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1
Šimčík, Jaroslav. "Konstrukce hydraulické štípačky dřeva." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229211.
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Bc. Jaroslav Simcik Construction of hydraulic wood-splitting machine DP, Institute of production machines, systems and robotics, 2010, p. 60, fig. 30, appendices 7, This master ´s thesis is concerned with the wood-processing technology with a focus on the construction of hydraulic wood splitter machine with a force 120 kN.
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Kontz, Matthew. "Haptic enhancement of operator capabilities in hydraulic equipment." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/15862.
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Sepehri, Nariman. "Dynamic simulation and control of teleoperated heavy-duty hydraulic manipulators." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30846.
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Some relevant aspects of dynamics and control of heavy-duty hydraulic machines in a teleoperated mode were investigated. These machines, such as excavators and forest
harvesters, are mostly used in primary industries. They have a manipulator-like structure with a nonlinear and coupled actuating system. The aim of the project is to investigate different approaches towards converting such machines, with minimum changes, into task-oriented human-supervisory control systems. This provides the opportunity
to use both human supervision and robotic power in hazardous environments and for tasks for which human decision is necessary.
A methodology was developed for fast and accurate simulations. Analytical, steady-state and numerical techniques were combined using Large-Scale Systems analysis. The inclusion of nonlinearities in the form of discontinuities (e.g., gear backlash and stick-slip friction) in the model was investigated. Numerical simplifications of the structural dynamics and alternative solutions for the hydraulic part were also studied.
The model describing the performance of the machine has been written in ACSL (Advanced Continuous Simulation Language) on a VAX computer system. A modified version of the program is at present running close to real-time on a single processor in conjunction with high speed graphics in a manner similar to a flight simulator used for human interface studies and training.
The model also evaluates the performance of the machine in a teleoperated mode and under different control strategies. As a result a velocity control algorithm has been developed which is applied in conjunction with the closed-loop components for teleoperation of heavy-duty hydraulic machines; it is basically a feedforward compensation
which uses the measured hydraulic line pressures along with fluid-flow equations as criteria
to control the joint velocities as well as to uncouple the interconnected actuating system. The control algorithm has been written in C language and is running on an IRONICS computer system, interfaced between the human operator and the machine. The simulation results are supported by the experimental evidence. The experiments were performed on a Caterpillar 215B excavator.
Improved operator safety, extension of human capability, job quality and productivity
increase are the advantages of a successful implementation of robotic technology to these industrial machines.<br>Applied Science, Faculty of<br>Mechanical Engineering, Department of<br>Graduate
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Ipek, Levent. "Optimization Of Backhoe-loader Mechanisms." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607722/index.pdf.
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This study aims to develop a computer program to optimize the performance of loader mechanisms in backhoe-loaders. The complexity and the constraints imposed on the loader mechanism does not permit the use of classical optimization techniques used in the synthesis of mechanisms. Genetic algorithm is used to determine the values of the design parameters of the mechanism while satisfying the constraints and trying to maximize breakout forces that the machine can generate.
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Petit, Giai. "Analysis on the tapering of Xylem conduits as a compensation mechanism for hydraulic limitations to tree growth." Doctoral thesis, Università degli studi di Padova, 2008. http://hdl.handle.net/11577/3425105.
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In trees, water flows throughout a network of xylem conduits by mean of a negative pressure gradient between sites of consumption (leaves) and absorption (roots), the distance of which can be longer than 120 m in the world's tallest specimens. The architecture of the transport system must guarantee an adequate water supply and the mechanical stability of the tree. In fact, increased hydraulic constraints cause strong limitations to height growth. Trees adopt a number of structural modifications to compensate for the effect of these constraints and the tapering of xylem conduits is probably the most effective. Recent studies seemed to support the WBE model's hypothesis about the universality of the degree of conduit tapering in vascular plants, which should converge to a threshold value that minimizes the effect of path length on the total hydraulic resistance, which hence would remain substantially constant with increasing tree height. Therefore, it has been hypothesized that hydraulic constraints, which lead to the decline in the rate of height growth, are consequent to a reduced degree of conduit tapering, whereas the maximum height is substantially set by the absolute dimensions of xylem conduits, in particular those at the apex, where the most hydraulic resistance is concentrated.
The aim of this work was to evaluate the combined effect of the dimension of xylem conduits and their tapering in compensating the inhibition-action of hydraulic constraints on height growth. Among the discussed topics, the first is a thorough analysis of the mathematical and logical structure of the WBE model, while the others describe empirical experiments. The first consists of an analysis of the structural modifications of the xylem transport system during ontogenesis in A. pseudoplatanus. Specimens from two age/size classes (young/small and old/tall) were selected and the use of grafted plants (i.e., clones of the parent plants selected in the field) as controls allowed to decouple the auto-correlation between age and dimensions, and thus to determine which of these two factors is responsible for the structural modifications.
In the fourth and fifth chapter, the importance is discussed of conduit tapering in coniferous species (Pinus cembra, Larix decidua and Picea abies) at the treeline, where low temperatures inhibit the formation of wide conduits and height growth is strongly limited. In P. cembra, the analysis of conduit tapering was extended to roots, whereas on the selected specimens of P. abies a heating system was applied to the developing apical bud for two successive growing seasons.
In chapter 6, a new hypothesis is elaborated regarding the heartwood formation in A. pseudoplatanus, where the intra-ring sectoriality of water flows, tested by a dye injection into the innermost ring of 5-6 year-old, 1 m long branches, and conduit tapering might play a key role.
In all the experiments, wooden samples were extracted at different distances along the longitudinal axis of each stem/branch. Samples were embedded in paraffin, cut with a rotary microtome at 10-12 ?m and sections were stained with safranine and fixed permanently on slides. Slides were observed under the microscope, the lumen areas of conduits measured and the averaged hydraulically weighted diameter assessed for each distance.
In A. pseudoplatanus, an overall reduction in the degree of conduit tapering and an increase in width of the apical conduits of old/tall trees compared to young/small ones was not detected in the relative grafts. The degree of tapering in the small plants, irrespective of their meristematic age, resulted in agreement with the WBE model's principle of minimization and stabilization of the total hydraulic resistance. These structural modifications were therefore connected to the size variations rather than to proper ageing. Moreover, the safranine injected into the innermost ring of branches of the same species flowed until the apex, remaining confined within the innermost ring at each internode, i.e., without any radial spread between successive rings, thus demonstrating a substantial intra-ring sectoriality of water flows.
At the treeline, trees showed a degree of conduit tapering on average in agreement with the WBE model's prediction. Moreover, warming applied to the developing apical buds promoted the formation of wider apical conduits and apical shoots resulted as longer, thus supporting the hypothesis of a hydraulic limitation to height growth also in trees at the treeline.
Lastly, it was observed that the tapering of xylem conduits is not confined to the aboveground organs, but also continues along the roots, where the degree of tapering resulted as higher than that of the stem.
The analyses presented in this work demonstrates the importance of conduit tapering as a fundamental mechanism of compensation for the limiting effect of hydraulic constraints on growth in height, whose maximum seems to substantially depend on the possibility of forming wide apical conduits.
6
Hess, Jeremy. "In-Situ Testing of Uretek's Injectable Barrier as a Mechanism for Groundwater Control." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6095.
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Construction projects involving the installation or repair of subsurface structures or utilities often require dewatering to induce a temporary lowering of the local groundwater elevation to facilitate construction. In the event that a known contaminant plume is present in an adjacent area, this dewatering may inadvertently draw the contaminant into the previously uncontaminated work area. Uretek Holdings, Inc. has developed its Injectable BarrierSM to be installed prior to dewatering exercises to provide a groundwater cut-off by reducing the potential movement of groundwater due to the hydraulic gradient induced by dewatering. A benefit of Injectable BarrierSM as compared to conventional methods of hydraulic control is that excavation is not required prior to its installation and no excess soils are generated through its installation. Injectable BarrierSM is a proprietary process registered with the United States Patent and Trademark Office by Uretek Holdings, Inc.
Since methodical in-situ testing of the effectiveness of the Injectable BarrierSM has not been performed to date, it was the focus of this research to test the performance of the barrier under in-situ conditions utilizing a subsurface environment indicative of a West-Central Florida location. A testing plot to perform this research was selected on Hillsborough County property in Tampa, Florida which provided both a relatively shallow groundwater elevation in addition to a clay confining layer at a relatively shallow depth, making this an ideal location for testing the performance of the Injectable BarrierSM.
After establishing the native conditions through baseline pump testing and repeating the testing procedure following the installation of the Injectable BarrierSM, a quantification of the reduction in hydraulic conductivity was achieved. Pumping tests were performed on the Injectable BarrierSM at its standard spacing as well as modified versions of the barrier with variation in the lateral spacing to include 6 foot, 4 foot, 3 foot, and 2 foot injection patterns to determine if a modified injection process could improve its performance. The 3 foot lateral spacing corresponding to the standard Injectable BarrierSM process indicated a 20% reduction in the hydraulic conductivity following its installation. By performing a small scale excavation following the completion of all pumping tests, it was discovered that the dispersion of the material in the subsurface appeared insufficient to provide the coverage needed to establish a barrier capable of further reducing the local hydraulic conductivity, especially at the shallowest injection depth of 3 feet below land surface (ft bls). It is concluded that modified amounts of injected material, closer lateral injection spacing, and potentially modified injection temperatures and component ratios could increase the effectiveness of the Injectable BarrierSM.
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Novotný, Jan. "Zakládací zařízení do víceetážové pekárenské pece." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-416617.
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This thesis is aimed at the design of a loading device for a multi-storey bakery oven, which is going to be located in a bread production line. The introduction describes a principle of operation of the bread line and defines the parameters of the device. Furthermore, the hygienic, design and material requirements for the machines which are used in a food industry are briefly stated. Next part summarizes the possibilities of design solutions and the chosen concept. The construction part is aimed at the design of the conveyor and the scissor mechanism. In the calculation part, a static calculation of the lifting mechanism and a strength check of its arms and pins is performed. This thesis also includes the design of a hydraulic circuit for a stroke drive. Finally, the method of a control of the stacker and its safety elements are discussed.
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Ma, Xin Bo. "Characteristic analysis, regulating mechanism modeling and advanced control on hydraulic adjustable dampers for automotive semi-active suspensions." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3951593.
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Adams, Henry. "Temperature Sensitivity, Physiological Mechanism, and Implications of Drought-Induced Tree Mortality." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/228494.
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Drought-induced tree mortality is an emerging global phenomenon that appears related to climate change and rising temperatures in particular, and may be an early indication of vegetation change. However, vegetation response to climate change is uncertain, particularly for future novel climates. Notably, no current models of vegetation change attempt to mechanistically predict plant mortality, and in particular, mortality of trees, which exerts strong influences on ecological function. Resolving uncertainties surrounding the physiological mechanism and temperatures sensitivity of tree mortality is a current challenge in global change ecology. The objectives of this dissertation were to 1) consider tree mortality consequences for earth system processes related to carbon, water, and energy exchange that include climate regulation; 2) explore tree mortality effects on the water cycle by developing hypotheses and research needs; 3) quantify the temperature sensitivity of drought-induced tree mortality and gain insight into the physiological mechanism of mortality; 4) quantify the relationships among temperature, stored carbohydrate resources, and gas exchange to further elucidate physiological tree mortality mechanisms; and 5) quantify the sensitivity of two species of pine seedlings to progressively elevated temperatures and relate mortality to the effect of temperature on carbon metabolism. Major findings of this dissertation relate to the temperature sensitivity, physiological mechanism, and implications of tree mortality. Assessment of the potential consequences of tree mortality for earth system processes documented the contrasting influences of tree mortality on the terrestrial C cycle and land-surface energy exchange, the balance of which will determine the net effects on climate regulation (Appendix A). Following a survey of the ecohydrology literature, thresholds for tree mortality to cause watershed changes were hypothesized at ~20% loss of canopy cover, ~500 mm of annual precipitation, and whether flows are snowmelt dominated (Appendix B). Elevated temperature (~+4°C) accelerated tree mortality by 28% during experimental drought, a difference related to cumulative respiration dynamics in piñon pine (Appendix C). Stored carbohydrate resources were declined during lethal drought but were not entirely depleted prior to mortality (Appendix D). Seedlings exhibited progressive declines in time-to mortality with increased temperatures, a response related to C metabolism (Appendix E).
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Weerasinghe, Isuri. "Investigation of the hydraulic performance at the geosynthetic clay liner overlap." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/208258/1/Isuri_Weerasinghe_Thesis.pdf.
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Geosynthetic clay liners (GCL) are a critical barrier component in containment systems such as landfills and mines. This thesis presents a laboratory testing method and a numerical modelling technique to evaluate the hydraulic performance of Geosynthetic clay liner overlaps. The outcome of the thesis allows practitioners to evaluate specific GCL products and optimise the liner system performance based on the environmental conditions of the specific barrier applications. The industry benefits by reduced long-term experimentation and minimised financial costs, and improvement of service life of barrier systems, thereby minimising potential ground water contamination and contributing to environmental protection.
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Macejka, Andrej. "Dílenský mobilní manipulační stůl." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-416626.
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This diploma thesis is concerned with the design of lift table with hydraulic actuator system. Lift table is supposed to perform vertical motion and tilting the upper desk in horizontal axis. In background research are explored various suitable movement mechanisms and types of actuating systems. After choosing the right mechanism type for lifting and tilting, actuating system and various design components the force and strength calculations are performed analytically and by finite element analysis. The hydraulic schema, 3D model of assembly and drawings are made.
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Bennour, Ziad. "Effect of Hydraulic Fracturing Fluid Viscosity on Stimulated Reservoir Volume for Shale Gas Recovery." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225563.
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Palnati, Mahendra. "Design, Fabrication and Analysis of a Paver Machine Push Bar Mechanism." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/6007.
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Now-a-days, the major challenge that’s being faced by the concrete industry is the cleaning of concrete handling equipment. Concrete consists of aggregates, which harden with time, and the transportation of concrete mixture within the plant is a significant problem. This will not only increase the overall maintenance cost, but will lead to loss of raw materials, affect the rate of production, and reduce the lifetime of concrete handling equipment.
The present study focuses on the design and implementation of an adaptive cleaning mechanism in the concrete industry and its importance in achieving efficient cleaning, which is tested to verify its performance in the Paver production plant. The goal of this study is to provide practical evidence about the importance of adaptive cleaning mechanisms for industrial applications.
The first chapter gives a detailed introduction about pavers and the production process, the cause of material loss that occurs during transportation of wet concrete mixture inside a paver plant, and its effect on handling equipment and work environment. The second chapter explains design and working of the paver machine push bar mechanism, which can be implemented in a hydraulic press production process of pavers. The third chapter includes analysis and results of the mechanism obtained using Solidworks and Autodesk Inventor followed by observations that are achieved based on practical application of this mechanism in a paver production plant.
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Nandela, V. K. Reddy. "Clogging of drainage material in leachate collection systems." Ohio : Ohio University, 1992. http://www.ohiolink.edu/etd/view.cgi?ohiou1172864667.
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Cetin, Betul. "Design Of A Demolition Boom." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/2/12608797/index.pdf.
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ABSTRACT
DESIGN OF A DEMOLITION BOOM
Ç<br>etin, Betü<br>l
M.S, Department of Mechanical Engineering
Supervisor : Prof. Dr. Eres SÖ<br>YLEMEZ
August 2007, 96 pages
Excavators are used for many purposes. Some of these are digging, drilling, breaking
and demolition. A demolition excavator boom consists of 3-piece boom which is
different in form and construction from a 2-piece boom used in standard excavator.
The aim of this thesis is to design a demolition boom for hydraulic excavator with
operation weight of 30 ton. With this construction a higher reach is gained. Design of
the demolition boom consists of three stages. Firstly the mechanism design is
performed to determine the basic link dimensions. In the second step the structural
shape of the boom is estimated to perform static stress analysis. The EXCEL
program is chosen due to the ease of repetative calculations and applying the changes
in structure parameters. The demolition boom is modeled by PRO-ENGINEER, and
consequently the model is analyzed by using a Finite Element Analysis (FEA) in
MSC.Marc-Mentat. According to the FEA results the model is revised.
Keywords: Demolition Excavator, Mechanism Design, Structural design
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Kaše, Vladimír. "Zdvihací a manipulační zařízení pro podvěsné příslušenství letadla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230373.
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The thesis is dealing with the design proposal of mobile handling equipment for the aircrafts´ overhead accessory. In its initial part it describes different types of manipulators in use, following by several possibilities how to solve the problematics. The main part of the thesis is focused on concrete solution and construction of such manipulating facility, including the strength and control calculations.
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Slingsby, Jasper. "Branch junction constriction and hydraulic limitation in two species in the Cape Proteaceae : a mechanism explaining the trade-off between longevity and degree of ramification in the Cape Proteaceae." Bachelor's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/26047.
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The purpose of this study was to establish if hydraulic limitation and branch junction constriction explain the trade-off between longevity and increased ramification in species of the Cape Proteaceae. This was done by establishing if branch nodes are regions of greater resistance to xylem sap flow in the study species; attempting to quantify nodal resistance for a plant as a whole; and by determining if there is any evidence for hydraulic limitation or compensation in Leucadendron laureolum (Lam.) Fourc. and Leucospermum oleifolium (Berg.) R. Br. individuals. The extent of branch junction constriction was established by comparing the ratio of the xylem sap flow rates of adjacent branch segments of equal length. The ratio of a proximal intemodal to a distal intemodal segment was compared against the ratio of a proximal intemodal segment to a distal node. Branch nodes were found to create significant resistance to xylem sap flow rates in both species (p < .005 for L. laureolum, and p < .05 for L. oleifolium). Total nodal resistance in L. laureolum was modelled as equivalent extra branch length, and as loss of sap flow rate. Equivalent extra branch length increased exponentially with increased branching order, and increased much faster in more ramified plants. Loss of flow rate increased linearly with increased branching order and was unaffected by differences in ramification. This was because the nodes in more ramified plants had smaller basal sapwood areas, and the resistance imposed by nodes decreased with decreased basal sapwood area. As more ramified plants tend to branch earlier, and/or with greater temporal frequency, they will still accumulate greater nodal hydraulic resistance faster than less ramified plants, and thus may be limited to smaller size and younger maximum age. Branch specific conductivities (kₛ), leaf specific conductivities (LSC) and transpiration rates were investigated in higher (11 nodes) and lower (10 nodes) order branches of L. laureolum. All were found to be significantly lower in higher order branches (11 nodes), which can be related to greater nodal resistance to sap flow limiting the amount of water available to the area of developing xylem, causing the vessels to have narrower diameters. There was no significant difference in leaf to sapwood area ratios (Aₗ/As) between the two branching orders. Previous studies have suggested that changes in Aₗ/Aₛratios occur to compensate for hydraulic limitation. Reductions in Aₗ/Aₛin plants with greater hydraulic restriction allow LSC values, and thus transpiration rates, to stay as high as plants with less hydraulic restriction. As there was no such compensation, LSC values, and thus transpiration rates, were much lower in branches of higher order. Transpiration rate is a good indication of rates of photosynthesis. Lower transpiration rate in higher order branches is thus a good indication of hydraulic limitation on rates of photosynthesis with increased branching order. Hydraulic resistance in nodes thus imposes an important limitation on size and/or age of L. laureolum individuals, and explains the apparent trade-off between longevity and degree of ramification in the Cape Proteaceae.
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Wu, Ruiting. "Some Fundamental Mechanisms of Hydraulic Fracturing." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10513.
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This dissertation focuses mainly on three topics: (1) mixed-mode branching and segmentation of hydraulic fractures in brittle materials, (2) hydraulic fracture propagation in particulate materials, and (3) hydraulic fracturing in water flooding conditions.
Mixed-mode loading is one of the primary causes of fracture branching and segmentation in brittle materials. We conducted the first laboratory experiments on the mixed mode I+III hydraulic fracturing. We found that a KIII/KI ratio as small as ~1% is sufficient for fracture front segmentation. In reality, such a small mode III component is always expected, for example, due to the small deviations of the fracture shape from planar. Thus, we concluded that fracture segmentation is likely to accompany growth of most, if not all, real hydraulic fractures. We also proposed a theoretical model that captures the main features of experimental observations and indicates the importance of the hydraulic effect of segmentation.
Particulate materials often exhibit pronounced non-linear behavior and yielding even at relatively small loads. In order to adequately describe hydraulic fracturing in particulate materials with low or no cohesion, plasticity at the crack tip must be explicitly considered. We investigated the shear band mechanism of strain localization at the fracture front. This mechanism takes into account the fact that cohesionless material can not bear tension, and is in compression everywhere, including near the fracture front. To verify the shear band hypothesis, we conducted numerical simulations of the plastic deformation at the tip of a fracture in particulate material with strain softening. Our model describes the shear bands by properly placed and oriented dislocations. The model results are consistent with experimental observations.
Water flooding, which in certain important cases, can result in processes resembly hydraulic fracturing by a low-viscosity fluid with extremely high leak-off. It is difficult to simulate this process in the laboratory. To investigate the fracture initiation mechanism in water flooding conditions, we conducted a numerical simulation of fluid injection into particulate material by using the discrete element code PFC2D. We also considered an analytical model of cavity initiation based on the fluidization mechanism. The estimates given by this model fit remarkably well with the numerical simulation results.
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Janebrink, Niklas. "Construction of tilt table with high loads : A construction with complete hydraulic system." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-33155.
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At Uddeholm AB, they today use two overhead cranes with chains to move and tilt steel sheets for visual inspection of surface defects. The tilting is done to give the operator a better view of these defects using reflection of light. The problem with this approach is that it is combined with danger of life with hanging load, in case a chain breaks. Therefore Uddeholm AB would like to develop a tilt table that can be mounted on their lift table they use today. To solve this problem, 5 concepts was developed using a product development process. The chosen concept was further developed into a product that met the defined load case to tilt the sheets, weighing up to 20 tonnes, 55 degrees. The design that was selected use two points of rotation and is driven by three hydraulic cylinders. The structure has been calculated by hand and with the structural mechanics software Ansys. To tilt the table a complete hydraulic system was developed and dimensioned. The hydraulic system has been calculated by hand and simulated by a computer program called Hopsan developed at Linköping University.<br>På Uddeholm AB använder man idag två traverser med kedjor för att flytta och tilta stålplåtar för syning av ytdefekter. Tiltningen sker för att operatören lättare ska kunna se dessa defekter med hjälp av ljusreflektioner. Problemet med detta arbetssätt är att det är förenat med fara för liv med hängade last då en kedja skulle kunna gå av. Därför vill Uddeholm AB ha hjälp att utveckla ett tiltbord som kan monteras på deras lyftbord som används idag. I detta arbete togs det fram 5 koncept med hjälp av en produktutvecklingsprocess för att lösa problemet. Ett koncept valdes som utvecklades till en produkt som klarar det definierade lastfallet att tilta plåtar som väger upp till 20 ton 55 grader. Den valda designen som valdes använder två rotationspunkter och drivs av 3 hydraulcylindrar. Konstruktionen beräknades för hand och med strukturmekanikprogrammet Ansys. För att driva konstruktionen utvecklades och dimensionerades även ett komplett hydraulsystem. Hydraulsystemet har beräknats för hand och simulerats av ett datorprogram som kallas för Hopsan som utvecklats vid Linköpings universitet.
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Huňka, Jan. "Stavěcí mechanismus štěrbiny kuželového drtiče." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232135.
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This master’s thesis deals with the obtuse-angled cone crushers especially about design of the individual parts of the adjustment mechanism. Most space is devoted to functional calculation and subsequent technical construction of the new design of obtuse-angled crusher where the output setting is adjusted using the motion thread and hydraulic locking system for compensating the thread clearance. The parameters are chosen with regard to the already established older types of cone crushers produced by PSP Engineering, a.s. An inseparable part is the calculation verifying the functionality of the motion thread and gearing. Another essential part of this work are stress analysis of the slot adjusting mechanism design using finite element method and considering two states - adjusting of the slot and crushing itself.
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Fiala, Lukáš. "Výpočty jeřábových lan." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401516.
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This master thesis deals with calculation of steel wire ropes for cranes. Concretely is acted about calculation of wire ropes overhead crane manufactured by KRÁLOVOPOLSKÁ a.s. designed for load capacities up to 25 000 kg, which is situated at hall of steelworks. Further, the calculation of wire ropes different overhead crane was made to compare the results. The solution includes calculation made using valid standards ČSN 27 0100, DIN 15020-1, FEM 1.001 and ČSN EN 13001-3-2. Finally, the procedures are evaluated and compared with each other.
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Astete, Werner, and Polus Yonan. "Grundkurs i EPANET 2 : Ett förslag på hur e-lärande kan användas för att främja ett djupinriktat lärande." Thesis, KTH, Byggteknik och design, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-172389.
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Lärande med elektroniska medel har potentialen att revolutionera lärande. Via datorskärmen kan man enkelt åskådliggöra fysikaliska fenomen och underlätta arbetet för läraren. Om en utbildning bedrivs elektroniskt med hjälp av en dator och på distans uppstår en del svårigheter men samtidigt möjligheter, jämfört med en traditionell utbildning med fysisk närvaro i en skola. Datorer ger möjligheten att ta hänsyn till pedagogiska aspekter som kan effektivisera lärande. I dagens läge finns det inte ett utarbetat sätt att lära ut med elektroniska medel som garanterar ett gott lärande resultat. Hur en elektronisk kurs utformas är upp till läraren och institutionen som erbjuder kursen. I denna rapport ger vi ett enkelt förslag på hur vi anser en elektronisk kurs bör vara utformad samt det innehållet i kursen bör täcka.<br>Teaching by electronic means has the potential to revolutionize teaching. The screen of the computer can easily visualize physical phenomenon and facilitate the work of the teacher. If an education is conducted electronically and by distance it creates some difficulties but at the same time opportunities, compared to traditional education with a physical presence at a school. Today there is no prepared way to teach by electronic means that guarantees good teaching results. How an electronic course is formed is decided by the teacher and the institution offering the course. In this report we give a simple suggestion of how we consider an electronic technics course should be formed and what the course content should cover.
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Novák, Martin. "Návrh hydraulického okruhu pojezdu vibračního válce ASC 110." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401545.
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This thesis presents a proposal of newly designed concept for travel hydraulic circuit of vibratory single drum roller ASC 110. The maximum machine gradeability was chosen as the main parameter for hydraulic circuit proposal. After selecting the new hydraulic travel concept, suitable hydraulic components have been selected. Length and local losses for two different machine speeds were calculated for sufficient hydraulic circuit design. Hydraulic losses have also been calculated for use in different climatic conditions. A new machine cooling concept has also been proposed. Heating and cooling curves of hydraulic circuit were calculated. For the purpose of comparing gradeability and energy balance of the newly designed travel concept compared to the existing one currently in mass production, both machines were fitted with measuring points. On both machines were measured for example, pressure, flow and temperature in each hydraulic circuit branch and others. From the time dependencies of the above-mentioned parameters it was possible to determine the energy efficiency of the newly designed concept. To assess the maximum gradeability, the slope of the hill was measured. Comparing the two machines, it has been found that the two hydraulic circuit solution has significantly improved traction properties in demanding machine applications, especially when driving uphill and downhill. This concept also affects less fuel consumption and places less demand on the hydraulic oil cooler due to its energy efficiency.
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Ošlejšek, Jan. "Hydraulicko-elektrický systém zajišťující paralelitu chodu beranu vůči stolní desce hydraulického lisu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228215.
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The aim of the diploma thesis is design construction and calculation of mechanism for parallel run of ram and adjusting position of ram in the face of table board of vertical hydraulic press. First part of thesis is about design calculation of vertical hydraulic press ram. Second part focuses on design calculation of ram and hydraulic cylinders. Third part solves design and construction of positioning hydraulic–electric system. Final fourth part analyses press construction from aspects of safeness, riskiness and economical factors.
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Daly, Brian R. "Numerical modelling of distillation tray hydraulics." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361074.
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Dalziel, Stuart Bruce. "Two-layer hydraulics : maximal exchange flows." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292204.
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Edström, Sandra, and Jessie Stachowicz. "Strömingsbild i spillvatteninstallation : En studie på spridningsfenomen av spillvatten till golvbrunn." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280069.
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Ett avloppssystems syfte är att avleda spillvatten med säkerhet för användaren, det är därför viktigt att den hydrauliska prestandan i systemet är garanterad för den avsedda tillämpningen. Spillvatteninstallationer i Sverige ska därför utföras korrekt enligt lagkraven i Plan- och bygglagen samt funktionskraven i Boverkets byggregler. Idag används riktlinjerna i svensk byggnorm SBN 80 och den svenska standarden SS-EN 12056-2 för dimensionering, dock har det observerats fekalier i duschens golvbrunn även fast att dessa riktlinjer har följts. Projektets frågeställning är därför: Varför hamnar fekalier i duschens golvbrunn? Projektet inleds med en litteraturstudie om den teoretiska bakgrunden av strömningsmekanik i cirkulära halvfyllda rör och befintliga studier på den hydrauliska prestandan i avloppssystem. För att besvara frågeställningen används en experimentell metod. Experimenten behandlar en undersökning av strömningsbild och bakspolning på två olika installationer som är dimensionerade enligt SBN 80. Det empiriska resultatet visade tydligt att positionen av förminskningen till anslutningsledning från duschbrunn har en stor betydelse för risken av bakspolning. Slutsatsen blev att en position i överkant på den liggande stamledningen ger en definitiv lösning för att stoppa bakspolningen helt.<br>The purpose of a sewer system is to divert wastewater with safety for the user, therefore it is important that the hydraulic capacity of the system is guaranteed for the intended application. Wastewater installations in Sweden must therefore be installed correctly in accordance with the statutory requirements of the Planning and Building Act and the functional requirements of Boverket's building rules. Today, the guidelines in Swedish building standard SBN 80 and the Swedish standard SS-EN 12056-2 are used for constructing the installations, however, fecal have been observed in the shower well even though the guidelines have been followed. The project's question is therefore: Why does fecal appear in the shower well? The project begins with a literature study on the theoretical background of flow mechanics in circular semi-filled pipes and existing studies on the hydraulic capacity of the drainage system. An experimental method is used to answer the issue of the study. The experiments deal with a study of the flow pattern and the backflow on two different installations that are dimensioned according to SBN 80. The empirical result clearly showed that the position of the reduction to the shower well connection pipe is of great importance for the risk of backflow. The conclusion was that a position at the top of the horizontal pipe provides a definitive solution to stop the backflow completely.
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Kozelek, Petr. "Vyjížděcí stůl hydraulického zapracovávacího lisu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231066.
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This thesis deal with the construction proposal of the moving bolster hydraulic try-out press with roll-up cover the bottom cross beam. Hydraulic try-out press is used for testing dies. Moving bolster is used for remove of testing die from the working area of the press. Roll-up cover is designed to protect the bottom cross beam against damage and dirt snapping. Part of this thesis is design a railway track, design of driving mechanism, strength calculation of all functional components, design of welded frame and mechanism of the roll-up cover including safety cover. Designed device is detail proposed in the 3D software. The thesis contains drawing documentation assembly drawings movig bolster, mechanism of roll-up cover and welded frame consisting of welded and machined parts.
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Sim, Youngjong. "Mechanics of complex hydraulic fractures in the Earth's crust." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-08202004-144611/unrestricted/Sim%5FYoungjong%5F200412%5FPhD.pdf.
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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2005.<br>Puzrin, Alexander M., Committee Member ; Rix, Glenn J., Committee Member ; Mayne, Paul W., Committee Member ; Lowell, Robert P., Committee Member ; Germanovich, Leonid, Committee Chair ; Xu, Wenyue, Committee Member ; Van Dyke, Peter, Committee Member. Vita. Includes bibliographical references.
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Mighani, Saied 1989. "Some rock mechanics problems with application for hydraulic fracturing." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122224.
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Thesis: Ph. D. in Geophysics, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2019<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 185-205).<br>Hydraulic fracturing is an essential tool used to enhance connectivity in shale gas reservoirs by maximizing the intersection between the hydraulic fracture (HF) and pre-existing natural fractures (NF) or faults. The technique is most effective when the hydraulic fracture crosses natural fractures rather than arresting on them. Experiments conducted to examine the interaction between HF and artificial pre-existing faults suggest that the coupling of diffusivity and fault slip is an important element of the HF-fault interaction problem. Fault slip, once activated is associated with an apparent increase in diffusivity. Whether the hydrofracture crosses or arrests on the pre-existing fault is also affected by surface roughness, differential stresses, and fault slip mode (i.e., stable or stick-slip sliding). Calibrated piezoelectric transducers were used to measure acoustic emissions (AE) generated during HF and fault slip.<br>Moment tensor analysis of these events was used to distinguish pure tensile, shear, and possibly closure events during the experiments. Seismic moment magnitudes were approximately -7 for events during the initiation of the HF and about -5 for events during fault slip. Such a low ratio of seismic moments for tensile and slip events may explain the small numbers of tensile events recorded during reservoir stimulations. I also studied the time-dependent behavior in shales to gain insight into the post-stimulation efficiency of exploitations. Shale experiences strain hardening and compaction during loading by both isostatic (pressure-driven) and differential stress (shear-driven). Transient creep strain increased linearly with log(time), possibly transitioning to constant rate in timescale of several days. Motivated by the multi-scale nature of heterogeneities in shales, I examined the micromechanics of deformation using the nano-indentation technique.<br>Elastic and creep moduli found in nano-indentation and triaxial tests agreed within a factor of 2, but within that factor, the creep strength may depend on spatial scale.<br>by Saied Mighani.<br>Ph. D. in Geophysics<br>Ph.D.inGeophysics Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences
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Du, Jing. "Geophysical inversion of far-field deformation for hydraulic fracture and reservoir information /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Quesada, Díaz Raquel. "Horseshoe Bending Machine : Bending Mechanism." Thesis, Högskolan i Skövde, Institutionen för teknik och samhälle, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-9432.
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Horseshoes are manufactured metal plates developed in an extensive assortment of materials and shapes and their main function is to protect the horse’s hooves and legs against abrasion and rupture. After a certain period of time the horseshoes are lost, worn out, or the hoof needs to be treated. Horseshoeing is a repetitive time consuming process for the farrier who has to heat the horseshoe inside a forge until it reaches the required temperature and shape it with a hammer until it fits perfectly to the horses’ hoof. The main goal of this project is to develop a horseshoe bending machine able to shape the horseshoe so its shape fits perfectly the horse’s hoof. The calculation of the bending force needed to be applied to the horseshoe in order to provoke a plastic deformation will be done with Euler-Bernoulli beam theory. The bending force is then used to design and dimension each element of the bending mechanism so that it may be able to resist the stresses and prevent the parts from collapsing during its working life span. A study of the springback effect will be done followed by the analysis of the hertzian contact stresses between the rollers and the horseshoe. In addition, a clamping system is selected to constrain the movements of the horseshoe during the bending process. This machine will reduce the final user’s horse maintenance costs at the same time that makes the fitting process easier and less demanding, which will improve the farrier’s working life span and quality.
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Ismail, Azzura. "Seawater as a hydraulic fluid : corrosion mechanisms and rates of engineering materials." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7320/.
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With the increasing demand for environmentally friendly hydraulic fluids in the oil and gas sector, recent advances in hydraulic technology have sparked renewed interest in the application of water instead of oil. For industry, using seawater as a hydraulic fluid would bring many benefits as it can be discharged to the sea. The main corrosion challenges associated with the use of seawater are addressed in this study, particularly on how to extend the material life when corrosion attack is likely to be very severe. On the other hand, the material’s degradation which is common in subsea applications is studied in detail which includes how corrosion mechanisms occur. The materials chosen in this research are those which are used extensively in subsea applications especially in Directional Control Valves (DCV) and piping operating with hydraulic fluids namely: (1) carbon steel, (2) stainless steel, and (3) cermet alloys (WC-Ni and WC-Co). As an active material, carbon steelcorrodes in a general way whereas passive materials such as stainless steel are more prone to localised corrosion which is often more catastrophic and difficult to predict and detect. However, cermets alloys (WC-Ni and WC-Co) which consist of metals and ceramics may exhibit both active and passive trends. Electrochemistry methods which are used in this study provide quantitative data which demonstrates different major corrosion parameters. Generally, temperature, oxygen, anions and pH are the main parameters that affect corrosion attack. In this research the effects of temperature, sulphate to chloride ratio and oxygen were studied on corrosion performance of DCV materials and compared the performance in seawater with a typical commercial hydraulic fluidHW443. From the analysis, it shows that temperature has a severe impact on corrosion rate, but alteration of sulphate to chloride ratio could decrease the corrosion rate close to HW443. Therefore, it is clear that by changing the sulphate/chloride ratio in seawater and adding green corrosion inhibitor similar performance to that compared to the use of commercial hydraulicfluids yet reduce the environmental harm on discharge could be attained. The thesis also presents information ofgeneric interest in corrosion of carbon steel and other materials of interest in subsea environments. Corrosion trends of carbon steel, stainless steel and WC-cermets and their prevalent corrosion mechanisms (from electrochemical analysis) are discussed.
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Chang, Hong. "Hydraulic Fracturing in Particulate Materials." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4957.
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For more than five decades, hydraulic fracturing has been widely used to enhance oil and gas production. Hydraulic fracturing in solid materials (e.g., rock) has been studied extensively. The main goal of this thesis is a comprehensive study of the physical mechanisms of hydraulic fracturing in cohesionless sediments. For this purpose, experimental techniques are developed to quantify the initiation and propagation of hydraulic fractures in dry particulate materials. We have conducted a comprehensive experimental series by varying such controlling parameters as the properties of particulate materials and fracturing fluids, boundary conditions, initial stress states, and injection volumes and rates. In this work, we suggest principle fundamental mechanisms of hydraulic fracturing in particulate materials and determine relevant scaling relationships (e.g., the interplay between elastic and plastic processes).
The main conclusion of this work is that hydraulic fracturing in particulate materials is not only possible, but even probable if the fluid leak-off is minimized (e.g., high flow rate, high viscosity, low permeability). Another important conclusion of this work is that all parts of the particulate material are likely to be in compression. Also, the scale effect (within the range of the laboratory scales) appears to be relatively insignificant, that is, the observed features of fractures of different sizes are similar.
Based on the observed fracture geometries, and injection pressures we suggested three models of hydraulic fracturing in particulate materials. In the cavity expansion or ??e driving model, the fracturing fluid is viewed as a sheet pile (blade) that disjoints the host material, and the cavity expansion occurs at the fracture (blade) front. The shear banding model is also consistent with a compressive stress state everywhere in the particulate material and explains the commonly observed beveled fracture front. The model of induced cohesion is based on the fluid leak-off ahead of the fracture front. The induced cohesion may be caused by the tensile strain near the fracture tip (where the stress state is also compressive), which, in turn, induces the cavitation of the leaked-off fluid and hence capillary forces.
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Jonsson, Patrick. "Smoothed particle hydrodynamics in hydropower applications : modeling of hydraulic jumps." Licentiate thesis, Luleå tekniska universitet, Strömningslära och experimentell mekanik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16867.
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In present thesis, the Lagrangian particle based method Smoothed ParticleHydrodynamics (SPH) is used to model two-dimensional problems associated with hydropower applications such as dam break evolution and hydraulic jumps. In the SPHmethod, the fluid domain is represented by a set of non-connected particles which possess individual material properties such as mass, density, velocity, position and pressure. Besides representing the problem domain and acting as information carriers the particles also act as the computational frame for the field function approximations. As the particles move with the fluid the material properties changes over time due to interaction with neighbouring particles. The adaptive nature of the SPH-method together with the nonconnectivity between the particles results in a method that is able to handle very large deformations as is the case for highly disordered free-surface flows such as hydraulic jumps.The dam break case was used as a model validation test case where the response of different parameter settings was explored. The SPH spatial resolution and the choice of artificial viscosity (a term in the momentum equation) constants had a major impact on the results. Increasing the spatial resolution increased the number of flow features resolved and setting the constants equal to unity resulted in a highly viscous and unphysical solution.Following the parameter study, the work focused on SPH simulations of hydraulic jumps. A hydraulic jump is a rapid transition from supercritical flow to subcritical flow characterized by the development of large scale turbulence, surface waves, spray, energy dissipation and considerable air entrainment. Several features of the jump were explored using the SPH method and good agreement with theory and experiments was obtained for e.g. the conjugate depth and the mean free surface elevation in the roller section. However, the free surface fluctuation frequencies were over predicted and the model could not capture the decay of fluctuations in the horizontal direction.<br>Godkänd; 2013; 20130425 (patjon); Tillkännagivande licentiatseminarium 2013-05-29 Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Patrick Jonsson Ämne: Strömningslära/Fluid Mechanics Uppsats: Smoothed Particle Hydrodynamics in Hydropower Applications Modelling of Hydraulic Jumps Examinator: Professor Staffan Lundström, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Doktor, forskare Gustaf Gustafsson, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Tid: Torsdag den 20 juni 2013 kl 09.00 Plats: E231, Luleå tekniska universitet
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Sundaramurthy, Surya Narayanan. "New Sensing Techniques for Structural Health Monitoring of Hydraulic Hose, Composite Panels, and Biodegradable Metal Implants." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307105130.
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Khattab, Hussein A. "Finite element response modeling of crack geometries induced by hydraulic fracturing /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487261919112032.
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Johnson, Jonas. "The Cardiac State Diagram : A new method for assessing cardiac mechanics." Doctoral thesis, KTH, Medicinsk avbildning, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202743.
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Guinart, Trayter Xavier, and Aceret Jordi Orpella. "Hydraulic Regenerative System for a Light Vehicle." Thesis, Linköping University, Fluid and Mechanical Engineering Systems, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57120.
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<p>The thesis is based in a constructed light vehicle that must be improved by adding a hydraulic energy recovery system. This vehicle named as TrecoLiTH, participated in the Formula Electric and Hybrid competition (Formula EHI) 2009 in Italy -Rome- and won several awards.</p><p>This system consists in two hydraulic motors hub mounted which are used to store fluid at high pressure in an accumulator when braking. Through a valve the pressure will flow from the high pressure accumulator to the low pressure one, and consequently the vehicle will get extra acceleration.</p><p>This thesis consists in finishing the assembly and testing it, as the main idea was already thought and some of the necessary parts were acquired before. Firstly, a quick overview of the bike is done and the current state of it at the end of the thesis is discussed. After that, the mechanism used to actuate the system is developed and explained, with which some CAD software was used to design and make some FEA. Straight afterwards the work focused on the tests and its development. A quick discussion about what tests should be done, the preparations and also the way that some measurements were done is commented. In order to do these measurements a data acquisition device and some software to deal with it was used.</p><p>Thereupon, calculations to know if the system auto-compensates the weight added, causing more rolling resistance, and the oil frictions are done. In this part the performance and reliability of the system is discussed, as well as the feelings of the driver. Finally, improvements and possible modifications are listed with the aim of upgrade the vehicle, the system and the way of work.</p>
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Biswas, Sharbaree. "Study of cohesive soil-granular filter interaction incorporating critical hydraulic gradient and clogging." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060221.100311/index.html.
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Joy, Dawn, and Karthik Sekaran. "Electronic Pump Control and Benchmarking of Simulation Tools : AMESim and GT Suite." Thesis, Linköpings universitet, Fluida och mekatroniska system, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-69567.
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Load sensing pumps in hydraulic system of wheel loaders helps in increasing the energy efficiency of wheel loaders. Present day machines have hydro mechanical load sensing system. After the advent of hydro mechanical load sensing concept, over the years, lots of research has been carried out relevant to electro hydraulic load sensing, trying to control the pump electronically. Currently, Volvo Construction Equipments (VCE) is interested in investigating the possibility of implementing electro hydraulic load sensing system in the wheel loaders. Research works has shown existence of several configurations of electro hydraulic load sensing pumps. Successful simulation results of an electro hydraulic load sensing pump configuration would provide a backing for the proposal of building and testing that configuration of electro hydraulic load sensing pump prototype. Also, the thesis work aims in benchmarking hydraulic system simulation capabilities of AMESim and GT- Suite by simulating the existing hydro mechanical load sensing system in both in both the simulation packages.<br>The thesis work has been carried out at Virtual Product Development (VPD) division of Volvo Construction Equipments (VCE), Eskilstuna, Sweden.
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Hurt, Robert S. "Toughness-dominated hydraulic fractures in cohesionless particulate materials." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43708.
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This work shows that toughness (resistance) to fracture propagation is an inherent characteristic of cohesionless particulate materials, which is significant for understanding hydraulic fracturing in geotechnical, geological, and petroleum applications. We have developed experimental techniques to quantify the initiation and propagation of fluid-driven fractures in saturated particulate materials. The fracturing liquid is injected into particulate materials, where the fluid flow is localized in thin crack-like conduits. By analogy, we call them 'cracks' or 'hydraulic fractures'. Based on the laboratory observations and scale analysis, this work offers physical concepts to explain the observed phenomena.
When a fracture propagates in a solid, new surfaces are created by breaking material bonds. Consequently, the material is in tension at the fracture tip. In contrast, all parts of the cohesionless particulate material (including the tip zone of hydraulic fracture) are likely to be in compression. In solid materials, the fluid front lags behind the front of the propagating fracture, while the lag zone is absent for fluid-driven fractures in cohesionless materials. The compressive stress state and the absence of the fluid lag are important characteristics of hydraulic fracturing in particulate materials with low, or no, cohesion.
Our experimental results show that the primary factor affecting peak (initiation) pressure is the magnitude of the remote stresses. The morphology of fracture and fluid leak-off zone, however, changes significantly not only with stresses, but also with other parameters such as flow rate, fluid rheology, and permeability. Typical features of the observed fractures are multiple off-shots and the bluntness of the fracture tip. This suggests the importance of inelastic deformation in the process of fracture propagation in cohesionless materials. Similar to solid materials, fractures propagated perpendicular to the least compressive stress. However, peak injection pressures are significantly greater than the maximum principle stresses in the experiments. Further, by incorporating the dominate experimental parameters into dimensionless form; a reasonable power-law fit is achieved between a dimensionless peak injection pressure and dimensionless stress.
Scaling indicates that there is a high pressure gradient in the leak-off zone in the direction normal to the fracture. Fluid pressure does not decrease considerably along the fracture, however, due to the relatively wide fracture aperture. This suggests that hydraulic fractures in unconsolidated materials propagate within the toughness-dominated regime. Furthermore, the theoretical model of toughness-dominated hydraulic fracturing can be matched to the experimental pressure-time dependences with only one fitting parameter. Scale analysis shows that large apertures at the fracture tip correspond to relatively large 'effective' fracture (surface) energy, which can be orders of magnitude greater than typical for hard rocks.
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Tang, Yin-tong. "Rock stress determination in Hong Kong Island by using hydraulic fracturing method /." View the Table of Contents & Abstract, 2005. http://sunzi.lib.hku.hk/hkuto/record/B36357625.
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Van, Der Merwe Carel Wagener. "A peridynamic model for sleeved hydraulic fracture." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95993.
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Thesis (MEng)--Stellenbosch University, 2014.<br>ENGLISH ABSTRACT: Current numerical methods in the eld of hydraulic fracturing are based mainly on
continuum methods, such as the Finite Element Method (FEM) and the Boundary Element
Method (BEM). These methods are governed by Linear Elastic Fracture Mechanics
(LEFM) criteria, which su er from the inherent
aw of a non-physical stress representation
at the fracture tip. In response to this, a non-local method is proposed, namely
the peridynamic theory, to model sleeved hydraulic fracture. A 2D implicit quasi-static
ordinary state based peridynamic formulation is implemented on various benchmark
problems, to verify the ability to capture constitutive behaviour in a linear elastic solid,
as well as, the quanti cation of adverse e ects on the accuracy of the displacement solution,
due to the nature of the non-local theory. Benchmark tests consist of a plate in
tension, where convergence to the classical displacement solution, non-uniform re nement
and varying cell sizes are tested, as well as, a thick walled cylinder with internal
pressure, where three di erent loading techniques are tested. The most accurate loading
technique is applied to the sleeved fracture model, in order to simulate fracture initiation
and propagation. This model is then veri ed and validated by using the Rummel &
Winter hydraulic fracturing model and experimental results, respectively. Displacement
error minimisation methods are implemented and as a result, the displacement solutions
for a plate in tension converges to the analytical solution, while the thick walled cylinder
solutions su er from inaccuracies due to an applied load on an irregularly discretized
region. The fracture initiation test captures the fracture tip behaviour of the Rummel
& Winter model and the fracture propagation test show good correlation with experimental
results. This research shows that the peridynamic approach to sleeved hydraulic
fracture can yield a realistic representation of fracture initiation and propagation, however,
further research is needed in the area of a pressure load application on a solid using
the peridynamic approach.<br>AFRIKAANSE OPSOMMING: Huidige numeriese metodes in die veld van hidrouliese breking is hoofsaaklik gebaseer
op kontinuum metodes, soos die Eindige Element Metode (EEM) en die Rand Element
Metode (REM). Hierdie metodes word beheer deur Linie^ere Elastiese Breukmeganika
(LEB) kriteria, wat ly aan die inherente gebrek van 'n nie- siese voorstelling van die
spanning by die fraktuur punt. Om hierdie probleme aan te spreek, word 'n nie-lokale
metode voorgestel, naamlik die peridinamiese teorie, om gehulsde hidrouliese breking
te modelleer. 'n 2D implisiete kwasi-statiese ordin^ere toestand gebaseerde peridinamika
formulering word ge mplimenteer op verskeie norm probleme, om te veri eer of dit oor
die vermo e beskik om die konstitutiewe gedrag van 'n linie^ere elastiese soliede materiaal
te modeleer, asook die kwanti sering van nadelige e ekte op die verplasings oplossing as
gevolg van die natuur van die nie-lokale teorie. Normtoetse bestaan uit 'n plaat in trek
spanning, waar konvergensie na die klassieke verplasings oplossing, nie-uniforme verfyning
en vari^eerende sel groottes getoets word, asook 'n dikwandige silinder onder interne
druk, waar drie verskillende belasting aanwendingstegnieke getoets word. Die mees akkurate
belasting aanwendingstegniek word dan gebruik in die gehulsde hidrouliese breking
model, om fraktuur aanvangs en uitbreiding na te boots. Die model word dan geveri-
eer deur die Rummel & Winter hidrouliese breking model en eksperimentele resultate,
onderskeidelik. Fout minimering metodes word toegepas en as 'n resultaat, konvergeer
die verplasing oplossing vir die plaat na die analitiese oplossing, terwyl die oplossing
van die dikwandige silinder onakuraathede toon as gevolg van 'n toegepaste belasting
op 'n onre elmatig gediskretiseerde gebied. Die modellering van die fraktuur inisi ering
by die fraktuur punt, stem goed ooreen met die Rummel en Winter voorspelling en die
fraktuur uitbreiding stem goed ooreen met eksperimentele resultate. Hierdie navorsing
toon dat die peridinamiese benadering tot gehulsde hidrouliese breking wel die fraktuur
inisi ering en uitbreiding realisties kan modelleer, maar nog navorsing word wel benodig
in die area waar 'n druk belasting op 'n peridinamiese soliede model toegepas word.
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Hewett, Caspar Julian Mnaser. "Unconditionally stable finite difference schemes for the solution of problems in hydraulics." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275595.
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Yan, Li. "Hydraulic gradient similitude method for geotechnical modelling tests with emphasis on laterally loaded piles." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/31899.
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A study has been undertaken to evaluate and apply the hydraulic gradient similitude
method to geotechnical model testings. This method employs a high hydraulic gradient across granular soils to effectively increase self-weight stresses in the model. Testing principle and procedures are presented, and the factors affecting test results discussed. An apparatus (UBC-HGST) using this testing principle has been developed.
Three applications are presented in which the hydraulic gradient similitude method is evaluated, and the existing concepts and methods of analysis for the problems
studied are examined.
In the footing tests, it is found that the scaling laws implied in the hydraulic gradient
modelling test are satisfied, and are similar to those of the centrifuge modelling technique. Load-settlement curves are found to be similar to those in centrifuge tests. The test results illustrate the importance of the stress level in the load-settlement responses.
Terzaghi's bearing capacity formula is compared with the observed bearing capacities under different stress levels. It is found that due to the stress level effects,
the bearing capacity coefficient, Nγ, decreases linearly with footing width on the log-log scale which is in accordance with other model study and analytical results.
In the downhole and crosshole seismic tests, results are used to evaluate the empirical
equations that relate shear wave velocity and soil stresses in terms of field stress condition. It is found that although the various equations can predict the insitu shear wave velocity profile reasonably well, only the equation which is based on the significant
stresses in the wave propagation and particle motion directions can predict the variation of velocity ratio between the downhole and SH crosshole tests. It is also found that the stress ratio has some effects on the downhole (or SV crosshole) tests,
but not on the SH crosshole tests. This indicates that only the stress ratio in the plane of wave propagation is important to the shear wave velocity. Comparison between
the downhole and SH crosshole tests shows that the structure anisotropy was about 10% in terms of shear wave velocity. Prediction of Ko values using shear wave measurement is evaluated, and its practical difficulties are addressed.
In the laterally loaded pile tests, the pile response to static and cyclic loadings at various stress levels controlled by the hydraulic gradients is examined in terms of pile head response, pile bending moment and soil-pile interaction P-y curves. For the static loading, pile head response and bending moment are found to be significantly affected by the soil-pile relative stiffness, pile diameter, loading condition and pile head fixity. However, little effects of loading eccentricity and pile head fixity are found on the P-y curves. While pile diameter is found to have effects on the P-y curves at large pile deflection, its effects are negligible at small deflecton range. The effects of relative soil-pile stiffness on the P-y curves due to stress levels can be normalized by the soil modulus and pile diameter for the curves below 1 pile diameter, as computed by the plane strain finite element analysis. Two methods of generating P-y curves are suggested, and found to give satisfactory results as compared with the test data and the prediction given by API code (1987). For cyclic loading, different pile responses are observed in "one-way" as compared to "two-way" cyclic loading. The cyclic P-y curves are derived, and found to be highly nonlinear and hysteretic, and change with number of loading cycles. From these studies, it is shown that the hydraulic gradient similitude method provides a simple and inexpensive means of model testing for many geotechnical engineering problems and adds to the data base from which methods of analysis can be evaluated.<br>Applied Science, Faculty of<br>Civil Engineering, Department of<br>Graduate
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Heinze, Alexander. "Modelling, simulation and control of a hydraulic crane." Thesis, Växjö University, School of Technology and Design, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-1932.
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<p>The objective of this thesis is to develop a model that represents the dynamics of a hydraulically operated forestry crane. The model was derived with the traditional Euler-Lagrange formalism and considers the crane mechanics, three double-acting hydraulic cylinders and the valve control unit. On the basis of the derived model we reproduced the entire crane model in MATLAB in order to run simulations herewith. This gave us the possibility to do parameter changes for further studies of the crane in motion.</p><p>Another major goal within the thesis work was to estimate cylinder friction of the hydraulic actuators. We built up a test rig and used double-acting cylinders for determing their frictional behaviour. For this, we ran open-loop experiments in order to create velocity-friction maps that represented the static friction force of the cylinders. In this concern, we varied system pressure and cylinder load to study their influence on the friction force. By means of the derived static friction maps we approached the cylinder’s dynamic friction behaviour and applied both step and ramp control inputs to examine the spring-damping characteristics of the microspoic bristles in the contacting area. The dynamic friction experiments have been exerted in the fashion of the LuGre model. As a result we acquired different nominal friction parameters that we necessarily used to develope adequate friction models.</p><p>A third objective of this thesis was to establish a crane-tip control. Instead of a traditional control, providing a direct relationship between joystick input and cylinder extension, the focus was to build up a control for the end-effector’s trajectory in a two-dimensional frame. This could be achieved by using inverse kinematics in order to determine the required joint angles that corresponded to the desired position of the crane-tip.</p><p>The work also contains a CD including all developed MATLAB models that have been written within this project.</p>
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Andersson, Håkan. "A Co-Simulation Approach for Hydraulic Percussion Units." Licentiate thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-151018.
Full textAbstract:
This Licentiate of Engineering thesis concerns modelling and simulation of hydraulic percussion units. These units are often found in equipment for breaking or drilling in rock and concrete, and are also often driven by oil hydraulics, in which complex fluid-structure couplings are essential for their operation. Current methodologies used today when developing hydraulic percussion units are based on decoupled analyses, which are not correctly capturing the important coupled mechanisms. Hence, an efficient method for coupled simulations is of high importance, since these mechanisms are critical for the function of these units. Therefore, a co-simulation approach between a 1D system simulation model representing the fluid system and a structural 3D FE-model is proposed. This approach is presented in detail, implemented for two well-known simulation tools and evaluated for a simple but relevant model. The Hopsan simulation tool was used for the fluid system and the FE-simulation software LS-DYNA was used for the structural mechanics simulation. The co-simulation interface was implemented using the Functional Mock-up Interface-standard. The approach was further developed to also incorporate multiple components for coupled simulations. This was considered necessary when models for the real application are to be developed. The use of two components for co-simulation was successfully evaluated for two models, one using the simple rigid body representation, and a second where linear elastic representations of the structural material were implemented. An experimental validation of the co-simulation approach applied to an existing hydraulic hammer was performed. Experiments on the hydraulic hammer were performed using an in-house test rig, and responses were registered at four different running conditions. The co-simulation model was developed using the same approach as before. The corresponding running conditions were simulated and the responses were successfully validated against the experiments. A parameter study was also performed involving two design parameters with the objective to evaluate the effects of a parameter change. This thesis consists of two parts, where Part I gives an introduction to the application, the simulation method and the implementation, while Part II consists of three papers from this project.
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Li, Xu. "Dual-porosity structure and bimodal hydraulic property functions for unsaturated coarse granular soils /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202009%20LI.
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Thein, Myint. "Experimental investigation of flow resistance and velocity distributions in a rectangular channel with large bed-roughness elements." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/19580.
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