Dissertations / Theses on the topic 'Velocity on the wall'
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Gresko, Lawrence Sebastian. "Characteristics of wall pressure and near-wall velocity in a flat plate turbulent boundary layer." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14373.
Full textÖsterberg, Klas. "Vascular wall responses to bypass grafting : studies in mice /." Göteborg : Dept. of Molecular and Clinical Medicine, Vascular Surgery, Institute of Medicine, Sahlgrenska Academy at Göteborg University, 2008. http://hdl.handle.net/2077/9437.
Full textDisotell, Kevin James. "A semi-empirical model of the wall-normal velocity induced by flow-shaping plasma actuators." Connect to resource, 2010. http://hdl.handle.net/1811/45413.
Full textHurst, Edward. "A numerical study of turbulent drag reduction using streamwise travelling waves of spanwise wall velocity." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/67161/.
Full textKöhler, Uwe. "3D phase contrast MRI : velocity-field visualisation and wall shear rate calculation in major arteries." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/22384.
Full textLoth, Francis. "Velocity and wall shear measurements inside a vascular graft model under steady and pulsatile flow conditions." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/15907.
Full textTamtomo, Kiono Berkah Fajar. "Study of wall velocity gradient and mass transfer on rotating cylinder and finned-cylinder in crossflow." Valenciennes, 2002. https://ged.uphf.fr/nuxeo/site/esupversions/2de35dda-200e-4237-8d4b-574007c70bf2.
Full textThis works deals with the measurement of the wall shear stress and mass transfer around a rotating cylinder alone and a rotating finned cylinder in cross flow by using the polarographic method for different Reynolds numbers and different α (peripheral speed/streamwise velocity). An inverse mass transfer method permits to correct the electronical signal. The corrected wall hear stress around the rotating cylinder show the presence of complex structures, especially in the upstream moving wall region. The mass transfer measured on the rotating cylinder leads to a correlation that takes into account the combined effects of rotation and cross flow. The second part of this work concerns the local measurement of the wall shear stress on the fin fixed to the cylinder. The high values of the wall shear stress measured on the fin are attributed to "horseshoe" vortices. It is shown that for low values of α, the distribution of the unsteady wall shear stress on the fin is similar to that observed in the steady case. Whan the rotation speed increases, the distribution of the wall shear stress tends towards that obtained in fluid at rest. A correlation between the rotation Reynolds number and mean Nusselt number on the fin is proposed by using a Reynolds analogy
Blake, James R. "On the assessment of blood velocity and wall shear rate in arteries with Doppler ultrasound : a validation study." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/4195.
Full textLunt, Tilmann. "Experimental investigation of the plasma-wall transition." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2008. http://dx.doi.org/10.18452/15837.
Full textIn the present work the streaming behavior of a magnetized argon plasma impinging on a neutralizing surface was investigated. For that purpose the ion velocity distribution was measured non-invasively as a function of the distance to the surface by means of Laser Induced Fluorescence. The spatial resolution was typically dz=0.5 mm. Two situations are investigated, (a): when practically the whole plasma streams onto a large target (diameter 100 mm), and (b): when the size of the target (diameter 15 mm) is significantly smaller than the diameter of the plasma column. In both cases the streaming velocity u was at least as high as the ion acoustic sound speed, as already predicted by Bohm in 1949. Under fusion relevant conditions this is the first direct observation of the Bohm criterion. Approaching the target surface the Mach number M=u/c_s increases from values of around 0.5 to 1 on typical scales of lambda_a=30 mm and lambda_b=5 mm, respectively. In order to explain these very short scale lengths the measured data were compared with a collisional-diffusive model in the case of (a) and with Hutchinson''s model[] in the case of (b). A good agreement was achieved in (a) by assuming a very low neutral gas temperature of about 400 K. In (b) the model fits the data excellently when the transport coefficient is chosen as high as D=20 m²/s. Such a high transport cannot be caused solely by diffusion. Partly it is explained by finite gyro-radii effects, but presumably time dependent phenomena, like drift waves, play an important role. In addition the dependence on the angle between surface normal and B-field was investigated. The supersonic fluxes found in the immediate vicinity of the surface are described fairly well by the model developed by Chodura[]. By contrast the size of the region, where Mach numbers greater one appear is significantly smaller than predicted.
Bermuske, Mike, Lars Büttner, and Jürgen Czarske. "Measurement uncertainty budget of an interferometric flow velocity sensor." SPIE, 2017. https://tud.qucosa.de/id/qucosa%3A35151.
Full textGarg, Chirag [Verfasser], Stuart S. P. [Gutachter] Parkin, Georg [Gutachter] Woltersdorf, and Christian [Gutachter] Back. "Investigating the effect of curvature on chiral domain wall velocity / Chirag Garg ; Gutachter: Stuart S. P. Parkin, Georg Woltersdorf, Christian Back." Halle (Saale) : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2019. http://d-nb.info/1210731932/34.
Full textAwasthi, Manuj. "High Reynolds Number Turbulent Boundary Layer Flow over Small Forward Facing Steps." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/33820.
Full textMaster of Science
Castagna, Marco. "An in vitro method for the error assessment of Phase Contrast Magnetic Resonance lmaging based velocity measurements and calculation of derived Wall Shear Stress." Thesis, Nantes, 2020. http://www.theses.fr/2020NANT1012.
Full textAtherosclerosis accounts for about 21% of deaths worldwide. It develops primarily in specific locations of the cardiovascular system where the Wall Shear Stress (WSS) can deviate more easily from its baseline values. Potential clinical applications of WSS as a biomarker rely on an accurate assessment of blood velocity in patients since it is defined from the derivative of blood velocity at the arterial wall. The present work aims to design and develop a hydraulic test rig to validate Phase Contrast Magnetic Resonance Imaging (PC MRI) velocity acquisitions and the computation of derived WSS. To do that, reference velocity profiles were obtained with Laser Doppler Velocimetry (LDV) and employed as a standard for direct comparison with PC MRI results. The experimental set-up was composed of an MRI compatible pump, flexible connection pipes, a test section, a reservoir, a working fluid, and a flowmeter. One standard 2D PC MRI and one standard 4D Flow MRI sequences were employed to obtain MRI velocity profiles, adjusting their parameters as in clinical practice. The WSS was calculated with the 2D and 3D methods proposed respectively by Stalder et al. and Potter et al. A second experimental campaign was performed with the refinement of the data spatial and temporal resolution, employing only the 4D Flow MRI sequence. Results indicated an excellent agreement between MRI and LDV velocity and WSS data. This study represents a reliable basis for any validation with LDV of 4D Flow MRI based methods for WSS calculation
Gliah, Omemah Rajab. "In Vitro Investigation of Cell-Free Layer Formation in Microchannels: Dependency on the Red Blood Cell Aggregation and Field of Shear." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37211.
Full textHalama, Lukáš. "Studium chování nenewtonských kapalin ve slit-flow reometru za podmínek nestabilního toku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-399291.
Full textJang, Jun-keun. "Study on the Application of Shear-wave Elastography to Thin-layered Media and Tubular Structure: Finite-element Analysis and Experiment Verification." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/217145.
Full textMa, Jieyan. "Development of numerical tools for hemodynamics and fluid structure interactions." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/development-of-numerical-tools-for-hemodynamics-and-fluid-structure-interactions(f7e72de2-c1f8-4d7a-aa2c-f2a4d239187f).html.
Full textBjarnegård, Niclas. "Aspects on wall properties of the brachial artery in man : with special reference to SLE and insulin-dependent diabetes mellitus." Doctoral thesis, Linköpings universitet, Institutionen för medicin och hälsa, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11273.
Full textІвіцький, Ігор Ігорович. "Пристінні ефекти в процесах течії полімерів у каналах переробного обладнання." Thesis, НТУУ "КПІ", 2016. https://ela.kpi.ua/handle/123456789/16117.
Full textThe dissertation is devoted to research presence, the nature and value of wall effects arising from the melt flow channels in polymer materials processing equipment. The method of determining the presence of wall effects polymeric material and the nature of these effects. Depending of the nature of wall effects developed methodology for determining the value of these effects in the material. Mathematical model of current polymer materials supplemented into account the effects of wall, depending on their nature and the material allowed us to create a universal approach to determining process parameters during the current numerical modeling. It was examine a numerical study of the influence of geometrical parameters of channel differences pressure between the absence of speed on the wall and consideration of wall effects. On the basis of empirical studies deduce equations to take into account when designing shelving effects without additional processing equipment of numerical studies.
Диссертация посвящена исследованию наличия, характера и величины пристенных эффектов, возникающих при течении расплава полимерных материалов в каналах перерабатывающего оборудования. Проведенный аналитический анализ современного состояния исследований течения полимера показал, что ранее рассматриваются отдельные вопросы пристенных эффектов при течении расплава полимера, однако они имеют ряд недостатков: не учитывают природу и характер возникновения пристенных эффектов в различных материалах, позволяют определить величину эффекта не во всем диапазоне сечений каналов, не позволяют использовать полученные данные для численного расчета с использованием систем автоматизированного проектирования. Разработан метод определения наличия пристенных эффектов в полимерном материале и природы этих эффектов. В зависимости от природы пристенных эффектов разработаны методики определения величины этих эффектов в материале, которые учитывают неньютоновские свойства материалов. Разработана методика проведения экспериментальных исследований на базе созданной экспериментальной установки для исследования пристенных эффектов. Проведены экспериментальные исследования с использованием трех типов полимерных материалов: полиэтилен низкого давления, полистирол, севилен. Также проведены эксперименты с использованием смазывающего агента для определения величины его влияния на пристенные эффекты. Установлены зависимости напряжения сдвига от скорости расплава материала на стенке, что позволило получить исходные данные для задания граничных условий при численном моделировании процесса Математическая модель течения полимерных материалов дополнена учетом пристенных эффектов в зависимости от их природы и материала, что позволило создать универсальный подход к определению параметров процесса течения при численном моделировании. Адекватность математической модели и граничных условий подтверждается сопоставлением результатов численного моделирования и экспериментальных данных, а также сопоставлением с существующими результатами исследований. Адекватность изотермического предположения проверялась числовым расчетом для изотермического режима и с учетом диссипации при постоянной температуре стенок. Адекватность экстраполяции результатов, полученных в экспериментальных исследованиях с цилиндрическими каналами на другие типы каналов, подтверждается проведением дополнительного опыта с капилляром прямоугольной формы, гидравлический диаметр которого совпадал с одним из исследуемых капилляров.Численное моделирование проводилось на каналах цилиндрической, конической и прямоугольной геометрии, а также на геометрии формующей головки экструдера. Граничными условиями на стенке каналов послужили данные, полученные в результате проведения экспериментальных исследований. Проведены численные исследования влияния геометрических параметров каналов на разность перепадов давления между условиями отсутствия скорости на стенке и учетом пристенных эффектов, а также влияния смазывающего агента. Установлено, что характер влияния геометрических параметров на разность перепадов давления имеет, в основном, нелинейный характер. Исследования показали, что при численном моделировании течения полимерного материала по геометрии формующей головки пренебрежение пристенными эффектами приводит к погрешности в полученных результатах от 11% до 22% в зависимости от материала. Для определения степени влияния параметров и создания регресивной модели процесса был проведен полный факторный эксперимент, который позволил вывести эмпирические уравнения, позволяющие учитывать пристенные эффекты при проектировании перерабатывающего оборудования без дополнительного проведения численных исследований. Разработаны конструкции экструзионных головок, позволяющих компенсировать влияние пульсаций расплава, которые возникают в результате действия пристенных эффектов, а также конструкция червяка экструдера, которая позволяет обеспечить поглощение пульсаций давления, возникающих в результате действия пристенных эффектов.Проведены численные исследования влияния геометрических параметров каналов на разность перепадов давления между условиями отсутствия скорости на стенке и учетом пристенных эффектов, а также влияния смазывающего агента. Установлено, что характер влияния геометрических параметров на разность перепадов давления имеет, в основном, нелинейный характер. Исследования показали, что при численном моделировании течения полимерного материала по геометрии формующей головки пренебрежение пристенными эффектами приводит к погрешности в полученных результатах от 11% до 22% в зависимости от материала. Для определения степени влияния параметров и создания регресивной модели процесса был проведен полный факторный эксперимент, который позволил вывести эмпирические уравнения, позволяющие учитывать пристенные эффекты при проектировании перерабатывающего оборудования без дополнительного проведения численных исследований. Разработаны конструкции экструзионных головок, позволяющих компенсировать влияние пульсаций расплава, которые возникают в результате действия пристенных эффектов, а также конструкция червяка экструдера, которая позволяет обеспечить поглощение пульсаций давления, возникающих в результате действия пристенных эффектов.Проведены численные исследования влияния геометрических параметров каналов на разность перепадов давления между условиями отсутствия скорости на стенке и учетом пристенных эффектов, а также влияния смазывающего агента. Установлено, что характер влияния геометрических параметров на разность перепадов давления имеет, в основном, нелинейный характер. Исследования показали, что при численном моделировании течения полимерного материала по геометрии формующей головки пренебрежение пристенными эффектами приводит к погрешности в полученных результатах от 11% до 22% в зависимости от материала. Для определения степени влияния параметров и создания регресивной модели процесса был проведен полный факторный эксперимент, который позволил вывести эмпирические уравнения, позволяющие учитывать пристенные эффекты при проектировании перерабатывающего оборудования без дополнительного проведения численных исследований. Разработаны конструкции экструзионных головок, позволяющих компенсировать влияние пульсаций расплава, которые возникают в результате действия пристенных эффектов, а также конструкция червяка экструдера, которая позволяет обеспечить поглощение пульсаций давления, возникающих в результате действия пристенных эффектов.
Soukup, Lubomír. "Analýza proudění v potrubí kruhového i nekruhového průřezu metodou využívající rozložení hustoty vířivosti po průřezu." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-256580.
Full textJegede, Olaseinde. "Dual-axis fluidic thrust vectoring of high-aspect ratio supersonic jets." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/dualaxis-fluidic-thrust-vectoring-of-highaspect-ratio-supersonic-jets(6d6a5867-8281-4dfd-ac45-105ff4e73e39).html.
Full textWong, William Chiu-Kit. "CFD Flame Spread Model Validation: Multi-Component Data Set Framework." Digital WPI, 2012. https://digitalcommons.wpi.edu/etd-theses/918.
Full textGoudot, Guillaume. "Applications innovantes des ultrasons en pathologie vasculaire : utilisation de l'imagerie ultrarapide dans l'analyse de la rigidité artérielle et des ultrasons pulsés en thérapie Arterial stiffening assessed by ultrafast ultrasound imaging gives new insight into arterial phenotype of vascular Ehlers–Danlos mouse models Aortic wall elastic properties in case of bicuspid aortic valve Segmental aortic stiffness in bicuspid aortic valve patients compared to first-degree relatives Wall shear stress measurement by ultrafast vector flow imaging for atherosclerotic carotid stenosis Pulsed cavitational therapy using high-frequency ultrasound for the treatment of deep vein thrombosis in an in vitro model of human blood clot." Thesis, Sorbonne Paris Cité, 2018. https://wo.app.u-paris.fr/cgi-bin/WebObjects/TheseWeb.woa/wa/show?t=2215&f=13951.
Full textLi, Ling [Verfasser], Puits Ronald [Akademischer Betreuer] Du, Jörg [Akademischer Betreuer] Schumacher, and Christoph [Akademischer Betreuer] Egbers. "Experimental investigation of the velocity and temperature fields near the walls in turbulent Rayleigh-Bénard convection / Ling Li. Betreuer: Ronald Du Puits. Gutachter: Jörg Schumacher ; Christoph Egbers." Ilmenau : Universitätsbibliothek Ilmenau, 2013. http://d-nb.info/1077774451/34.
Full textFaye, El Alioune. "Cisaillement pariétal et tourbillons en écoulement Taylor-Couette." Thesis, La Rochelle, 2013. http://www.theses.fr/2013LAROS393.
Full textThis work is an experimental study to highlight general mapping of the set of states obtained from the Couette laminar flow to turbulence. All experiments were performed in a device called Taylor-Couette system (TCS) which consists of two concentric cylinders with the inner cylinder rotating. The flow regimes (SPI, TVF, WVF, MWVF, TTVF), which depend mainly on the Taylor number (Ta), were obtained with or without axial flow in the TCS according to well-defined experimental protocols. We noted that the axial Reynolds number (Reax) has astabilizing effect on the flow. Using electrodiffusion method and analysis of films, the toroidal Taylor vortices, wavy or wavy modulated flow, were characterized in terms of the wall velocity gradients, wave number, axial and azimuthal wavelength, the axial velocity of vortex displacement, and there frequencies. The Taylor number has substantial effect on the evolution of these parameters in the investigated range. The use of three-segment electrodiffusion has contributed to the understanding of the mechanisms of vortex-wall interaction and the determination of the azimuthal and axial components of the wall velocity gradient
Vičan, Martin. "Modelování obrazů proudění." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226818.
Full textPerkins, Richard Mark. "PIV Measurements of Turbulent Flow in a Rectangular Channel over Superhydrophobic Surfaces with Riblets." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5547.
Full textAl-Faesly, Taofiq Qassim. "Extreme Hydrodynamic Loading on Near-Shore Structures." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34179.
Full textThuesen, Anna Helena, and Benjamin Lindahl. "Comparison of oxygen consumption while walking on treadmill wearing MBT Shoes versus Orthopedic Shoes : A treatise on shoe mass." Thesis, Hälsohögskolan, Högskolan i Jönköping, HHJ, Avd. för rehabilitering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-13695.
Full textTaan, Aly H. "A wall within a wall." Thesis, Virginia Polytechnic Institute and State University, 1990. http://hdl.handle.net/10919/53277.
Full textSaez, Manuel. "Contribution à l'étude expérimentale de la convection mixte." Université Joseph Fourier (Grenoble), 1998. http://www.theses.fr/1998GRE10197.
Full textMakin, Alexis David James. "Velocity memory." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/velocity-memory(c5c1c28d-0a23-44a5-93bc-21f993d2e7ad).html.
Full textSeligman, Joshua R. "Power development through low velocity isotonic, or combined low velocity isotonic-high velocity isokinetic training /." Thesis, University of Hawaii at Manoa, 2003. http://hdl.handle.net/10125/7046.
Full textBellec, Morgane. "Études du couplage entre turbulence et gradient de température pour l'intensification des transferts de chaleur dans les récepteurs solaires à haute température." Thesis, Perpignan, 2017. http://www.theses.fr/2017PERP0005/document.
Full textA promising line of research to increase the efficiency of solar tower power plants consists in heating pressurized air to high temperatures in order to fuel a Brayton thermodynamic cycle. This requires to design effective solar receivers that allow for intense heat transfers toward the fluid. To develop such receivers, an in-depth understanding of their internal flows is needed. These are complex flows, combining strong turbulence and strong temperature gradient between the concentrated sun irradiated wall and the back insulated wall.The aim of this work is to investigate numerically and experimentally such flows.On one hand, velocities are measured by SPIV (Stereoscopic Particle Image Velocimetry) in a turbulent channel flow wind tunnel whom measurement cell is similar to a surface solar receiver. The influence of an asymmetric heating on the turbulence statistics are especially investigated. These measurements are supplemented by Large Eddy Simulations run under the same conditions as the wind tunnel. Finally, a Large Eddy Simulation is run in a channel flow textured on one wall by an innovative geometry. This internal receiver design combines vortex generators and riblets in order to enhance the heat transfers
Stratmann, Jochen. "Droplet wall and spray wall interaction at increased ambient pressure and wall temperature." Aachen Shaker, 2009. http://d-nb.info/995684472/04.
Full textNordblad, Amanda. "Wall-Couture." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-692.
Full textBrunstorp, Jimmi. "Gallery Wall." Thesis, Konstfack, Inredningsarkitektur & Möbeldesign, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:konstfack:diva-4763.
Full textArrieta, Concha José Luis, and Huamán Glendha Falconí. "Video Wall." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2013. http://hdl.handle.net/10757/273539.
Full textSetright, E. Helen. "Moses Wall." Thesis, University of Leicester, 2003. http://hdl.handle.net/2381/30278.
Full textStratmann, Jochen [Verfasser]. "Droplet-Wall and Spray-Wall Interaction at Increased Ambient Pressure and Wall Temperature / Jochen Stratmann." Aachen : Shaker, 2009. http://d-nb.info/1159832323/34.
Full textKokkalis, Efstratios. "Fluid dynamic assessments of spiral flow induced by vascular grafts." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/5b96492f-983f-4baa-8e48-20da6939e65c.
Full textZhu, Weijia. "A new instrumentation for particle velocity and velocity related measurements under water /." View online ; access limited to URI, 2006. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/fullcit/3239913.
Full textBeg, Sarena. "The determinants of velocity." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq20781.pdf.
Full textSaeed, Khizer. "Laminar burning velocity measurements." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270733.
Full textKopp, Robert William. "Determination of the velocity." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/25837.
Full textTeng, Xiaoqing. "High velocity impact fracture." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32118.
Full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 315-330).
An in-depth understanding of dynamic ductile fracture is one of the most important steps to improve the survivability of critical structures such as the lost Twin Towers. In the present thesis, the macroscopic fracture modes and the fracture mechanisms of ductile structural components under high velocity impact are investigated numerically and theoretically. Attention is focused on the formation and propagation of through-thickness cracks, which is difficult to experimentally track down using currently available instruments. Studied are three typical and challenging types of impact problems: (i) rigid mass-to beam impact, (ii) the Taylor test, and (iii) dynamic compression tests on an axisymmetric hat specimen. Using an existing finite element code (ABAQUS/Explicit) implemented with the newly developed Bao-Wierzbicki's (BW) fracture criterion, a number of distinct failure modes including fragmentation, shear plugging, tensile tearing in rigid mass-to-beam impact, confined fracture, petalling, and shear cracking in the Taylor test, are successfully recreated for the first time in the open literature. All of the present predictions are in qualitative agreement with experimental observations.
(cont.) This investigation convincingly demonstrates the applicability of the BW's fracture criterion to high velocity impact problems and at the same time provides an insight into deficiencies of existing fracture loci. Besides void growth, the adiabatic shear banding is another basic failure mechanism often encountered in high velocity impact. This failure mechanism and subsequent fracture is studied through numerical simulation of a recently conducted compression test on a hat specimen. The periodical occurrence of hot spots in the propagating adiabatic shear bands is successfully captured. The relation between hot spots and crack formation is revealed. The numerical predictions correlate well with experimental results. An explicit expression controlling through-thickness crack growth is proposed and verified by performing an extensive parametric study in a wide range of input variables. Using this expression, a two-stage analytical model is formulated for shear plugging of a beam/plate impacted by a flat-nosed projectile. Obtained theoretical solutions are compared with experimental results published in the literature showing very good agreement.
(cont.) Three theoretical models for rigid mass-to-beam impact, the single, double, and multiple impact of beam-to-beam are derived from the momentum conservation principle. The obtained closed-form solutions, which are applicable to the axial stretching dominated case, are validated by finite element analysis.
by Xiaoqing Teng.
Ph.D.
Stober, Gunter, and Christoph Jacobi. "Meteor head velocity determination." Universität Leipzig, 2007. https://ul.qucosa.de/id/qucosa%3A15571.
Full textMeteors, penetrating the earths atmosphere, creating at high surface temperatures, which are caused by collisions with the surrounding air molecules, a several kilometer long plasma trail. The ionized plasma backscatters transmitted radar waves. This leads to characteristic oscillations, called Fresnel zones, at the receiver. The interference of these waves entails the typical signal shape of a underdense meteor with the sudden rise of the signal and the exponential decay. By means of a simulation the theoretical connection between velocity and signal shape is demonstrated. Furthermore it is presented, that the method from Baggaley et al. [1997] for determination of meteor entry velocities is applicable for a radar interferometer (SKiYMET). Finally the results are compared to other radar methods on similar equipment and to other experiments.
Johansson, Torneus Daniel, and Alexander Kotoglou. "Velocity of plasma flow." Thesis, KTH, Skolan för elektro- och systemteknik (EES), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-199363.
Full textStober, Gunter, and Christoph Jacobi. "Meteor head velocity determination." Universitätsbibliothek Leipzig, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-223206.
Full textMeteors, penetrating the earths atmosphere, creating at high surface temperatures, which are caused by collisions with the surrounding air molecules, a several kilometer long plasma trail. The ionized plasma backscatters transmitted radar waves. This leads to characteristic oscillations, called Fresnel zones, at the receiver. The interference of these waves entails the typical signal shape of a underdense meteor with the sudden rise of the signal and the exponential decay. By means of a simulation the theoretical connection between velocity and signal shape is demonstrated. Furthermore it is presented, that the method from Baggaley et al. [1997] for determination of meteor entry velocities is applicable for a radar interferometer (SKiYMET). Finally the results are compared to other radar methods on similar equipment and to other experiments
Widhe, Björn. "Chest wall sarcomas." Stockholm, 2010. http://diss.kib.ki.se/2010/978-91-7409-810-5/.
Full text