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Vliv podvozku na tahové vlastnosti traktorů / The influence of the chassis on drawbar properties of tractorsChmelař, Zdeněk January 2015 (has links)
In this master thesis is analyzed the current situation in the construction chassis of tractors, in addition, a methodology for evaluating the impact of influences on drawbar properties of tractors. The main objective of this work was to analyze and conclude the measured drawbar properties of selected tractor same power and weight categories with different chassis designs. Measured and calculated values were tabular and graphically presented. When evaluating the drawbar properties were determined according tractive power and slip depending on the drawbar forces.
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Imagerie microsismique d’une asperité sismologique dans la zone de subduction Équatorienne / Microseismicity around an asperity in the Ecuadorian subduction zoneSegovia Reyes, Mónica 25 November 2016 (has links)
La zone de subduction centrale en Equateur est caractérisée par un patch fortement couplé, pas de grands séismes connus et de fréquents essaims sismiques, dont certains associés à des épisodes de glissements lents (SSE). Les hypocentres déterminés sur un réseau temporaire dense onshore-offshore image la sismicité de fond et plusieurs essaims (01/2013), synchrones d’un SSE (Mw´ 6.3). Une sismicité permanente se produit à 20-30 km de profondeur, proche et sous la zone de contact interplaque (ZCI), bordant la partie profonde de la zone couplée. Les essaims superficiels (10 km) ont lieu sur des zones de failles crustales de la plaque plongeante (ZFC-Nazca), inverses, sub-verticales et qui bordent un massif océanique en subduction. Le SSE 2012-2013 est un événement composite se développant sur 2 patchs distincts. Le premier patch (P1), plus petit, se localise sur une partie peu couplée de la ZCI et le second (P2), plus superficiel, sur une zone fortement bloquée (>70%). Depuis le 25/11 et durant ~1,5 mois, sans sismicité, P1 se déverrouille progressivement, indiqué par un glissement discontinu, lent et faible. Le 13/01, l'accélération soudaine du glissement sur P1 réactive une ZFC-Nazca (1er essaim), située immédiatement updip P1 et downdip P2, ce qui favorise le début d´un glissement rapide, fort et continu sur P2 (et sur P1). Nous proposons que les fluides, expulsés par l'activité sur la ZFC-Nazca et injectés au niveau de la ZCI, contribuent à modifier le comportement de stabilité des matériaux, favorisant ce SSE inattendu sur une zone fortement bloquée. Environ 80% du moment asismique total sont libérés sur P2 en une semaine, concomitant d´essaims sur différentes ZFC-Nazca / The central subduction zone of Ecuador is characterized by a highly coupled patch, no known large earthquakes and frequent seismic swarms, some of them associated to slow slip events (SSE). The earthquakes recorded on a temporal onshore-offshore network show an unprecedented image of the background seismicity and of several intense swarms in early 2013, concomitant of a SSE (6.3 Mw). The 20-30 km deep permanent seismic clusters develop near and below the interface contact zone (ICZ), contouring the downdip limit of the locked area. The shallower swarms (10 km depth) occur on sub-vertical inverse crustal fault zones of the Nazca plate that seem to bound a known oceanic massive in subduction. The 2012-2013 SSE is a composite event developing on 2 distinct patches. The first and smaller patch (P1) is sited on an intermediate coupled portion of the ICZ than the shallower second patch (P2) that lies on a highly locked area (> 70%). Since 2012 Nov. 25 and during ~1.5 month, without seismicity, P1 progressively unlocks as revealed by the slow, low and intermittent slip. On 2013 Jan. 16, the sudden slip acceleration on P1 activates a Nazca crustal fault zone (first swarm) located immediately updip P1 and downdip P2, which in turn favors the onset of the faster, higher and continuous slip on P2 (and on P1). We propose that the fluids expelled by the fault activity and injected above, within the ICZ, contribute to modify the material stability behavior and favor the unexpected SSE on a highly locked area. About 80% of the total aseismic moment is released during one week on P2, at the same time than intense seismic swarms on distinct Nazca crustal fault zones
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Slip length of the tribo system steel-polyalphaolefin-steel determined by a novel tribometerCorneli, Tobias, Ludwig, Gerhard, Pelz, Peter F. January 2016 (has links)
Nowadays sealing systems are commonly designed by means of hydrodynamic and elastohydrodynamic theories. Although the analytical as well as the computational approaches have improved in meaning full manner since the last decades: For small sealing gaps, in the order of micrometers and below, a discrepancy between experimental investigated and theoretically predicted leakage flows occur. As a cause for the discrepancy a breakdown of the no slip boundary condition is suspected. Since in small sealing gaps the continuum hypothesis is violated and molecular effects have to be considered. One fundamental quantity to take molecular affects into account is the slip length. Within this paper a new measurement apparatus to evaluate the slip length for hydraulic applications is presented. The adjustable gaps between two planar surfaces are in the order of magnitude of 1 μm. In a first step the slip length for the system steel-oil –steel is investigated at three different temperatures: 18°C, 22°C and 25°C. The measured slip lengths are in the order of magnitude of ~100 nm.
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Characterization of Slip Activity in the Presence of Slip Bands Using Surface-Based Microscopy TechniquesSperry, Ryan Aaron 27 October 2020 (has links)
Further understanding of mesoscale slip mechanics is crucial to future development of polycrystalline metals with improved performance. The research contained within this thesis aims to characterize localized mesoscale slip on slip bands further through two studies. First, a comprehensive comparison of slip system identification techniques was carried out to further validate each method as well as compare advantages and disadvantages of each. Second, slip bands in the presence of grain boundaries were studied to better characterize the dislocation content and behavior. In the first study, the use of SEM-DIC, AFM, ECCI, and HR-EBSD to characterize slip-system activity was assessed on the same material volume of Ti-7Al. This study presents a robust comparison of the various methods for the first time, including an assessment of their advantages and disadvantages, and how they can be used effectively in a complementary manner. The analysis of the different approaches was carried out in a blind manner independently at three different universities. A Ti-7Al specimen was deformed in uniaxial tension to approximately 3% axial strain, and the active slip systems were independently identified using (i) trace analysis; (ii) in-SEM digital image correlation, (iii) observations of residual dislocations from ECCI, and (iv) long-range rotation gradients through HR-EBSD, with consistent trace identification in all cases. Displacement data from AFM was used to augment the SEM-DIC displacement data by providing complementary out of plane displacement information. Furthermore, short-range dislocation gradients (measured by DIC) provided insight into the residual geometrically necessary dislocation (GND) content, and was consistent with the GND content extracted from EBSD data and ECCI images, confirming the presence of residual GNDs on the dominant slip systems resulting in visible slip bands. These approaches can be used in tandem to provide multi-modal information on slip band identification, strain and orientation gradients, out-of-plane displacements, and the presence of GNDs and SSDs, all of which can be used to inform and validate the development of dislocation-based crystal plasticity and strain gradient models. In the second study, shear strain profiles along slip bands in a modified Rolls-Royce nickel superalloy (RR1000) were analyzed for a tensile sample deformed by 2%. The strain increased with distance away from a grain boundary (GB), with maximum shear strain towards the center of the grain, indicating that dislocation nucleation generally occurred in the grain interior. The strain gradients in the neighborhood of the GBs were quantified and generally correlated with rotation about the active slip system line direction. This leads to an ability to determine the active slip system in these regions. The dislocation spacing and pileup stresses were inferred. The dislocation spacing closely follows an Eshelby analytical solution for a single ended pileup of dislocations under an applied stress. The distribution of pileup stress values for GBs of a given misorientation angle follows a log-normal distribution, with no correlation between the pileup stress and the GB misorientation angle. Furthermore, there is no observed correlation between various transmissivity factors and slip band pileup stress. Hence it appears that the obstacle strength of any of the observed GBs is adequate to facilitate the dislocation pileups present in the slip bands. However, slip band transmission does correlate with transmissivity factors, with the current study focusing on the Luster and Morris m'-factor. Observation of strain profiles of transmitted bands indicate dislocation nucleation locations.
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Localizing interseismic deformation around locked strike-slip faultsZhu, Yijie 28 August 2020 (has links)
Localized geodetic deformation of an approximately arctangent shape around locked strike-slip faults is widely reported, but there are also important exceptions showing distributed interseismic deformation. Understanding the controlling mechanism is important to the interpretation of geodetic observations for hazard assessment and geodynamic analysis. In this thesis, I use simple finite element models to separately study the two major contributors to the deformation: far-field loading and previous earthquakes. The models feature a vertical strike-slip fault in an elastic layer overlying a viscoelastic substrate of Maxwell or Burgers rheology, with or without weaknesses representing extensions of the fault either along strike or to greater depth. If the locked fault is loaded only from the far field without the effects of previous earthquakes, localized deformation occurs only if local mechanical weaknesses below the fault and/or somewhere along strike are introduced. I first show that the effects of far-field loading are rather limited even in the presence of extreme weaknesses. Then I use idealized earthquake cycle models to investigate the effects of past seismic events in a viscoelastic Earth. I demonstrate that, after a phase of fast postseismic deformation just after the earthquake, the localization of interseismic deformation is controlled mainly by the recurrence interval of past earthquakes. Given viscosity, shorter recurrence leads to greater interseismic localization, regardless of the rheological model used. The presence of a low-viscosity deep fault zone does not change this conclusion, although it tends to lessen localization by promoting faster postseismic stress relaxation. Distributed interseismic deformation, although less reported in the literature, is a natural consequence of very long recurrence and in theory should be as common as localized deformation. The apparent propensity of the latter is likely associated with the much greater quantity and better quality of geodetic observations from higher-rate and shorter-recurrence faults. Using viscoelastic earthquake-cycle models, I also explore the role of nearby earthquakes and creeping segments along the same fault. For faults of relatively short recurrence, frequent ruptures of nearby segments, modelled using a migrating rupture sequence with or without temporal clustering, further enhance localization. For faults of very long recurrence, faster near-fault deformation induced by a recent earthquake may give a false impression of localized interseismic deformation. / Graduate
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Transients and Coil Displacement in Accelerator MagnetsWallin, Marcus January 2019 (has links)
For a long time voltage spikes has been seen in measurement data from accelerator magnets during current ramps. These has been believed to be caused by movements, but has never before been studied in depth. The purpose of this thesis is therefore to prove, or disprove, that these events are caused by movements and to analyse what kind of displacements that actually occur. Measurement data from coil voltage, magnetic pick-up coils and current during transients has been acquired and analysed for the Nb3Sn-dipole magnets FRESCA2 and 11T models—named MBHSP107 and MBHSP109. The measurement data is compared to movement simulations that was done with the ROXIE-program, which is used to calculate mutual inductance change for a number of different movement types. The study strongly suggests that the transients are caused by movements, and also indicates that the maximal length of a single slip-stick motion can be up to around 10 micrometers, mostly in the direction of the magnet’s internal forces. The study has proven that transients in measurement data occur due to coil movements, and that these can be quantified—a discovery that can possibly affect future construction and design of accelerator magnets.
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Vibracije izazvane ljudskim delovanjem kod spregnutih međuspratnih konstrukcija tipa drvo-laki beton / Vibrations of composite wood-lightweight concrete floor structures caused by human actionKozarić Ljiljana 21 September 2016 (has links)
<p>U ovom radu ispitano je dinamičko ponašanje spregnutih međuspratnih konstrukcija tipa drvo-laki beton usled svakodnevnih ljudskih aktivnosti. Pri sanaciji, nadogradnji i seizmičkom ojačanju objekata na postojeće drvene međuspratne konstrukcije najčešće se izlivaju betonske ploče koje se sprežu sa postojećom konstrukcijom. Beton u gornjoj ploči<br />međuspratne konstrukcije povećava njenu krutost i time smanjuje setljivost na dinamičku pobudu. Potreba da se smanji dodatno opterećenje na postojeće temelje konstrukcije, dovodi do sve češće upotrebe lakog betona pri sanaciji i rekonstrukciji objekata. NJegovom primenom povoljni efekti sprezanja ostaju očuvani, a prednosti u vidu smanjenja dodatne težine dolaze do izražaja.<br />Međutim, u dostupnoj literaturi, podataka o dinamičkom ponašanju spregnutih međuspratnih konstrukcija izvedenih sa lakim betonima malih zapreminskih masa nema, pa je cilj ovog rada bio da se ispitaju osnovne dinamičke karakteristike drvenih međuspratnih konstrukcija saniranih lakim betonom raznih zapreminskih težina. Analizirano je dinamičko<br />ponašanje, odnosno sračunate su prve tri sopstvene frekvencije oscilovanja četiri međuspratne spregnute konstrukcije sa identičnim poprečnim presecima i spojnim sredstvima, ali sa različitom klasom zapreminske mase lakog betona u gornjoj betonskoj ploči. Preliminarnim laboratorijskim ispitivanjem relevantnih svojstava četiri vrste lakog<br />betona, monolitnog drveta i spojnih sredstava, koja su se koristila pri sprezanju drveta i lakog betona, dobijeni su potrebni ulazni podaci za numerička istraživanja. Za potrebe analitičkog istraživanja predložena je jednostavna metoda dinamičkog proračuna sopstvenih frekvencija oscilovanja elastično spregnutih konstrukcija. Tačnost rezultata predloženog dinamičkog proračuna potvđena je eksperimentalno, i poređenjem<br />sa rezultatima programskog paketa Ansys.</p> / <p>This work has examines dynamic behavior of composite wood-lightweight concrete floor structures exposed to normal everyday human activities. In a case of restoration, renovation or seismic reinforcement, the most common approach is to pour concrete slabs onto existing wooden floor structures. Concrete in the upper zone of floor structure is increasing its stiffness and thus reducing the dynamic excitation. In the attempt to reduce the weight on the existing foundations, lightweight concrete is used for restoration and renovation. Coupling effect remains undisturbed but added weight is significantly reduced when lightweight concrete is used.<br />However, the available literature does not provide data about dynamic behavior of the composite wood-lightweight concrete floor structures; therefore the goal of this research work is to examine the characteristics of the restored wooden structures coupled with lightweight concrete of the different specific weights. This research work analyzes dynamic behavior that included first three frequencies of four composite floor structures with identical cross sections and connections, but different specific weights of the lightweight concrete in the upper layer of the concrete slab. Preliminary laboratory testing of four different types of the lightweight concrete, wood and connections, yielded necessary data for the further numeric analysis.<br />Simple calculation method for obtaining mode frequencies of the partial composite structures has been proposed, for the purpose of this analytical research. The accuracy of the proposed dynamic model has been confirmed through experimental research and compared up against the results from the Ansys</p>
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Generalized slip-flow theory and its related Knudsen-layer analysis / 一般すべり流理論とKnudsen層解析Hattori, Masanari 23 March 2016 (has links)
The content of Chapter 1 is an author produced version of a paper published in Physics of Fluids. The final publication is available at AIP via http://dx.doi.org/10.1063/1.3691262. The content of Chapters 2 and 4 is an author produced version of papers published in Journal of Statistical Physics. The final publications are available at Springer via http://dx.doi.org/10.1007/s10955-012-0512-z and http://dx.doi.org/10.1007/s10955-015-1364-0, respectively. / 京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19682号 / 工博第4137号 / 新制||工||1638(附属図書館) / 32718 / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 青木 一生, 教授 髙田 滋, 教授 稲室 隆二 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
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Structural Behavior of Reinforced Concrete Elements and Subassemblies under Fire Conditions / 鉄筋コンクリート部材および部分架構の火災時構造挙動Mohammad, Mahdi Raouffard 26 March 2018 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21066号 / 工博第4430号 / 新制||工||1688(附属図書館) / 京都大学大学院工学研究科建築学専攻 / (主査)教授 西山 峰広, 教授 原田 和典, 教授 河野 広隆 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
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Experimental Research on Rate- and State- Dependent Friction Constitutive Law Focusing on the Transient Change of Frictional Strength at Intermediate to High Slip Velocities / 中-高速度域条件下における摩擦強度の過渡的変化に着目した速度状態依存摩擦構成則に関する実験的研究Nakano, Ryuji 26 March 2018 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20924号 / 理博第4376号 / 新制||理||1628(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)教授 田上 高広, 教授 山路 敦, 教授 平原 和朗 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
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