Tesis sobre el tema "Hysteresis modelling"
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Lahey, Timothy. "Modelling Hysteresis in the Bending of Fabrics". Thesis, University of Waterloo, 2002. http://hdl.handle.net/10012/941.
Texto completoWu, Zhengqiu. "Nonlinear modelling of three phase multi limb transformers". Thesis, London South Bank University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245156.
Texto completoScheffler, Gregor. "Validation of hygrothermal material modelling under consideration of the hysteresis of moisture storage". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1207758173790-40696.
Texto completoDie Genauigkeit hygrothermischer Bauteilsimulation hängt maßgeblich von den verwendeten Materialfunktionen ab. Sie werden durch die Materialmodellierung bestimmt, welche die Verbindung zwischen den aus Basisexperimenten gewonnenen Speicher- und Transportparametern sowie den innerhalb der Bilanz- und Flussgleichungen definierten Speicher- und Transportkoeffizienten herstellt. Ziel der vorliegenden Arbeit ist zum einen die Entwicklung eines flexiblen, breit anwendbaren und gleichzeitig nicht auf den gegenwärtigen Stand der Transporttheorie beschränkten Materialmodells. Dessen Grenzen und Möglichkeiten sollen zum anderen auf der Grundlage spezieller instationärer Feuchteprofilmessungen anhand von vier Baustoffen untersucht und aufgezeigt werden. Ausgangspunkt der Arbeit ist eine ausführliche Beleuchtung sowohl der vorhandenen Modellansätze als auch der zur Verfügung stehenden experimentellen Methoden zur Bestimmung hygrothermischer Basisparameter. Auf dieser Grundlage wird die Materialmodellierung in den Kontext der aus der Thermodynamik abgeleiteten Wärmeund Feuchtetransporttheorie eingeordnet. Die damit verbundenen Grenzen und Einschränkungen werden hervorgehoben und Entwicklungsmöglichkeiten sowie weiterer Entwicklungsbedarf aufgezeigt. Dieser umfasst drei Bereiche: die Experimente zur Bestimmung von Basisparametern, die Materialmodellierung, sowie Experimente zur Modellvalidierung. Die Reihe der Basisexperimente wird um den Trocknungsversuch unter definierten Bedingungen erweitert. Die verschiedenen Einflüsse auf die Trocknung und deren Anwendung in der Kalibrierung hygrothermischer Materialmodellierung werden herausgestellt und bewertet. Darauf aufbauend wird eine Apparatur entworfen, gebaut und angewendet. Schließlich werden Kriterien zur Standardisierung und Ableitung eines Einzahlenkennwertes evaluiert. Sinnvolle Erweiterungen werden aufgezeigt. Es wird ein eigenes Materialmodell auf der Grundlage eines Porenbündelansatzes hergeleitet, welches mit einem mechanistischen Ansatz gekoppelt wird, der den Feuchtetransport in seriell und parallel strukturierte Bereiche untergliedert. Die abgeleitete Flüssigwasserleitfähigkeit wird anhand von Leitfähigkeitsmessdaten im nahe gesättigten sowie im hygroskopischen Feuchtebereich justiert. Zwei interne Modellparameter werden anschließend unter Berücksichtigung der Hysterese der Feuchtespeicherung anhand des Aufsaug- und des Trocknungsversuches kalibriert. Das Materialmodell ist zur Erleichterung der Anwendung in ein Computerprogramm zur Anpassung an die Labordaten implementiert worden. Das Programm wird auf die vier Baustoffe Ziegel, Kalksandstein, Porenbeton und Calciumsilikat angewendet. Die entsprechend angepassten Materialfunktionen werden gezeigt und diskutiert. Im Rahmen der Kalibrierung wird eine hervorragende Übereinstimmung zwischen gemessenem und berechnetem Materialverhalten erreicht. Zur Modellvalidierung wird die Augenblicksprofilmethode (IPM) für die bauphysikalische Anwendung erweitert. Spezielle Apparaturen werden entwickelt und Versuchsabläufe entworfen. Modelle zur Ableitung des Wassergehaltes aus mit Hilfe der Time Domain Reflectometry (TDR) gewonnenen Dielektrizitätsmessdaten werden evaluiert und implementiert. Schließlich wird ein umfangreiches Programm an Feuchteprofilmessungen im hygroskopischen und überhygroskopischen Feuchtebereich umgesetzt und ausgewertet. Im Rahmen der Validierung werden die Entwicklungen auf experimenteller sowie auf Modellierungsebene zusammengeführt. Die IPM Experimente werden anhand der gemessenen Anfangs- und Randbedingungen und auf der Grundlage der angepassten und kalibrierten Materialfunktionen nachgerechnet. Der Vergleich zwischen Messung und Rechnung offenbart die Stärke der entwickelten Materialmodellierung ebenso, wie den Einfluss der auf Ebene der Transporttheorie getroffenen Vereinfachungen. Ein deutlicher Einfluss der sich aus der Prozessgeschichte sowie der Prozessdynamik zusammensetzenden Hysterese der Feuchtespeicherung kann nachgewiesen werden. Mit der vorliegenden Arbeit ist somit nicht nur die Materialmodellierung entscheidend weiterentwickelt, die Reihe der einfachen Basisexperimente um einen wesentlichen Versuch erweitert und die Augenblicksprofilmethode für bauphysikalische Belange anwendbar gemacht worden, es wurden auch die Einflüsse der Prozessgeschichte, und erstmals auch der Prozessdynamik, auf den Feuchtetransport sowie die sich einstellenden Feuchteprofile deutlich aufgezeigt und nachgewiesen. Es ist demnach nicht nur ein Materialmodell, welches den gestellten Anforderungen an Flexibilität, breite Anwendbarkeit und Erweiterbarkeit genügt, entwickelt worden, es wird mit den gewonnenen Messdaten auch die Grundlage weiterer Forschung zur Verfügung gestellt
Scheffler, Gregor. "Validation of hygrothermal material modelling under consideration of the hysteresis of moisture storage". Doctoral thesis, Technische Universität Dresden, 2007. https://tud.qucosa.de/id/qucosa%3A23813.
Texto completoDie Genauigkeit hygrothermischer Bauteilsimulation hängt maßgeblich von den verwendeten Materialfunktionen ab. Sie werden durch die Materialmodellierung bestimmt, welche die Verbindung zwischen den aus Basisexperimenten gewonnenen Speicher- und Transportparametern sowie den innerhalb der Bilanz- und Flussgleichungen definierten Speicher- und Transportkoeffizienten herstellt. Ziel der vorliegenden Arbeit ist zum einen die Entwicklung eines flexiblen, breit anwendbaren und gleichzeitig nicht auf den gegenwärtigen Stand der Transporttheorie beschränkten Materialmodells. Dessen Grenzen und Möglichkeiten sollen zum anderen auf der Grundlage spezieller instationärer Feuchteprofilmessungen anhand von vier Baustoffen untersucht und aufgezeigt werden. Ausgangspunkt der Arbeit ist eine ausführliche Beleuchtung sowohl der vorhandenen Modellansätze als auch der zur Verfügung stehenden experimentellen Methoden zur Bestimmung hygrothermischer Basisparameter. Auf dieser Grundlage wird die Materialmodellierung in den Kontext der aus der Thermodynamik abgeleiteten Wärmeund Feuchtetransporttheorie eingeordnet. Die damit verbundenen Grenzen und Einschränkungen werden hervorgehoben und Entwicklungsmöglichkeiten sowie weiterer Entwicklungsbedarf aufgezeigt. Dieser umfasst drei Bereiche: die Experimente zur Bestimmung von Basisparametern, die Materialmodellierung, sowie Experimente zur Modellvalidierung. Die Reihe der Basisexperimente wird um den Trocknungsversuch unter definierten Bedingungen erweitert. Die verschiedenen Einflüsse auf die Trocknung und deren Anwendung in der Kalibrierung hygrothermischer Materialmodellierung werden herausgestellt und bewertet. Darauf aufbauend wird eine Apparatur entworfen, gebaut und angewendet. Schließlich werden Kriterien zur Standardisierung und Ableitung eines Einzahlenkennwertes evaluiert. Sinnvolle Erweiterungen werden aufgezeigt. Es wird ein eigenes Materialmodell auf der Grundlage eines Porenbündelansatzes hergeleitet, welches mit einem mechanistischen Ansatz gekoppelt wird, der den Feuchtetransport in seriell und parallel strukturierte Bereiche untergliedert. Die abgeleitete Flüssigwasserleitfähigkeit wird anhand von Leitfähigkeitsmessdaten im nahe gesättigten sowie im hygroskopischen Feuchtebereich justiert. Zwei interne Modellparameter werden anschließend unter Berücksichtigung der Hysterese der Feuchtespeicherung anhand des Aufsaug- und des Trocknungsversuches kalibriert. Das Materialmodell ist zur Erleichterung der Anwendung in ein Computerprogramm zur Anpassung an die Labordaten implementiert worden. Das Programm wird auf die vier Baustoffe Ziegel, Kalksandstein, Porenbeton und Calciumsilikat angewendet. Die entsprechend angepassten Materialfunktionen werden gezeigt und diskutiert. Im Rahmen der Kalibrierung wird eine hervorragende Übereinstimmung zwischen gemessenem und berechnetem Materialverhalten erreicht. Zur Modellvalidierung wird die Augenblicksprofilmethode (IPM) für die bauphysikalische Anwendung erweitert. Spezielle Apparaturen werden entwickelt und Versuchsabläufe entworfen. Modelle zur Ableitung des Wassergehaltes aus mit Hilfe der Time Domain Reflectometry (TDR) gewonnenen Dielektrizitätsmessdaten werden evaluiert und implementiert. Schließlich wird ein umfangreiches Programm an Feuchteprofilmessungen im hygroskopischen und überhygroskopischen Feuchtebereich umgesetzt und ausgewertet. Im Rahmen der Validierung werden die Entwicklungen auf experimenteller sowie auf Modellierungsebene zusammengeführt. Die IPM Experimente werden anhand der gemessenen Anfangs- und Randbedingungen und auf der Grundlage der angepassten und kalibrierten Materialfunktionen nachgerechnet. Der Vergleich zwischen Messung und Rechnung offenbart die Stärke der entwickelten Materialmodellierung ebenso, wie den Einfluss der auf Ebene der Transporttheorie getroffenen Vereinfachungen. Ein deutlicher Einfluss der sich aus der Prozessgeschichte sowie der Prozessdynamik zusammensetzenden Hysterese der Feuchtespeicherung kann nachgewiesen werden. Mit der vorliegenden Arbeit ist somit nicht nur die Materialmodellierung entscheidend weiterentwickelt, die Reihe der einfachen Basisexperimente um einen wesentlichen Versuch erweitert und die Augenblicksprofilmethode für bauphysikalische Belange anwendbar gemacht worden, es wurden auch die Einflüsse der Prozessgeschichte, und erstmals auch der Prozessdynamik, auf den Feuchtetransport sowie die sich einstellenden Feuchteprofile deutlich aufgezeigt und nachgewiesen. Es ist demnach nicht nur ein Materialmodell, welches den gestellten Anforderungen an Flexibilität, breite Anwendbarkeit und Erweiterbarkeit genügt, entwickelt worden, es wird mit den gewonnenen Messdaten auch die Grundlage weiterer Forschung zur Verfügung gestellt.
Hatipogullari, Metin. "Modelling of contact lines on heterogeneous substrates :stick-slip and contact angle hysteresis". Doctoral thesis, Universite Libre de Bruxelles, 2020. https://dipot.ulb.ac.be/dspace/bitstream/2013/304847/5/contratMH.pdf.
Texto completoDoctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
Zhang, Zhidong. "Modelling of sorption hysteresis and its effect on moisture transport within cementitious materials". Thesis, Paris Est, 2014. http://www.theses.fr/2014PEST1055/document.
Texto completoThe durability of reinforced concrete structures and their service life are closely related to the simultaneous occurrence of many physical and chemical phenomena. These phenomena are diverse in nature, but in common they are dependent on the moisture properties of the material. Therefore, the prediction of the potential degradation of cementitious materials requires the study of the movement of liquid-water and gas-phase transport in the material which is considered as a porous medium. In natural environment, structures are always affected by periodic variations of external relative humidity (RH). However, most moisture transport models in the literature only focus on the drying process. There are few researches considering both drying and wetting, although these conditions represent natural RH variations. Even few studies take into account hysteresis in moisture transport. Thus, this work is devoted to better understand how the moisture behaviour within cementitious materials responds to the ambient RH changes through both experimental investigations and numerical modelling. In particular, hysteretic effects will be included in numerical modelling. In this thesis, we first recalled a complicate multi-phase continuum model. By theoretical analysis and experimental verification, a simplified model can be obtained for the case of that the intrinsic permeability to liquid-water is smaller than the intrinsic permeability to gas-phase. The review of commonly-used hysteresis models enabled to conclude a set of best models for the prediction of water vapour sorption isotherms and their hysteresis. After that, the simplified model was coupled with selected hysteresis models to simulate moisture transport under drying and wetting cycles. Compared with experimental data, numerical simulations revealed that modelling with hysteretic effects can provide much better results than non-hysteresis modelling. Among different hysteresis models, results showed that the use of the conceptual hysteresis model, which presents closed form scanning loops, can provide more accuracy predictions. Further simulations for different scenarios were also performed. All comparisons and investigations enhanced the necessity of considering hysteresis to model moisture transport for varying relative humidity at the boundary. The investigation of moisture penetration depth could provide a better understanding of how deep moisture as well as ions can move into the material. Furthermore, the analysis revealed that the consideration of Knudsen effects for diffusion of vapour can improve the prediction of the apparent diffusivity
Mousavi, Seyed Ali. "Electromagnetic Modelling of Power Transformers with DC Magnetization". Licentiate thesis, KTH, Elektroteknisk teori och konstruktion, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-105395.
Texto completoQC 20121121
Ribbenfjärd, David. "Electromagnetic transformer modelling including the ferromagnetic core". Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-13080.
Texto completoQC20100708
Chen, Rui. "Experimental study and constitutive modelling of stress-dependent coupled hydraulic hysteresis and mechanical behaviour of an unsaturated soil /". View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20CHEN.
Texto completoBenamer, Mohamed R. Omar. "Computational modelling of hysteresis and damage in reinforced concrete bridge columns subject to seismic loading". Thesis, Swansea University, 2013. https://cronfa.swan.ac.uk/Record/cronfa42309.
Texto completoPongdhorn, Sae-Oui. "Measurement and modelling of the influence of hysteresis on the internal temperature rise of rubber components". Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/27205.
Texto completoMaritz, Johannes Christoffel. "Numerical modelling and experimental measurement of the temperature distribution in a rolling tire". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97115.
Texto completoENGLISH ABSTRACT: Rubber is the main component of the pneumatic tire. When rubber is put under cyclic loading, like when a tire is rolled, heat is generated and stored in the rubber, due to hysteresis. Heat stored in the tire is increased by factors like under-inflation, overloading, speeding and defects in the tire. The heat causes high temperatures in the tire due to the poor thermal conductivity of rubber. When the temperature in the rubber increases to 185 °C, pyrolysis and thermo-oxidation starts and can cause the tire to eventually explode. A numerical model of a rolling passenger vehicle tire was developed to calculate the temperature distribution inside the tire and analyse the effect of different operating conditions on the temperature. Operating conditions include loading, inflation pressure, rolling velocity and ambient temperature. The tire was modelled by a single rubber type, using the Mooney-Rivlin material model. The bead wire was modelled using an isotropic material model, while the body and steel cord plies were modelled as rebars. The cavity, used to inflate the tire, included the pressure increase due to the volume change, when the tire is loaded. The numerical model was validated using experimental data from tests done on an actual tire. These tests included deformation and contact stress analysis, as well as surface temperature measurements. Numerical results showed an increase in temperature when the load, rolling velocity and the ambient temperature were increased, as well as when the inflation pressure was decreased. The trends of the numerical data matched the trends of the experimental data. However, the values of the numerical model were not consistent with the experimental data due to material properties from literature being used to model the tire.
AFRIKAANSE OPSOMMING: Rubber is die hoofkomponent in die pneumatiese band. As rubber onder ’n sikliese las geplaas word, soos wanneer ’n band rol, word hitte gegenereer en in die rubber gestoor as gevolg van histerese. Die hitte wat in die band gestoor word, word verhoog deur faktore soos lae inflasiedruk, hoë las, hoë rol snelhede en gebreke in die band. Die hitte veroorsaak hoë temperature in die band weens die swak termiese geleiding van rubber. As die temperatuur in die band hoër as 185 °C raak, vind piroliese en termo-oksidasie plaas en die band kan uiteindelik ontplof. ’n Numeriese model van ’n passasiersmotorband is ontwikkel om die temperatuurverspreiding te bepaal, asook om die effek van verskillende werkstoestande op die temperatuur te analiseer. Die band is gemodelleer met een tipe rubber en die Mooney-Rivlin materiaal-model is gebruik om die rubber te beskryf. Die spanrand van die band is deur ’n isotropiese materiaalmodel gemodelleer, terwyl die hoof- en staalkoordlae as bewapening gemodelleer is. Die holte wat gebruik word om die band op te blaas, neem die druk toename as gevolg van die verandering in volume in ag wanneer die band belas word. Die numeriese model was bekragtig met eksperimentele data wat deur toetse op ’n werklike band onttrek is. Die toetse sluit die volgende in: vervormingen kontakspanninganalises, asook temperature wat op die oppervlak van die band gemeet is. Die numeriese resultate toon ’n toename in temperatuur wanneer die las, rolsnelheid en omgewingstemperatuur verhoog word, asook waneer die inflasiedruk verlaag word. Die numeriese model se tendense stem ooreen met die eksperimentele data, maar die waardes van die numeriese model is nie in ooreenstemmig met die eksperimentele data nie. Die verskil is as gevolg van die materiaaleienskappe wat uit die literatuur geneem is.
Mellia, Federico. "Modelling and control of an hydraulic press for the tile industry". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Buscar texto completoVyas, Saurabh y Venkata Dinesh Raju Jonnalagadda. "Modelling of Automotive Suspension Damper". Thesis, KTH, Fordonsdynamik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293498.
Texto completoEn hydraulisk stötdämpare spelar en viktig roll för att fordonets hantering och komfort. Attjustera och välja en stötdämpare baserat på subjektiv utvärdering, genom att beakta olika användares åsikter, skulle vara en ineffektiv metod eftersom användarnas komfortkrav varierarmycket. Istället föredras matematiska modeller av stötdämpare och simulering av dessa modellerunder olika driftsförhållanden för att standardisera inställningsförfarandet, kvantifiera komfortnivåerna och minska testkostnaden. Detta skulle kräva en modell som är tillräckligt bra för attfånga upp stötdämparens beteende under olika drifts- och extrema förhållanden.Force-Velocity (FV) -kurvan är en av de mest använda stötdämparmodellerna. Denna kurvaimplementeras antingen som en ekvation eller som en uppslagstabell. Det är ett diagram somredovisar den maximala kraften vid varje maxhastighetspunkt. Det finns vissa dynamiskafenomen som hysteres och beroende av stötdämparens förskjutning, som inte kan fångas med enFV-kurvmodell, men som krävs för att bättre förstå fordonets beteende.Denna avhandling genomfördes i samarbete med Volvo Cars i syfte att förbättra den befintligastötdämparmodellen som är en Force-Velocity-kurva. Detta arbete fokuserar på att utveckla enstötdämparmodell, som är tillräckligt komplex för att fånga upp de fenomen som diskuteratsovan och tillräckligt enkel för att implementeras i realtidssimuleringar. Avhandlingen syftarockså till att upprätta en standardmetod för att parametrisera spjällmodellen och generera ForceVelocity-kurvan från de test som utförts på stötdämpartestriggen. En testmatris som innehållerstandardtest för parametrisering och extrema testfall för validering av den utvecklade modellenkommer att utvecklas. Det sista fokuset är att implementera stötdämparmodellen i en multi-bodysimulation (MBS) programvara.Examensarbetet inleds med en introduktion, där bakgrunden för projektet beskrivs ochdärefter definieras målen med arbetet. Det följs av en litteraturöversikt där några avanceradestötdämparmodeller diskuteras i korthet. Därefter diskuteras en steg-för-steg-process för attutveckla stötdämparmodeller tillsammans med några fler möjliga alternativ. Senare diskuteraskonstruktionen av en testmatris i detalj följt av parameteridentifieringsprocessen. Därefterdiskuteras valideringen av den utvecklade stötdämparmodellen med hjälp av testdata från VolvoHällered Proving Ground (HPG). Efter validering presenteras implementeringen av modellen iVI CarRealTime och Adams Car tillsammans med resultaten. Slutligen avslutas rapporten medslutsatser från arbetet och rekommendationer för framtida arbete görs för att ytterligare förbättramodellen.
Dowell, Andrew. "Windpump modelling, starting hysteresis and the use of a low solidity rotor driving a mono pump through clutched transmission". Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409790.
Texto completoSameh, Ebong F. "Sorption of Ni and Eu to granitic rocks and minerals". Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/9324.
Texto completoZhong, Yiming. "Modelling sediment transportation and overland flow". Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:a45eefae-5a0f-4917-9abb-261ae792f2ee.
Texto completoMousavi, Seyedali. "Electromagnetic Modelling of Power Transformers for Study and Mitigation of Effects of GICs". Doctoral thesis, KTH, Elektroteknisk teori och konstruktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159747.
Texto completoQC 20150210
Lobosco, Vinicius. "On the Modelling of Mechanical Dewatering in Papermaking". Doctoral thesis, KTH, Fibre and Polymer Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3702.
Texto completoMost of the water fed into a paper machine is removedmechanically in the forming and press sections. One of thefactor which has an important influence on mechanicaldewatering, i.e. in both forming and pressing, is thestress-strain behaviour of the fibre network.
The focus of this thesis is on the development of improvedmathematical descriptions of the stress-strain behaviourexhibited by fibre networks in the forming and press sections.The first part of the thesis presents a physically based modelof the forming and densification of fibre mats in twin-wireformers. The model can calculate the ecect of the applicationof a varied load through the forming section. It was developedfrom mass and momentum balances of the fibre and liquid phases,the fibre mat stress-porosity relation and an expression forthe permeability as a function of the porosity. The fibre-matstress-porosity relation used is rate-independent and presentshysteresis. Simulations have been conducted to study theeffects of roll pressure, blade pulses, wire tension andbeating. The effect of sequential blade pressure pulses afterthe forming roll on the dewatering and the concentrationgradients could be characterised. The simulations alsoexhibited rewetting by expansion when the fibre mats left theforming roll. Increasing wire tension resulted in increaseddewatering, but the rate of increase diminished rapidly withincreasing tension. The simulation results also indicated thatbeating has a large influence on dewatering.
The second part of the thesis presents two models of therate-dependent stress-strain behaviour of the fibre networkthat is observed in wet pressing. The first model was based onthe approach pioneered by Perzyna (1966) for strain-ratedependent plasticity and was quite satisfactory for calculatingthe stress-strain behaviour of the fibre network in singlepress nips. It was successfully applied for studyingdensification and dewatering in both normal wet pressing andhigh temperature wet pressing. However, the first model onlyincludes rate dependence in the compression phase of thecompressionexpansion cycle; the expansion phase is treated asbeing rate independent
The second model of the stress-strain behaviour of the fibrenetwork treats both compression and expansion as being ratedependent, according to experimental observations. It is basedon the idea that the wet fibre web may be conceived as alayered network of restricted swelling gels. A swollen fibre isa restricted gel, the inner swelling pressure in a swollenfibre wall being balanced by the stresses in the fibre wallstructure. The observed rate dependence of wet webs in bothcompression and expansion phases was attributed to the flow ofwater out of and into the fibre walls. The second model gavepredictions that are in good agreement with results fromuniaxial experiments using pressure pulses of arbitrary shapefor both a single pulse and a sequence of pulses. It maytherefore be used as a general model for the rheologicalbehaviour of the wet fibre network in wet pressing, providedthe model parameters are estimated from experimental data withsmall experimental error.
KEYWORDS:Paper, modelling, dewatering, forming, wetpressing, fibre network stress, rheology, hysteresis,intra-fibre water, compressibility, structural stress,stress-strain, restricted gels, swelling.
Barnes, Gary James. "Computational modelling for type-II superconductivity and the investigation of high temperature superconducting electrical machines". Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365887.
Texto completoBanks, Alan James. "Effects of rear bumper beam deletion on the perception of steering performance of commercial vehicles". Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14405.
Texto completoBanks, Alan J. "Effects of Rear Bumper Beam Deletion on the Perception of Steering Performance of Commercial Vehicles". Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/14405.
Texto completoEludoyin, Adebayo Oluwole. "Modelling the hysteretic patterns of solute concentration-discharge relationships and their significance for hydrological pathways at the farm-scale". Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/15374.
Texto completoWei, Sicong. "A 3D Sliding Bearing Finite Element Based on The Bouc-Wen Hysteretic Model : Mathematical modelling and numerical implementation". Thesis, KTH, Bro- och stålbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-289480.
Texto completoWolfbrandt, Anna. "AC losses in HTS as a function of magnetic fields with arbitrary directions". Doctoral thesis, KTH, Electrical Systems, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-35.
Texto completoAlthough a superconductor has zero resistivity when carrying a direct current, losses do occur when it is exposed to an alternating magnetic field and/or is carrying an alternating current. The magnitude of these so-called AC losses depends on the operating temperature, the amplitude and the direction of the magnetic field, the transport current, and the frequency. Therefore, the use of high-temperature superconductors, HTSs, in electric power components such as cables, transformers or reactors, requires knowledge of the AC losses.
This thesis deals with the development of AC loss models for HTSs, mainly for Bi-2223 tapes. In particular, the orientation of the applied magnetic field is taken into account in the modelling. The basis for the models is the results of experimental investigations.
The basic concepts of HTSs with special emphasis on the modelling of AC losses are presented. These can be broken down into several components. Their sources and natures are described. One of the components is the hysteretic loss and it is the dominating loss in AC applications at power frequencies. Therefore, the other loss components are neglected in the modelling.
Models are presented and the associated parameters are investigated with respect to their dependence of the magnetic field as well as the temperature. The AC losses for parallel and perpendicular magnetic field with respect to the wide side of the tape are calculated numerically. Moreover, a semi-empirical model for intermediate angels of the applied magnetic field is proposed. The comparisons show good agreement with experimental results.
Keywords: High-temperature superconductors, AC loss modelling, hysteresis, E-J characteristic.
Fagerlund, Fritjof. "Experimental and Modelling Studies on the Spreading of Non-Aqueous Phase Liquids in Heterogeneous Media". Doctoral thesis, Uppsala universitet, Institutionen för geovetenskaper, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7430.
Texto completoFlerfasföroreningar innefattar vanligt förekommande organiska vätskor som bensin, dieselolja och klorerade lösningsmedel. Spridningen av dessa föroreningar i mark är komplicerad och styrs av det samtidiga flödet av organisk vätska, vatten och markluft samt utbytet av komponenter (föroreningar) mellan de olika faserna. Detta arbete syftade till att utveckla nya metoder och modeller för att studera spridningen av flerfasföroreningar i mark: (i) En metodik utvecklades för att i laboratorium noggrant och kontinuerligt mäta hur en organisk vätska är rumsligt fördelad i en tvådimensionell experimentuppställning. Metoden baserades på röntgenutsläckning för olika energinivåer. (ii) Infiltration av organisk vätska i vattenmättade medier studerades för olika konfigurationer av geologisk heterogenitet. I experimentuppställningen packades olika sandmaterial noggrant för att konstruera en välkänd, stokastiskt heterogen struktur. Spridningsprocessen dokumenterades i tre detaljerade mätserier och heterogenitetens påverkan på flöde och kvarhållning av den organiska vätskan påvisades. (iii) Experimenten simulerades med en numerisk modell. Olika modeller prövades för att beskriva de grundläggande relationerna mellan kapillärtryck (Pc) vätskehalt (S) och relativ permeabilitet (kr) för detta tvåfassystem av vatten och organisk vätska. En relation infördes för att beskriva partiell orörlighet hos den organiska vätskan i porer vars halsar tillfälligt blockeras av vatten då mediet avvattnas. Vikten av att i de grundläggande relationerna ta hänsyn till hysteresis och kvarhållning av organisk fas visades. (iv) Olika Pc-S-kr relationer för trefassystem av vatten, organisk vätska och markluft testades mot befintliga experimentella data. En ny relation för hur slingrigheten (eng. tortuosity) beror av vätskehalten infördes i kr-S relationen och olika möjligheter för att skala Pc-S relationen analyserades. (v) En modelleringsmetodik utvecklades för att studera spridningen av flerkomponentsföroreningar. Med metoden kunde spridningsbeteendet hos enskilda, särskilt skadliga komponenter som t.ex. bensen särskiljas då ett bensinutsläpp i samband med en transportolycka simulerades.
Gravelle, Richard. "Temporal variability of meltwater and sediment transfer dynamics at an Arctic glacier, Storglaciären, northern Sweden". Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14412.
Texto completoLoffredo, Nicolas. "Devenir du séléniate dans les sols : mise en évidence expérimentale et modélisation des phénomènes d'hystérèse de sorption/désorption". Phd thesis, Université du Sud Toulon Var, 2011. http://tel.archives-ouvertes.fr/tel-00608532.
Texto completoBhave, Tejas N. "Effect of Material Nonlinearity on Rubber Friction". Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou14798628516789.
Texto completoVašina, Michal. "Kovy s tvarovou pamětí - modelování nelineárních systémů s hysterezí". Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-364606.
Texto completoViéville, Émilie. "Caractérisation et modélisation du comportement mécanique d'éléments d'étanchéité par presse garniture". Thesis, Lorient, 2018. http://www.theses.fr/2018LORIS482/document.
Texto completoThe impact of fugitive emissions leakage rate on the environment is an essential issue for industries. Therefore, many regulations and standards are created to prevent risks and to limit their impacts. One of these major sources of fugitive emissions comes from industrial valves. In the Valve Industrie, the tightness of stem are often ensured by stuffing box seal. In the energy sector, the tightness could be ensure with compression packing which is manufactured in exfoliated graphite; which is a relatively flexible material, endorsed for its characteristics and having a particular macroscopic structure. The aim of this study is to improve the knowledge of the complex mechanical behaviour of compression packing in exfoliated graphite. The aim is to determinate the mechanical behaviour of these packings in order to predict their tightness. To characterize this behaviour, various test campaigns are conducted on seals in situation. Thus, based on an existing apparatus and a device developed specifically for this study, the characterization of this kind of packing is performed through loading-unloading and cyclic compression tests. A numerical model which is able to describe a complexe mechanical behaviour of compression packing, is performed thanks to resulting database. This Hyperelasto-Hysteresis phenomenological model corresponds to an additive decomposition in stress with an hyperelastic contribution and an hysteretic contribution. The comparison of the experimental and numerical responses of the seal, as part of the study a single seal but also of a packing, is discussed
Maaroufi, Maroua. "Modélisation des transferts hygrothermiques dans les matériaux de construction : incidence de l’hystérésis". Thesis, La Rochelle, 2019. http://www.theses.fr/2019LAROS028.
Texto completoThe present work aims to study the influence of the sorption hysteresis phenomenon on heat and moisture transfer in building materials. In order to achieve this, we first describe the microstructure of materials, which will allow a better understanding of their behavior at the macroscopic scale. Subsequently, numerical simulations of the coupled heat and mass transfers will be conducted, taking into account the real microstructure of the materials using X-rays reconstructed 3D volumes. Several imaging techniques have been used to obtain a fine description of the microstructure of polystyrene concrete and its different phases. The 3D reconstructions of the actual volume were obtained using X-rays micro-tomography, which showed its complex microstructural heterogeneity. Afterwards, we carried out a campaign of macroscopic experimental characterization of the material. It included the determination of the physical and hygrothermal properties of the polystyrene concrete, as well as the impact of temperature and relative humidity on these same properties. Polystyrene concrete shows excellent performance in thermal insulation and heat storage. Later, experiments have been set up in order to better understand the moisture transfer in samples subjected to cyclic stresses, in order to highlight the sorption hysteresis effect. A model of coupled heat and moisture transfers has been developed, taking into account the effect of sorption hysteresis and thus including the hydric history of the material. The results of the numerical simulations were compared to the experimental ones and showed a good match. 3D simulations will be performed on the actual volumes reconstructed by tomography to take into account the heterogeneity of the material
Frias, Anthony. "Minimisation des pertes fer des machines électriques de traction par la modélisation et l'optimisation". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAT028/document.
Texto completoCost, range and lifetime are the main aspects that hold back the consumer to buy electric cars. These three aspects are all related to the battery which stores a limited amount of energy. Under such condition energy consumption is a major concern in electric cars. As the major electricity consumer, electrical machines play a key role for global energy savings. In this context how the electric machine can be made more energy efficient? To answer this question this thesis aim to model (accurately enough) and reduce the iron losses in traction electrical machine for electrical car. Indeed iron loss model suffer from a lack of confidence when it comes to fine optimization during the late phase of development. This thesis answers this question and takes into account the development criteria of the car industry and the constraints of the electric car. The first part of the thesis gives an overview of the application by taking a wounded rotor synchronous machine as a case study. The reader will discover the electrical machine with a soft magnetic material perspective. First, conclusion show that fine modelling of the electric machine is necessary to achieve desired accuracy. An overview on soft magnetic material behavior and measurements is then given. The reader will then acquire a broad feeling on soft magnetic material behavior and understands the first source of inaccuracy of the models (the measurements). Then, the typical models for predicting iron losses in magnetic materials are presented in a literature review. The second part of this study focus on iron loss modelling aspect. The loss surface model (a scalar hysteresis model made of a static and dynamic contribution) is used as the base of this modelling work. The static contribution is re-developed using Everett function formulation of the Preisach model is used to allow easy identification of the model directly from measurements. The identification of the dynamic contribution is re-worked to allow identification from sine-wave measurements (triangular wave measurement previously required). The model accuracy is improved and validated on 63 test cases with high harmonic distortion wave forms. The iron loss model is then coupled to finite element model of the electric machine and the limits of the model are investigated. One of the limits coming from measurement limitation, a methodology to evaluate the relevance of the measurement range is proposed. A literature review of the main impact of the process including cutting, stacking and assembling effects on electrical steel magnetic characteristics is intended to complement the modelling work to help the decision making of the designer on aspects that cannot be modeled. Finally methodologies playing with the modelling hypothesis and involving design of experiment and response surface are presented to reduce computational time and allow the optimization of the control of the machine. The optimizations carried out show total machine loss reduction up to 50% for some working point of the machine compared to an optimization dedicated to minimize only Joule's losses. This results show the interest of using a reliable iron loss model to reduce the total loss of the machine
Petrášová, Anna. "Počítačové modelování teplotní hystereze při změně skupenství". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445463.
Texto completoGupta, Bhaawan. "Advanced electromagnetic non-destructive testing on creep degraded high chromium ferritic steels : Characterization, Modelling and physical interpretation". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI074.
Texto completoUnder constant high temperatures and pressure, the material undergoes mechanical creep degradation which leads to microstructural changes. These microstructural changes if not monitored on time, can lead to some serious fatal accidents such as in power plants. To investigate these microstructural changes, the material has to be shaped in a certain specific shape and size to have the imaging analysis using Scanning electron microscopy, Electron backscatter diffract ion etc. which are destructive in nature and involve high equipment cost. In order to overcome this issue, this thesis work, incorporates three different non-destructive techniques, to study the evolution of magnetic signatures with respect to the level of rupture they are exposed to. It is legitimate to assume that all the microstructural changes that occur in the material can be reflected in the corresponding magnetic signatures measured. The material that has been studied here is high chromium creep degraded steel which is used in the thermal power plant. The magnetic signatures are evaluated in terms of microstructural information to draw the conclusions. Some magnetic parameters from the curves, such as coercivity, magnetic reversibility are derived which show strong correlations with the microstructure. Similarly, techniques based on Hysteresis curves, and magnetic Barkhausen Noise are also implemented. To further quantify the results obtained from the magnetic signatures of the materials, a model has been developed to derive model parameters in order to physically interpret the microstructural changes. The modelling technique will help in overcoming the issue of lack of standards in NDT, irrespective of the experimental set-up involved. The parameters are compared to reveal sensitivity based on the technique. Finally, conclusion has been drawn to check which parameters are correlated to microstructure for a particular NDT technique used
MEHRPARVAR, MAHSHID. "Control Systems for Experimental Magnetic Materials Characterization Using Dynamic Preisach Models". Thesis, KTH, Elektrisk energiomvandling, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-160704.
Texto completoVerkningsgraden for elmotorer ar av okande intresse pa grund av deras omfattande anvandning och vaxande oro for globala energiforbrukningsfragor. Jarnforluster har ett stort inytande i de totala forlusterna och ar darfor ett viktigt omrade for forskare och tillverkare av elektriska motorer. Jarnforlusterna beror till stor del av det magnetiska materialet som anvands i konstruktion av elmotorer och det ar darfor nodvandigt att identiera materialets egenskaper. I det har arbetet beskrivs utvecklingen av ett reglersystem for att inducera en ren sinusformat magnetisk odestathet i ett magnetiskt material. Detta ar nodvandigt for att kunna bestamma det magnetiska materialets egenskaper under kontrollerade forhallanden. Huvudsvarigheten ar det icke-linjara sambandet mellan magnetiska faltstyrkan och odest atheten. Sambandet formar en hysteres och for att eliminera dess inytande anvandes en matematisk invers model. For att hitta en lamplig model genomfordes en literaturstudie och Preisach modellen och dess dynamiska utokning valdes. I detta arbete nns en detaljerad beskrivning av bade teorin bakom modellen och dess implementering. Modellen utvarderades genom att jamfora matvarden med simulationsresultat for olika magnetiska material. I sista delen av detta arbete kombineras inversmodellen med ett reglerssystem for att kunna uppna en sinusformat odestathet i det magnetiska materialet. Tva olika regleralgoritmer utvarderas, en enklare PI-regulator och en regulator som inkluderar en sa kallat "Disturbance Observer" (DOB). DOB:n anvandes for att observera felet som uppstar vid invertering av hysteresen och for att korrigera felet. De bada regulatorernas formaga attaterskapa en ren sinusformat magnetisk odestathet testas genom att genomfora simulationer for olika magnetiska material vid varierande frekvenser.
CARNEVALE, DANIELE. "Hysteresis modeling for smart materials and observer design for 2DOF robots". Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/612.
Texto completoNehme, Zeinab. "Nanoparticules magnétiques d’architecture complexe core-shell : couplage d'échange bias et interaction dipolaire". Thesis, Le Mans, 2016. http://www.theses.fr/2016LEMA1019.
Texto completoThis thesis is dedicated to the numerical study by means of Monte Carlo (MC) simulations of core@shell Fe3O4@CoO magnetic nanoparticles (NPs) presenting exchange bias properties (EB). In particular, we focused our study on the effect of collective responses (inter-particle interactions as dipolar interactions (DI)) on the magnetic properties of these structures. Our numerical work is motivated by some preliminary experimental results showing the existence of a relationship between the hysteresis loop shift (exchange bias field) and the interaction between NPs. The first part of this thesis is a methodological study to figure out the optimal conditions to simulate hysteresis loops correctly by MC. The results reveal that the coercive field Hc is linearly related to the effective anisotropy constant for non-biased conditions (free algorithm, cone algorithm, mixed algorithm). The second part is dedicated to the study of exchange-biased nanostructures at the atomic scale. We have been able to reproduce both characteristics of EB (hysteresis loop shift, significant increase in Hc). A method allowing the evaluation of the effective anisotropy has been proposed. Considering an assembly of nanoparticles, several models are studied. The experimental results are interpreted according to the degree of aggregation of NPs. It was shown that the aggregation (exchange interactions between NPs) has a direct effect on the exchange bias field, but the role of the ID on the exchange field requires complimentary calculations to be clarified
Orgéas, Laurent. "Étude expérimentale et numérique du comportement thermomécanique d'un alliage à mémoire de forme industriel NiTi". Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10256.
Texto completoGAVIOLI, CHIARA. "Nuove prospettive in modelli di transizione di fase". Doctoral thesis, Università degli studi di Modena e Reggio Emilia, 2021. http://hdl.handle.net/11380/1237395.
Texto completoPhase transitions occur in many relevant processes in physics, natural sciences, and engineering: almost every industrial product involves solidification at some stage. Examples include metal casting, steel annealing, crystal growth, thermal welding, freezing of soil, freezing and melting of the earth surface water, food conservation, and others. All of these processes are characterized by two basic phenomena: heat-diffusion and exchange of latent heat of phase transition. In this thesis, which consists of four distinct parts, we deal with phase transitions from different points of view. The first part, titled "Control and controllability of PDEs with hysteresis with an application in phase transition modeling", is a bridge between controllability of PDEs with hysteresis and phase transitions. Indeed, thanks to the special link between hysteresis operators and phase transitions, the controllability results that we prove can be applied to the so-called relaxed Stefan problem. This is an example of a basic model of phase transition, since it simply accounts for heat-diffusion and exchange of latent heat. More complicated models, which take into account also the mechanical aspects of the process, are considered in the second and in the third part. More precisely in the second part, titled "A viscoelastoplastic porous medium problem with phase transition", we derive and investigate a model for filtration in porous media which takes into account the effects of freezing and melting of water in the pores. The third part, whose title is "Fatigue and phase transition in an oscillating elastoplastic beam", is devoted to the derivation and the study of a model describing fatigue accumulation in an oscillating beam under the hypothesis that the material can partially recover by the effect of melting. Finally, in the fourth part, titled "Regularity for double-phase variational problems", we address the problem of the higher differentiability of solutions to the obstacle problem. In particular we deal with the case of non-standard growth conditions, which includes the so-called double-phase functionals. Such functionals describe the behavior of strongly anisotropic materials whose hardening properties drastically change with the point, hence they exhibit the most dramatic phase transition. The techniques here employed are different from those used in the rest of the thesis, since they rely on the direct methods pertaining to the regularity theory in the field of Calculus of Variations.
Trutalli, Davide. "Insight into seismic behaviour of timber shear-wall systems". Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424481.
Texto completoQuesta tesi di dottorato è il risultato di tre anni di attività di ricerca in ambito ingegneristico strutturale applicato allo studio di sistemi costruttivi innovativi in legno. Il principale obiettivo è quello di fornire un contributo alla ricerca scientifica internazionale e ai metodi attuali di progettazione in merito alla risposta sismica di sistemi in legno a pareti sismo-resistenti, i quali rappresentano tutt’ora un’innovazione nel settore delle costruzioni e si stanno diffondendo grazie alle loro caratteristiche favorevoli. Una panoramica iniziale sull’utilizzo dei principali sistemi strutturali in legno in zone sismiche per la realizzazione di edifici bassi o di media altezza viene fornita e contestualizzata nella vigente normativa sismica europea. La prima parte della tesi affronta il tema della progettazione sismica di sistemi a pareti in legno, con particolare attenzione ai criteri di modellazione lineare e non lineare, proponendo diverse strategie ed evidenziandone le caratteristiche. In questa parte vengono forniti inoltre definizioni e concetti fondamentali propri dell’analisi sismica di strutture in legno. Un’attenzione particolare è riservata alla definizione e applicazione del “capacity design”, sottolineandone lo stretto legame con il concetto di fattore di struttura. Viene proposta infine una definizione del fattore di struttura come prodotto tra una parte intrinseca alla struttura e una sovraresistenza di progetto. Tale definizione permette di caratterizzare i sistemi strutturali con la propria capacità dissipativa e di valutare separatamente la riserva di sicurezza introdotta dalla progettazione. La seconda parte della tesi analizza il comportamento strutturale della tecnologia X-Lam (CLT), che rappresenta uno dei più comuni sistemi strutturali in legno. In questa parte vengono approfonditi i concetti di duttilità, capacità dissipativa, regolarità e irregolarità applicati al sistema X-Lam. La risposta sismica e la capacità dissipativa di questo sistema sono state preliminarmente valutate tramite una procedura analitico-sperimentale. Modelli numerici non-lineari hanno quindi permesso di valutarne la capacità dissipativa intrinseca in funzione delle variabili costruttive proprie del sistema. I risultati mostrano come le decisioni costruttive in fase di progettazione influenzino la risposta sismica dell’edificio; ciò è in contrasto all’applicazione di un unico valore del fattore di struttura per l’intera tecnologia X-Lam. Un’analisi statistica applicata a tali risultati numerici ha consentito di proporre formulazioni analitiche per il fattore di struttura per edifici regolari in funzione delle caratteristiche dell’edificio stesso. Infine, le stesse analisi condotte su edifici non regolari in altezza hanno fornito un coefficiente per tenere in conto della riduzione di capacità dissipativa a causa dell’irregolarità. Nella terza parte viene presentata un’applicazione della tecnologia X-Lam per costruire edifici alti, analizzando il comportamento di edifici snelli con nucleo sismo-resistente e pareti aggiuntive perimetrali. Vengono riportati inoltre le principali limitazioni e inconvenienti nel realizzare tali strutture in aree caratterizzate da elevata intensità sismica e le loro implicazioni nella progettazione. La parte finale descrive e analizza tre sistemi strutturali in legno innovativi, come alternative a tecnologie più comuni, quali X-Lam o platform-frame. Questi sistemi, soggetti ad azioni sismiche, sono caratterizzati da una capacità deformativa e dissipativa diffusa, al contrario del sistema X-Lam in cui tale capacità è concentrata principalmente negli elementi di connessione. Questa risposta differente è studiata attraverso test sperimentali quasi statici e simulazioni numeriche. In dettaglio, sono presentati e analizzati due sistemi a pareti massicce stratificate; realizzate senza l’uso di colla tra gli strati e una parete ibrida acciaio-legno con un sistema innovativo di controvento.
Piedrafita, Francos Daniel. "Designing, testing and modelling two innovative non-conventional buckling restrained braces for seismic resistant buildings". Doctoral thesis, Universitat de Girona, 2014. http://hdl.handle.net/10803/284738.
Texto completoEn la present tesi, dos BVR totalment metàl·lics s’han dissenyat, fabricat i assajat, satisfent tots dos els requeriments dels protocols definits per les normes europees i americanes. Estan formats per un element de travat ranurat que estabilitza el nucli metàl·lic. El primer d’ells, el Braç de Vinclament Restringit Modular (BVRM), està format per diversos mòduls seriats que a la vegada contenen diverses unitats de dissipació, que plastifiquen sota esforços tallants, connectades en paral·lel. Tot i que té un bon comportament histerètic i una gran ductilitat, el nucli és pesat i difícil de fabricar. El segon braç, anomenat Braç de Vinclament Restringit Ranurat (BVRR), soluciona aquests inconvenients. Plastifica sota esforços axials, de la mateixa manera que els BVR convencionals, però el nucli massís és substituït per una platina perforada. Aquest nucli consisteix en un únic element composat per dos bandes laterals, dissenyades per a plastificar i amb una secció quasi constant, connectades per diversos ponts estabilitzadors que es mantenen sempre en el seu rang elàstic. Aquests ponts, juntament amb l’element de travat, impedeixen el vinclament de les bandes laterals. S’han proposat diverses expressions de disseny pels dos braços. S’ha formulat i implementat, en un programa d’elements finits comercial, un model de material per a simular numèricament el comportament dels braços, reduint així la dependència dels assajos a escala real durant el seu procés de disseny
Marchi, Luca. "Innovative connection systems for timber structures". Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3424736.
Texto completoLe connessioni e gli elementi di fissaggio svolgono un ruolo essenziale nella determinazione della resistenza, stabilità e solidità, ovvero nella risposta globale delle strutture del legno. In particolare, le connessioni soggette a carichi statici devono essere studiate in termini di resistenza e rigidezza, mentre quelle progettate per resistere a carichi ciclici (ad es. sismici), necessitano anche della completa definizione della loro risposta isteretica. Questa tesi si concentra sul comportamento dei collegamenti moderni sviluppati e impiegati nell'ingegneria del legno. Una prima panoramica sulle connessioni meccaniche impiegate nelle strutture del legno e la loro evoluzione è riportata nella sezione introduttiva di questa tesi. Vantaggi e criticità delle connessioni tradizionali sono le motivazioni dell’evoluzione e dei miglioramenti prodotti dalle connessioni innovative. Vengono analizzate e discusse due diverse applicazioni di connessioni per strutture in legno, ognuna delle quali espone aspetti e problematiche diverse. Il primo afferma di dare una panoramica delle moderne viti utilizzate nelle strutture composte legno-calcestruzzo (TCC), dove l'obiettivo principale è ottenere massima resistenza e ancor più rigidezza. Il secondo, è incentrato direttamente nell’analisi delle prestazioni cicliche delle connessioni moderne utilizzate nelle strutture in CrossLam (CLT) in cui la capacità dissipativa e lo smorzamento strutturale sono della massima importanza. Di conseguenza, il presente manoscritto è suddiviso in due parti principali. La prima parte riguarda le giunzioni legno-calcestruzzo realizzate con viti moderne. Il punto chiave per garantire prestazioni meccaniche adeguate a queste strutture composite è l'utilizzo di connettori caratterizzati da un'adeguata resistenza e rigidezza tra trave di legno e soletta di calcestruzzo, indipendentemente dalla presenza di uno strato intermedio. I connettori cilindrici moderni, come le viti autofilettanti, possiedono un crescente interesse perché combinano elevate prestazioni, se è sfruttata la loro elevata capacità ad estrazione, e rapidità di esecuzione. In questo lavoro viene proposto un approccio teorico semplificato per calcolare la resistenza al taglio e la rigidezza dei giunti TCC realizzati con viti inclinate e poi confrontato con le attuali procedure di progettazione. Inoltre, viene fornito un rapporto sulle prove di push-out a breve termine di giunti TCC realizzati con viti autofilettanti inclinate, effettuate con vari tipi di fissaggio, diametro e tipo di calcestruzzo. Di conseguenza, viene anche riportato un confronto tra i risultati ottenuti con il metodo teorico e le prove sperimentali e viene discusso criticamente in termini di forza e rigidezza. L'ultima sezione della prima parte comprende la progettazione di un connettore innovativo che combina l'utilizzo di viti autofilettanti e polimero termoplastico rinforzato con fibra di vetro (GFRP) per realizzare giunti TCC strutturali. Gli FRP vengono utilizzati nell’ingegneria civile da decenni, ma la maggior parte di queste applicazioni utilizza compositi termoindurenti pre-impregnati, il più comune dei quali è il polimero rinforzato in fibra di carbonio (CFRP). Al contrario, i materiali termoplastici sono relativamente nuovi e mancano di storia nell'utilizzo nell'infrastruttura civile. Le simulazioni numeriche, effettuate per progettare questo giunto, sono descritte in dettaglio. Quindi, i risultati delle prove sperimentali condotte per esaminare il comportamento del dispositivo sottoposto a condizioni di carico di taglio sono confrontati con le previsioni analitiche descritte. La seconda parte di questo lavoro si concentra sullo sviluppo di collegamenti innovativi impiegati per le strutture in CLT. La prestazione sismica degli edifici CLT è principalmente legata alla capacità dei collegamenti di plasticizzarsi, poiché gli elementi del legno hanno una capacità limitata di deformazione inelastica. Oggi, l'utilizzo di connessioni quali hold-down e angolari, originariamente sviluppati per costruzioni tipo platform-frame, è stato esteso anche agli edifici CLT. Tuttavia, la capacità di dissipazione degli edifici a telaio è diffusa soprattutto nella connessione telaio-pannello, mentre nelle strutture in CLT il contributo dissipativo è assicurato esclusivamente da connessioni duttili che collegano i pannelli. La necessità di una connessione più affidabile che fornisca un comportamento isteretico prevedibile ed affidabile, un fenomeno ridotto di “pinching” (causato dal rifollamento del legno) e una degrado di resistenza giustifica lo sviluppo continuo di connessioni "innovative". In questo lavoro è stato progettato e valutato un elemento di connessione che sormonti i problemi sopradescritti e che lavora sia per i carichi di trazione che per taglio, e ne vengono discussi gli aspetti più significativi. Inizialmente viene illustrata la procedura di progettazione dell'elemento di connessione e dei test sperimentali preliminari che convalidano le previsioni numeriche. Successivamente vengono descritte le fasi di progettazione e test di ulteriori versioni migliorate delle staffe dissipative e sono riportati i loro risultati sperimentali facendo particolare attenzione nel descrivere la loro risposta isteretica e il dominio di resistenza tensione-taglio. Un ruolo importante in questo lavoro è dato all'applicazione dei criteri di gerarchia delle resistenze (progettazione in capacità) a livello di connessione al fine di garantire il miglior sfruttamento della capacità dissipativa della connessione. Di conseguenza, vengono forniti concetti teorici che descrivono l’applicazione di tali concetti a connessioni tradizionali e innovative, e confermate da prove sperimentali delle staffe oggetto di studio ancorate a un pannello CLT. Infine, i risultati di simulazioni numeriche dettagliate e prove cicliche quasi-statiche sono state utilizzate per sviluppare un modello di macro-elemento implementato in un codice numerico che ha permesso di determinare le prestazioni sismiche di un edificio caso studio in CLT realizzato con tali connessioni. Con questi due esempi la presente tesi mira a definire un originale procedura di valutazione delle performance delle connessioni innovative per legno, combinando l'uso di modelli teorici, numerici ed analisi sperimentali e mettendone in evidenza le differenze emergenti rispetto all'impiego di sistemi di connessioni tradizionali.
Song, Tiancheng. "Modelling hysteresis in magnetically ordered materials". 2003. http://hdl.handle.net/1993/20058.
Texto completoSaghafifar, Mahmoud. "Magnetic hysteresis modelling using knowledge based engineering techniques". 2004. http://arrow.unisa.edu.au:8081/1959.8/24959.
Texto completothesis (MEng(ElectronicsEngineering))--University of South Australia, 2004.
Scheffler, Gregor A. [Verfasser]. "Validation of hygrothermal material modelling under consideration of the hysteresis of moisture storage = Validierung hygrothermischer Materialmodellierung unter Berücksichtigung der Hysterese der Feuchtespeicherung / submitted by Gregor Albrecht Scheffler". 2008. http://d-nb.info/989010376/34.
Texto completoJacobs, Daniel Anthony. "Device Modelling of Perovskite Solar Cells". Phd thesis, 2018. http://hdl.handle.net/1885/151935.
Texto completoRai, B. Umesh. "Bond Graph Model Of A Generalised Multiphase Electromagnetic Device With Magnetic Non-idealities". Thesis, 2010. http://etd.iisc.ernet.in/handle/2005/2229.
Texto completoSingh, Vikrant. "Modeling Of Liquid Flow In A Packed Bed Under Influence Of Gas Flow". Thesis, 2006. http://hdl.handle.net/2005/409.
Texto completoLong, Lu Yann y 呂彥龍. "Use of Transformed Hysteretic Damping in Modelling Axial Loading ile". Thesis, 1994. http://ndltd.ncl.edu.tw/handle/62011751580455263812.
Texto completo淡江大學
土木工程研究所
82
The purpose of this research is to establish a new damping model of soils for dynamical solution using the integration technique With the hysteretic type of damping ratio determined from the laboratory dynamic tests varying frequencies , a time dependent equivalent viscous coefficient can be obtained using the Fourier Integral . By doing so , the typical viscous coefficient ( or in a matrix form ) , representing energy absorbing ability of the soils and perhaps for the energy dissipation along the structure in more detailed form , can then be used in the analytical studies . Research work conducted herein is modeled with the behavior of axial loaded pile . Comparison are made with the use of traditional modelling. It is found that the prediction of the model is as good as that of the convention . Moreover , the proposed modification of frequency dependent soil damping eliminate the possible interference of numerical shortcoming at high frequencies .