (FFT) sobre os estados estacionários mencionados. Os estados auxiliares são utilizados para a síntese de uma versão não singular Indireta do MEC (MEC-I) tanto no domínio da freqüência quanto no domínio do tempo. No trabalho ainda é formulada e implementada a inclusão de um corpo rígido interagindo com o meio discretizado pelo MEC-I. O comportamento visco-elástico do contínuo é introduzido pelo princípio da correspondência e são analisados os modelos de histerése constante e de Kelvin-Voigt
Abstract: The main purpose of the present work is to further develop a methodology to perform stationary and transient dynamic analysis of viscoelastic continua by the Boundary Element Method. Numerically synthetized stationary and transient, half-space and full-space auxiliary states are employed to render a non-singular implementation of the indirect version of the Boundary Element Method, IBEM. The auxiliary states used in this word are displacement and traction components stemming from the solution two stress bounary value problems. A constant traction distribution applied at a linear segment over the viscoelastic half-space surface and at the interior of the viscoelastic full-space describe the solutions applied to formulate the BEM. The IBEM is formulated and implemented to render the dynamic solution of bounded and unbounded domains. The interaction of the IBEM mesh with a massless rigid body is also formulated in the context of this work. Viscoelastic effects are included by means of the correspondence principle. The influence of the constant hysteresis and the Kelvin-Voigt damping models are studied.
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
Schuchardt, Arnim [Verfasser]. "On the Mechanical Modeling, Visco-Elasticity and Application of Aerographite, a 3D Carbon Nano-Material / Arnim Schuchardt". Kiel : Universitätsbibliothek Kiel, 2016. http://d-nb.info/1081366788/34.
Texto completoTaira, Claudio. "Avaliação do desempenho em laboratório de misturas asfálticas densas utilizando asfalto convencional (CAP-20) e asfalto modificado com polímero SBS (BETUFLEX B 65/60)". Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18137/tde-09052016-111805/.
Texto completoThe purpose of this study is to evaluate the performance of asphalt mixes using conventional binder and the same binder modified with SBS polymer (Betuflex B 65/60) based on Marshall test, static and dynamic creep tests, indirect tensile strength test and resilient modulus by indirect tensile test, with the same granulometric composition and different binders contents. In Marshall test, polymer modified asphalt mixes presented better stability performance than conventional asphalt mixes in most of binders contents, despite of the higher flow values obtained for all binders contents. The static creep test results indicated that this test does not clearly distinguish the effect of polymer in asphalt mixes while the results of dynamic creep test indicated the opposite, i. e., polymer modified asphalt mixes deformations are smaller for most of the asphalt binders contents studied. The indirect tensile strength test results showed a better performance of modified asphalt. The results of resilient modulus by indirect tensile test at 25°C showed smaller values for modified asphalt, while the results at 5ºC and 40ºC did not show differences between the asphalt mixes. The mathematics modelling of the creep and recovering curves according to constitutive equations of some basic visco- elastic models showed a difference between the values of some constitutive elements in both cases, dynamic and static tests.
Hamitou, Okba. "Efficient preconditioning method for the CARP-CG iterative solver for the solution of the frequency-domain visco-elastic wave equation". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAM087/document.
Texto completoA robust and efficient wave modeling method is the cornerstone of high resolution seismic inversion methods such as the frequency-domain Full Waveform Inversion (Virieux, 2009). After discretization, frequency-domain wave modeling amounts to the solution of large (up to several billion of unknowns for realistic case studies), sparse, indefinite and ill-conditioned linear systems. Furthermore, seismic inversion methods require the solution of this problem for numerous sources (from several thousands up to tens of thousands). In the acoustic approximation, 3D real case studies can be handled efficiently using direct solvers. However because of their tremendous intrinsic memory requirements, they are not yet adapted to the solution of the 3D elastodynamics equations. Iterative solvers provide an alternative to direct solvers. However, they require a preconditioning strategy to ensure convergence for the frequency-domain wave equation. Besides, multiple right-hand sides linear systems are not treated as efficiently as direct solvers do.In this thesis, we are interested in the use of a robust iterative solver adapted to the solution of these systems called CARP-CG (Gordon, 2010). The CARP-CG method has shown robust convergence properties for 2D and 3D elastic problems in highly heterogeneous media compared to standard Krylov methods such as GMRES or Bi-CGSTAB which require the use of a preconditioner to ensure convergence (Li, 2015). Despite the good convergence properties of CARP-CG, the latter still requires a large number of iterations to reach sufficient accuracy. I introduce an efficient preconditioning strategy adapted to the CARP-CG method and the frequency-domain wave problem. This preconditioner is computed as a sparse approximate inverse of a strongly damped wave propagation operator. The computation of the preconditioner is performed in a massively parallel algorithm for distributed memory architectures.The efficiency of the preconditioner is evaluated on several case studies. First, applications are performed on realistic synthetic models in the 2D visco-acoustic approximation (up to $40$ Hz) and the 2D visco-elastic approximation (up to $20$ Hz). These studies show that the CARP-CG method together with the preconditioning strategy is robust and efficient. The number of iterations is significantly reduced (up to a factor $9$) enabling a speedup in the computation time by a factor up to $3.5$. Second, this method is investigated in the 3D elastic approximation on a realistic synthetic case study on the range of frequencies 1.25 to 7.5 Hz. Very encouraging results are obtained with a significant reduction in the number of iterations. A slow increase of the number of iterations with respect to the frequency is noted.This preconditioning strategy adapted to the CARP-CG method implies larger memory requirements. However, this extra memory cost remains one order lower compared to direct solver memory requirement, and should be affordable on standard HPC facilities. The main bottleneck preventing from the possible use of this iterative solver for 3D elastic FWI remains the computation time for the wave equation solves
Akogyeram, Samuel. "Bonding and debonding mechanism of pressure sensitive adhesives". Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/12765.
Texto completoDamarla, Gowrisankar. "Determination of Wear in Polymers Using Multiple Scratch Test". Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4627/.
Texto completoHadj, Mohammed el. "Applications des methodes multi-grilles aux calculs des structures elastique et visco-plastique". Paris, ENMP, 1987. http://www.theses.fr/1987ENMP0047.
Texto completoWood, Brian Henry. "Experimental validation of an integrated FRP and visco-elastic hardening, damping, and wave-modulating system for blast resistance enhancement of RC columns". Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Wood_09007dcc80538e4c.pdf.
Texto completoVita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed August 28, 2008) Includes bibliographical references (p. 112-115).
Gelineau, Pierre. "Caractérisation morphologique et homogénéisation élastique et visco-élastique de polymères renforcés de nano-plaquettes d'argile". Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2193/document.
Texto completoThis work aims to understand the influence of nano-clay platelets on the mechanical behavior of nano–reinforced polymers. This understanding requires a good description of the micro-structure and a characterization of the mechanical behavior of these materials (elastic and visco-elastic). At the micro-scale, the size of the aggregates of nano-platelets and their spatial distribution were observed using TEM. At the nano-scale, the d-spacing between platelets within an aggregate was measured using XRD. These experimental techniques highlighted intercalated micro-structures. At the macroscale, monotonic tensile tests and Dynamic Mechanical Analysis (DMA) have been performed to study the mechanical behavior of the materials. To predict the macroscopic elastic behavior, the combination of two approaches has been considered; hybrid and matrix-inclusion models. This needed tool allows to anticipate the behavior of these materials without process them. By the consideration of the morphology into the modeling scheme, the influence of the micro-structure on the macroscopic behavior can be studied. The considered multiscale approach is able to estimate the macroscopic behavior of an intercalated nano-composite, in which a polymeric matrix is reinforced by stacks of bi-layers sandwiches (nano-clay platelets and polymer). It was observed from their comparison that the modeling predictions well bounded the experimental data in elasticity. This multi-scale approach was extended in the context of viscoelasticity and the predictions in this context were in good agreement with the experimental data for the complex modulus and for the storage and loss moduli
Ramalho, Denise Alves. "Estudo da influência dos perfis de solo na resposta dinâmica de sistemas rotor-fundação". [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264189.
Texto completoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: O objetivo deste trabalho é estender e melhorar a análise dinâmica de um sistema rotorfundação-solo através da inclusão de modelos distintos de perfis de solo. Obtém-se a resposta desbalanceada de um rotor Laval (Jeffcott) simples bidimensional com mancais rígidos. O rotor é colocado sobre uma fundação de bloco rígido. Os perfis de solo incluem o modelo clássico de semi-espaço e o modelo de solo sobre base rígida. Em particular, uma camada sobre base rígida com diferentes valores de profundidade será considerada. A resposta dinâmica do solo é obtida no domínio da freqüência. O mecanismo de amortecimento interno do solo é considerado. Vários estudos paramétricos são realizados para avaliar o papel da espessura da camada do solo, do coeficiente de amortecimento do solo, da inércia da fundação e da altura dos mancais na resposta ao desbalancemento do rotor. Acredita-se que a análise deste modelo simples de rotor-fundação-solo ajudará a esclarecer o papel dos parâmetros mencionados na resposta dinâmica do rotor
Abstract: The aim of the present work is to extend and improve the dynamic analysis of a rotorfoundation-soil system by including the modelling of distinct soil profiles. The unbalance response of a simple two-dimensional Laval (Jeffcott) rotor with rigid bearings is performed. The rotor is attached to a rigid strip foundation (block foundation). The soil profiles, on the other hand, include the classical half-space but also stratified soils. In particular, a layer with various depths over a bedrock will be considered. The soil¿s dynamic response is furnished in terms of frequency dependent complex impedances. The soil internal damping mechanism is also addressed by making the soil a viscoelastic continuum. A series of parametric studies are perfomed to assess the role of soil layer thickness, soil internal damping coefficient, foundation inertia and bearing height on the rotor unbalance response. It is believed that the analysis of this simple otor-foundation-soil model will help to clarify the role of the mentioned parameters on the rotor dynamic response
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
Li, Ying. "Digital Mix Design for Performance Optimization of Asphalt Mixture". Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/72959.
Texto completoPh. D.