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Dissertations / Theses on the topic 'Eccentric mechanism'
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1
Mlčoch, Pavel. "Čtyřválcový zážehový motor s excentrickým klikovým mechanismem pro osobní vozidla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232114.
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This Diploma Thesis is aimed at exploring the potential of offset crankshaft mechanism for four cylinder inline petrol engine in terms of reducing the frictional losses of the piston group. Thesis deals with the influence of eccentricity on kinematics, dynamics and balance of the crank train. Furthermore, specific crankshaft balancing is elaborated and applied on 3D CAD model of the crankshaft. Calculation of fatigue safety factor using the advanced LSA method that takes into consideration the effect of forced torsional vibration and utilizes outputs from the FEA software (ANSYS APDL) is performed as well. Thesis also includes design of two options of rubber torsion damper mounted on the engine belt pulley and the follow-up choosing of the more advisable one.
2
Freisleben, Pavel. "Dvouválcový zážehový motor s excentrickým klikovým mechanismem pro osobní vozidla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232115.
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This thesis deals with forces of the crank mechanism. The aim of this work is to find the right value of the eccentricity of the crank mechanism, which will have a positive effect on the size and course of forces that cause friction losses in the crank mechanism. Next solves this balancing eccentric unit. The last part deals with the design and strength check of the crankshaft considering torsional vibration.
3
Faiman, Jiří. "Tříválcový zážehový motor s excentrickým klikovým mechanismem pro osobní vozidla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231763.
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The first part of this thesis deals with the examination of the eccentricity of the crank mechanism for individual variables kinematics and dynamics of crank mechanism, analyticaly computed in Matlab. Then it compares the different possibilities of balancing moments of inertia forces and propose a specific design chosen for the value of eccentricity. In the second part is designed a model of crankshaft mechanism based on the investigated parameters. These parameters were carried out by structural analysis in Ansys.
4
Guo, Shixian. "Kinematic Simulation and Structure Analysis of a Morphing Flap." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8437.
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This thesis presents a study on the design and analysis of a morphing flap
structure integrated with actuation mechanism for potential application to large
aircraft. Unlike the conventional rigid flap mounted on the wing trailing edge,
the morphing flap is designed as a unitized structural system integrated with
three primary components: the upper and lower flexible skins reinforced by
stringers, an eccentric beam actuation mechanism (EBAM) with discs fixed on it,
and the connection of the discs with the stringers. Based on the EBAM concept
proposed by Dr Guo in previous research [1], the current study has been
focused on the EBAM design and optimization, kinematic simulation and
structural modelling of the morphing flap.
Although a lot of efforts have been made to develop the morphing flap in
previous research, it is lack of detailed design of the disc-skin linkage and clear
view on the mechanism optimization in relation to the shape requirement. The
main objective of this research is to meet the morphing shape requirements and
calculate the actuation torque for a specified morphing flap. Firstly effort was
made to design and optimize the disc shape and locations in the EBAM for the
best matching of the specified morphing shape with minimum actuation torque
demand. It is found that minimum three discs are required and their locations
have little effect on the actuation torque. Secondly attention was focused on
designs of the disc and a C-linkage with the stringers. To ensure that the C-
linkage works in practice, a twisted stringer flange design was proposed. Thirdly
the actuation mechanism was integrated with the stiffened skin to play the role
of an active rib in the flap structure. Based on the design, FE modelling and
analysis of the morphing flap structure was carried out. The behaviour of the
morphing flap under the internal actuation and external aerodynamic load was
applied for stress analysis and detailed design of the structures. Finally the
kinematics of the integrated morphing flap was simulated by using CATIA to
demonstrate the feasibility and the effectiveness of the improved design.
5
Süttő, Daniel. "Pětiválcový řadový vznětový motor s excentrickým klikovým mechanismem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231456.
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The aim of this thesis is to find out the influence of eccentricity of crank mechanism on the duration of the force between the piston and the cylinder liner. At the same time I wanted to find out its influence on the balance of the whole system. It is important to design the balance for the selected value of the eccentricity and subsequently put through the crank shaft to stress analysis with torsional vibrations. I got so interested in this problem that in addition to the whole topic I designed a torsional vibration damper.
6
Tais, Senna. "Transfer Mechanisms of Eccentric Training : The effects of EMG-biofeedback in training." Thesis, Gymnastik- och idrottshögskolan, GIH, Institutionen för idrotts- och hälsovetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:gih:diva-2303.
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Abstract Aim: The aim of this study was to investigate how neural mechanisms operate during maximum strength training in the Quadriceps Femoris muscle group. One of the main objectives is to investigate the effects of five weeks unilateral maximum eccentric strength training on contralateral neural adaptations. The second is to investigate the effects of adding electromyographic (EMG) biofeedback into the training intervention. Method: 20 healthy, recreationally active men and women had to undergo five weeks (three training sessions per week, resulting in 15 sessions in total) of maximum isokinetic unilateral eccentric strength training of the Quadriceps femoris muscle, with EMG biofeedback; FBG, n=10 five women and five men, or without EMG biofeedback; RTG n=10 five women and five men. The study was performed at the Laboratory of Biomechanics and Motor control, BMC Laboratory, Stockholm Sweden. Results: The results demonstrated an increase in concentric strength development in the trained leg; before 130 ± 43 Nm and after training 148 ± 46 Nm, (p=0.006). No significant increase in strength was detected for the untrained leg. Further, post hoc tests showed a tendency towards an increase in level of activation (LOA) of the trained leg in the FBG; from 69 ± 15 % before to 81 ± 13 % after training (p=0.097). No significant differences in the ecc:con EMG-ratio or in antagonist co-activation after the training intervention were shown. Conclusion: No significant difference in strength development was shown, whether training occurred with or without EMG biofeedback. However, eccentric training tended to induce transfer of neural activation to a maximum voluntary contraction (MVC) in the trained leg only in the group training with EMG biofeedback. In addition, the results revealed that eccentric strength training improved concentric strength in the trained leg but induced no transfer to the contralateral untrained leg. The benefits and prospects with incorporating feedback into training remains somewhat unknown and requires further research to obtain deeper understanding of the neural mechanisms affected by biofeedback.
7
Franchi, Martino V. "Mechanisms of human skeletal muscle remodeling in response to concentric and eccentric loading paradigms." Thesis, Manchester Metropolitan University, 2014. http://e-space.mmu.ac.uk/326244/.
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It is common knowledge that resistance exercise promotes muscle growth (hypertrophy) and increased strength and function: thus, regular exercise can help minimize the loss of muscle mass and function in healthy ageing. Skeletal muscle can contract by either shortening or lengthening (concentrically or eccentrically, respectively). A substantial number of studies focused on the effect of concentric versus eccentric training protocols on muscle morphological and functional changes: eccentric contractions are generally thought to result in more increased muscle hypertrophy and strength, because of the higher force produced by the muscle and the more severe exercise induced muscle damage, which may lead to a stronger adaptations in muscle remodeling and repair processes. Study 1 shows that ECC and CON exercise protocols lead instead to similar gains in muscle size, but through different architectural remodeling mechanisms: moreover, acute contraction-specific molecular responses have been characterised. Study 2 and Study 3 were then performed in order to gain novel insights into the relationship between these morphological adaptations and the metabolic responses (MPS, muscle protein synthesis) of human skeletal muscle in response to chronic ECC vs. CON loading paradigms. Study 2 was first carried out in order to validate the use of deuterium oxide isotope tracing technique for measuring changes in MPS in free-living subjects over longerterm periods (compared to normal AA infusion studies) of resistance exercise. After assessing the feasibility of deuterium oxide tracing technique in measuring MPS response during resitance-training protocols, study 3 investigated the chronic responses in MPS to ECC vs. CON loading in two 3 different sites of the human vastus lateralis, presenting novel insights into MPS and skeletal muscle homogeneity, attempting to link MPS changes to the different mechanisms of muscle morphological remodelling occurring after ECC vs. CON training.
8
Faramaz, V., S. Ertel, M. Booth, J. Cuadra, and C. Simmonds. "Inner mean-motion resonances with eccentric planets: a possible origin for exozodiacal dust clouds." OXFORD UNIV PRESS, 2017. http://hdl.handle.net/10150/623054.
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High levels of dust have been detected in the immediate vicinity of many stars, both young and old. A promising scenario to explain the presence of this short-lived dust is that these analogues to the zodiacal cloud (or exozodis) are refilled in situ through cometary activity and sublimation. As the reservoir of comets is not expected to be replenished, the presence of these exozodis in old systems has yet to be adequately explained. It was recently suggested that mean-motion resonances with exterior planets on moderately eccentric (e(p) greater than or similar to 0.1) orbits could scatter planetesimals on to cometary orbits with delays of the order of several 100 Myr. Theoretically, this mechanism is also expected to sustain continuous production of active comets once it has started, potentially over Gyr time-scales. We aim here to investigate the ability of this mechanism to generate scattering on to cometary orbits compatible with the production of an exozodi on long time-scales. We combine analytical predictions and complementary numerical N-body simulations to study its characteristics. We show, using order of magnitude estimates, that via this mechanism, low-mass discs comparable to the Kuiper belt could sustain comet scattering at rates compatible with the presence of the exozodis which are detected around Solar-type stars, and on Gyr time-scales. We also find that the levels of dust detected around Vega could be sustained via our proposed mechanism if an eccentric Jupiter-like planet were present exterior to the system's cold debris disc.
9
Jakel, Roland. "Analysis of Bolted Connections in Creo Simulate - Theory, Software Functionality and Application Examples." Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-114533.
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Die Präsentation stellt kurz die Grundlagen der Berechnung von Schraubenverbindungen in Anlehnung an die VDI-Richtlinie 2230 Teil 1 dar. Auch die vier FEM-Modellklassen, die die VDI 2230 Teil 2 (Entwurf) zur Berechnung von Mehrschraubenverbindungen vorschlägt, werden behandelt, und die in Creo Simulate vorhandenen Softwarefeatures zu deren Umsetzung vorgestellt. Es folgt eine Darstellung, was bei der Linearisierung von Schraubenverbindungen zur vereinfachten Berechnung zu beachten ist, und wieso bei der Berechnung im FEM-System dann nicht notwendigerweise eine Vorspannung benötigt wird. Ausführlich wird das neue Schraubenfeature in Creo Simulate betrachtet, das eine weitgehend automatisierte Modellierung und Berechnung von Standardverschraubungen erlaubt. Weitere Features, wie die neuen Vorspannelemente, werden erläutert, sowie auch die Grenzen der Software aufgezeigt. Abschließend werden zwei anspruchsvolle Anwendungsbeispiele vorgestellt: Eine zentrisch belastete Verschraubung mit Berücksichtigung von Elasto-Plastizität und einer komplexen Lasthistorie (Anziehen durch Anzugsmoment, Setzeffekte, Entfall des Torsionsmomentes durch das Anziehen, Betriebskraft) sowie eine exzentrisch belastete Verschraubung, die wegen eines relativ dünnen Flansches starke Biegezusatzbeanspruchungen erfährtThe presentation shows the foundations of bolt analysis according to VDI-guideline 2230 part 1. In addition, the four FEM model classes proposed in VDI 2230 part 2 (draft) are described, as well as the features available in Creo Simulate to realize these model classes. Next, the presentation shows the requirements for linearizing bolted connections, and why in a FEM analysis with a linearized connection no preload is necessary. The new fastener feature introduced in Creo Simulate is explained in detail. This feature allows the automated modeling and analysis of bolted connections having standard geometry. Further software features, like pretension elements, as well as the current software limitations are shown. Finally, two advanced application examples are shown: A centrically loaded bolted connection taking into account elasto-plasticity and a complex load history (tightening torque, embedding, removal of tightening stress, operational load), and an eccentrically loaded flange connection, which is subjected to high additional bending loads because the flange is relatively thin
10
TAN, CHUAN-MING, and 譚傳明. "Muscle mechanism analysis in concentric and eccentric contractions." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/67672748990661547136.
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11
Ye, Cian-Jhih, and 葉千芷. "Analysis of Compound Bow with Eccentric Pulley Lift Mechanism." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/48949791893404752907.
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碩士崑山科技大學
機械工程研究所
102
Archery is popular in the world. Usually recurve bow and traditional bow are used in Archery. Additionally, compound bow with better performance are gradually popularized. The particularity of compound bow is a let-off device, i.e. an eccentric pulley device. The device provides a force gap to generate a force saving effect in the period of Pulled up to the full bow. The study investigated the design method of an existed compound bow with two symmetrical eccentric pulleys. The elements of the compound bow are drawn and established as models. The tension forces are measured by a force steelyard in Pulling up to full bow and expressed as a force diagram. The diagram is helpful to analyze the design theory of let-off device.
12
Chen, Tsung-Hsien, and 陳宗賢. "Mechanical Behavior of Instant Landslide Using Infinitesimal Eccentric Rotation Damping Mechanism." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/86203892612540031958.
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碩士國立嘉義大學
土木與水資源工程學系研究所
98
Slope disasters were caused by the debris of slope continuing to move downhill under the influence of gravity. Taiwan locates on the Pacific seismic zone, and is threatened by earthquakes, typhoons and heavy rain and other extreme weather. Thus, threat of slope disasters is on the crease. On April 2010, Chidu section case of National Highway No. 3 without any warning, a large-scale instant slope landslide occurred. Once, that instant landslide shocked the engineers. In this study, the slope landsides were categorized into two major kinds. One is the infrastructures of slope stability instantly totally lost its ability for supporting landside called instant landslide; the other is those facilities of slope stability progressively lost the bearing capacity of the landside called progressive landside. The two kinds of landslides were researched by experiments of model and numerical simulation for clarifying the mechanical behavior of the instant landslide. Landslides on slope were dynamical behavior of non-continuum and large displacement. Usually, it is effective to use the circular particle model of Distinct Element Method (DEM) for simulate the slope disasters. In fact, the contact between circular particles is face contact, so particles possess the abilities of moment translation and dissipation of rotational energy. It is equitant that the particles have the rotational spring and rotational damping effect in mechanical mechanism. However, as traditional viscous damping and local damping mechanisms, the former computation is not efficient, and the latter is merely suitable for quasi-static simulation. In this study, the mass center of circular particle is slightly adjusted to eccentricity to appear the effectiveness of rotational spring, and using viscous damping joins local rotational damping dissipating energy in the rotational direction only, this mechanism is called Infinitesimal Eccentric Rotation Damping (IERD) mechanism. IERD is used to simulate experiments of the instant landside model, the results is quite satisfactory on a small scale model test on the instant landslide. Finally, the result of simulation and experimental is similar to the experiment of the simplified model of high way slope instant landside. The conclusions effectively confirmed the applicability of this IERD mechanism for the circular model of Distinct Element Method and simulation of slope disaster.
13
Lin, Yu Cheng, and 林煜晟. "The Design of Conjugate Translating Cam Mechanisms with Translating Follower Having an Eccentric Roller." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/07362720339560101070.
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碩士國立清華大學
動力機械工程學系
104
Generally the disk cam mechanism needs to equip with a return spring to maintain the contact between the cam and the follower. However, a larger space is required to accommodate the return spring, and the force exerted by the spring may result in a larger contact stress. To avoid the aforementioned disadvantages, the conjugate cam mechanism can be employed instead. The clearance between the conjugate cam and its roller follower can be controlled by means of accurately machined cam profiles and an adequate lubrication at the contact surface. Nevertheless, the accurate cam profile is costly to fabricate. Alternatively, by the application of the adjustable eccentric roller, the clearance can be eliminated efficiently and economically. But when cam works, the contact stress will also create the clearance .Hence, it is the aim of this research to show in ideal situation how to adjust the eccentricity of the eccentric roller to eliminate the clearance caused by contact stress. Firstly, the ideal profiles of the conjugate cams were analytically synthesized by employing the concept of velocity instant centers. Then, the accompanying cam profiles were calculated with considering the adjusted design dimensions caused by the eccentricity of the eccentric roller. The profile differences between the ideal cam and the accompanying cam were regarded as the expected amount of preloading. Next, the force analysis and the contact stress analysis of the conjugate cam mechanism were performed for allocating the suggested range of adjustment of eccentric roller and the conjugate cam arrangement. The obtained results indicated that the conjugate cam mechanism with an adjustable eccentric roller was effective in eliminating the clearance.When the eccentric roller had 0.25 mm eccentricity , the center orientation of the adjustable eccentric roller was suggested to be between 5 and 15 degrees. Meanwhile, the areas of two conjugate cams should be nearly the same so as to avoid undesired vibrations due to non-uniform mass distribution. The arrangement and the roller adjustment of the conjugate cam mechanism presented in this research may be helpful to achieve its expected purpose easily and directly.
14
Lopez, Miquel. "Stiffness and grip force measurement using an eccentric mass motor: a dynamic model and experimental verification." Phd thesis, 2012. http://tel.archives-ouvertes.fr/tel-00807081.
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Loading can dramatically reduce the vibratory displacement and the operating frequency in vibrotactile systems implementations that use an eccentric mass motor, but this phenomenon is not well modeled or understood. In this work, we derive a dynamic model of this phenomenon and implement a system for measuring stiffness and grip force that take advantage of this phenomenon. The system is based on a non-interposed sensing approach using an eccentric mass dc motor mounted on the outside of the index finger. If the device were to be worn as a wearable sensor, it could be embedded in a ring. The basic idea is that a person could wear the ring sensor and through it measure the stiffness and grip force when squeezing various objects, without requiring the ring sensor to actually contact the object. The results show that grip force and muscle stiffness vary with motor velocity (operating frequency) and thus that the measurement of velocity can be used to infer grip force and stiffness. With the validated model, we also developed an optimization routine which computes the best design parameters for inertial load and voltage to maximize the phenomenon. This provided insight into the optimal parameters that should be used in an actual ring sensor design to achieve high performance by attaining a good trade-off between high sensor sensitivity and low level of vibration.
15
Wu, Yi Chen, and 吳苡甄. "Effects of concentric and eccentric cycling exercise on platelets mitochondrial function and left ventricular mechanics in sedentary young men." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/s62666.
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碩士長庚大學
物理治療學系
105
Background: According to the World Health Organization, ischemic heart disease (IHD) is the leading cause of death in the world. Myocardial ischemia might cause myocardial damage and dysfunction, leading to higher systolic dyssynchrony index (SDI). Hypoxia-induced thrombin generation and coronary stenosis are risk factors of IDH. Platelets are important in the development of thrombotic events on IHD. Mitochondria regulated platelets function and activation, which were associated with thrombin generation. According to several researches, exercise could not only improve cardio fitness but also mitochondria function. However, most results of the past researches were about concentric exercise. Eccentric training can produce high force yet demand low metabolic cost, avoiding some discomfort under hypoxic condition or high intensity exercise, such as chest pain and short of breath. Chronic eccentric training may be the rehabilitation countermeasure with the potential to overcome the deficits of cardiopulmonary limitation. The purpose of this study is using hypoxia as the pathological condition to compare the effects between concentric cycling exercise (CCE) and eccentric cycling exercise (ECC) regimens on platelets mitochondrial capacity and left ventricular function. Method: Thirty four sedentary men were randomized to CCE group (n=17) and ECC group (n=17). The training program consisted in CCE or EEC for 40 minutes/day, 5 days/week for 6 weeks. The measurements included platelets mitochondrial OXPHOS capacity, left ventricular function and muscle strength of lower limbs which are analyzed by high resolution respirometer (Oxygraph-2k), 3D echocardiography and isokinetic dynamometer respectively. Result: Comparing with normoxia and hypoxia in platelets mitochondrial function, there are less OXPHOS and ETS capacities in hypoxia. Comparing with normoxia and hypoxia in left ventricular mechanics, there are less EDV, ESV, SV and higher HR, SDI (Vel.), SDI (Vol.) in hypoxia. Both ECE and CCE groups had improvement in isokinetic dynamometer. Besides, ECE have more improvement in muscle strength and torque. Conclusion: ECE can improve muscle strength, muscle torque and neural adaptions without stressing on cardiopulmonary system. By performing ECE on patients with limited cardiovascular exercise tolerance such as elders or chronic health conditions can produce high force but using lower metabolic cost.
16
(8099576), Sang Kyu Kim. "Transient Dynamics of Compound Drops in Shear and Pressure Driven Flow." Thesis, 2019.
Find full textAbstract:
Multiphase flows abound in nature and enterprises. Our daily interactions with fluids - washing, drinking, and cooking, for example - occur at a free surface and within the realm of multiphase flows. The applications of multiphase flows within the context of emulsions, which are caused by mixing two immiscible fluids, have been of interest since the nineteenth century: compartmentalizing one fluid in another is particularly of interest in applications in pharmaceutical, materials, microfluidics, chemical, and biological engineering. Even more control in compartmentalization and delivery can be obtained through the usage of double emulsions, which are emulsions of smaller drops (i.e., inner drop) within larger drops (i.e., outer drop). The goal of this work is to understand the dynamic behavior of compound drops in confined flow at low Reynolds numbers. These behaviors include the migration patterns, limit cycles, and equilibrium locations in confined flows such as channel flows.Firstly, we look at non-concentric compound drops that are subject to simple shear flows. The eccentricity in the inner drop is either within the place of shear, normal to the plane of shear, or mixed. We show unreported motions that persist throughout time regardless of the initial eccentricity, given that the deformations of the inner and outer drops are small. Understanding the temporal dynamics of compound drops within the simple shear flow, one of the simplest background flows that may be imposed, allows us to probe at the dynamics of more complicated background flows.
Secondly, we look at the lateral migration of compound drops in a Poiseuille flow. Depending on the initial condition, we show that there are multiple equilibria. We also show that the majority of initial configurations results in the compound drop with symmetry about the short wall direction. We then show the time it takes for the interfaces to merge if a given initial configuration does not reach the aforementioned symmetry.
Thirdly, while the different equilibria of compound drops offer some positional differences at different radii ratio, we show that the lift force profiles at non-equilibrium locations offer distinctly different results for compound drops with different radii ratio. We then look at how this effect is greater than changes that arise due to viscosity ratio changes, and offer insights on what may create such a change in the lift force profile.