Дисертації з теми "Crack in pipe"
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Genussov, Ron M. S. "Rapid crack propagation in pipe grades of poly-ethylene." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47444.
Повний текст джерелаBeheshti, Milad. "Fatigue life prediction of threaded pipe connection." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/15588.
Повний текст джерелаWheel, Marcus A. "High speed double torsion testing of pipe grade polyethylenes." Thesis, Imperial College London, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318493.
Повний текст джерелаArgyrakis, Christos. "Models for designing pipe-grade polyethylenes to resist rapid crack propagation." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5564.
Повний текст джерелаAyyer, Ravishankar. "Failure Processes in Polymers: Environmental Stress Crack Growth and Adhesion of Elastomeric Copolymers to Polypropylene." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1243608270.
Повний текст джерелаTitle from PDF (viewed on 19 August 2009) Department of Macromolecular Science and Engineering Includes abstract Includes bibliographical references Available online via the OhioLINK ETD Center
Hazra, Sumit Kumar. "Crazing and yielding in polyethylene under impact." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369223.
Повний текст джерелаIngham, Edward John. "The development of impact toughness and resistance to slow crack growth in modified polyvinyl chloride and polyethylene pipe grade polymers." Thesis, Manchester Metropolitan University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271274.
Повний текст джерелаArun, Sutham. "Finite element modelling of fracture & damage in austenitic stainless steel in nuclear power plant." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/finite-element-modelling-of-fracture-and-damage-in-austenitic-stainless-steel-in-nuclear-power-plant(031e5ceb-b3b5-4499-8094-dbe362e27ff7).html.
Повний текст джерелаYayla, Pasa. "Rapid crack propagation in polyethylene gas pipes." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/8711.
Повний текст джерелаSantos, Elielson Alves dos. "Resistência à fadiga de tubo API 5L X65 cladeado e soldado circunferencialmente com eletrodos de Inconel® 625." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-08062016-084524/.
Повний текст джерелаRecent oil and gas discoveries in the Pre-Salt layer represent a huge exploration potential in Brazil, however, the technological challenges for the exploitation of these mineral resources are immense and therefore have motivated the development of studies looking for efficient methods and materials for their productions. The oil and gas pipellines, called risers, are elements that are necessarily welded and have fundamental importance in the production chain, since they transport oil and natural gas from the sea bed to the platforms and are subject to dynamic loads (fatigue) during operation. Additionally, one of the central problems in the production of oil and gas in the Pre-Salt reserves is directly associated with a highly corrosive media, such as H2S and CO2. A cheaper way to protect the pipelines from these medias is applying a protective layer of a corrosion resistant metal on the inner diameter of these pipes, creating a cladded pipe. Thus, a joining process of these pipes to form the risers must be carried out by the use of girth welds with a corrosion resistance material similar to the clad metal. As the welded structures are seen as potential location of \"crack like\" defects, to ensure the structural integrity of such component when subjected to repetitive loading conditions, it is necessary to know the fatigue crack growth rates for the girth weld. Therefore, in this work it was carried out fatigue crack propagation tests in the weld region of an API 5L X65 cladded pipe with Inconel® 625, girth welded using Inconel® 625 electrodes. From the welded region, Single Edge Notch Bending specimens, SEN(B), were removed with different thickness and width ratios (B/W= 0.5, 1, and 2). From the fatigue tests, the crack propagation rates (da/dN) as function of the variation of the stress intensity factor (ΔK), were determined for the weld metal, using different crack size measurement techniques: the elastic compliance (EC), electric potential drop (EPD) and image analysis (IA). The results showed that the different B/W ratios used in study did not modified significantly the fatigue crack growth rates, considering that crack propagation took place under small scale yielding conditions. The results of fatigue crack growth tests allowed to obtain the regions I and II of da/dN x ΔK curves for the weld metal. The ΔKth value obtained for the weld metal was around 11,8 MPa.m1/2 and the found values of the experimental constants C and m of Paris-Erdogan\'s equation were respectively equal to 1,55 x10-10 [(mm/cycle)/( MPa.m1/2)m] and 4.15. The micromechanism of fatigue crack growth took place by plastic deformation, with the formation of fatigue striations.
Венгринюк, Т. П. "Розроблення ізоляційно-композитного покриття для підвищення міцності нафтогазопроводів з тривалим терміном експлуатації". Thesis, Івано-Франківський національний технічний університет нафти і газу, 2013. http://elar.nung.edu.ua/handle/123456789/4435.
Повний текст джерелаВ диссертации предложено новое изоляционно-защитное покрытие, а также методы и средства его нанесения, с целью совмещения противокоррозионной защиты нефтегазопроводов с повышением их сопротивления механическому разрушению, в том числе на стадии роста коротких усталостных трещин. Разработано изоляционно-композитное покрытие на основании эпоксидной смолы, армированное стеклотканью, назначенное для изоляции нефтегазопроводов диаметром 500 - 720 мм класса А и класса Б, которое отличается высокими термостойкостью, прочностью, адгезией к стальным трубам, изоляционными и противокоррозионными свойствами. Решена задача создания способа предупреждения развития трещиноподобных и коррозионных дефектов поверхности трубопроводов путем применения нового, разработанного автором состава многокомпонентного композитного покрытия и способа его нанесения. Способ обеспечивает высокую технологичность и простоту нанесения покрытия, поскольку монтаж данных покрытий не нуждается в достижении особенных контролируемых параметров, таких как очистка поверхности труб до металлического блеска и нагревание до определенной температуры. Способ эффективен в условиях, когда нагревание трубы при нанесении изоляции недопустимо. Защитное покрытие, которое получают согласно данному способу для защиты труб от повреждений, отмечается термостойкостью, прочностью, высокой адгезией к стальным трубам, высокими изоляционными и противокоррозионными свойствами. Ударная прочность полученного покрытия составляет 15 Дж, что отвечает усиленному покрытию класса В. Установлены особенности роста коротких усталостных трещин в стали 17Г1С газопровода и выявлено, что длительная эксплуатация незначительно уменьшила циклическую трещиностойкость стали при пульсирующем цикле нагрузки, но с ее повышением прогнозируется увеличение отрицательного влияния эксплуатации. По значениям порогового размаха коэффициента интенсивности напряжений вычислена граница усталости металла з короткими трещинами. Для нагрузки, близкой к пульсирующей, наблюдается увеличение границы усталости в узком диапазоне коротких трещин, что обусловлено эффектом закрытия трещин. Длительная эксплуатация газопровода проявилась в снижении границы усталости металла. Разработан способ повышения сопротивления распространению коротких усталостных трещин в трубных сталях нанесением на трубопровод под давлением текучей составляющей разработанного изоляционно-композиционного покрытия, что искусственно создает эффект закрытия трещин после ее затвердевания, чем совмещается противокоррозионная защита з повышением циклической трещиностойкости металла. Исследовано напряженное состояние стального трубопровода, покрытого трехслойным композиционным покрытием и определено, что оно незначительно уменьшает напряжения в бездефектной трубе, но ощутимо в трубе с трещиной. Определено концентрацию напряжений возле поверхностной трещины в трубе с покрытием при различных значениях ремонтного давления. Установлено, что разработанное покрытие уменьшает за счет навитой стеклопластиковой ленты напряжения в бездефектной трубе на 4,5 % и на 2,3 % соответственно при ррем=0 и при ррем=0,5р, а также уменьшает коэффициент интенсивности напряжений в окрестности вершины трещины на 12...25 %. Разработана конструкция автоматизированного устройства для намотки полимерно-композиционного бандажа на трубу с автоматизированным регулированием необходимого натяжения, плотностью прилегания к поверхности, необходимой толщиной намотки нахлесткой смежных витков, что позволяет достигать высокой прочности адгезионных покрытий с поверхностью металла.
The new isolative coating and the methods and facilities for its covering are proposed in the dissertation, with a goal of a combination of oil and gas pipelines anticorro-sion protection and an increase of its resistance to mechanical fracture, including on the stage of short fatigue crack growth. The isolative-composition coating is developed on the base of epoxy resin, reinforced by glass-fabric, which is distinguished by high thermal resistance, strength, adhesion with steel pipes and anticorrosion properties The peculiarities of short fatigue crack growth in gas pipeline 17G1S steel are established ant it is revealed that long-term service of the pipeline decreased slightly fatigue crack growth resistance of the steel at the pulsatile load asymmetry but the negative influence of service is predicted to be increase with a rise of asymmetry. The method of an increase of fatigue short crack growth resistance in pipe steels by a deposit of the fluid component of the isolative coating what creates artificial crack closure effect and it combines anticorrosion protection with an increase of fatigue crack growth resistance of metal. Stress state of steel pipeline, covered by three layers composite coating, is investigated and it is established that it decreases slightly stresses in defectless pipe but noticeably in pipe with crack.
Molteno, Matthew Robert. "Eddy current detection of fatigue cracks in drill pipes." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/6084.
Повний текст джерелаIncludes bibliographical references.
The Vertical Marine Mining technique is a lucrative method used by De Beers to recover bottom lying diamonds from the seabed, mainly off the coast of Namibia. The method employs a 200m length pipe-drilling structure rotated from the surface and acting as a conduit through which the disturbed sediment is transported to the surface for processing. However, cyclic operating stresses combined with corrosion have tended to cause circumferential fatigue cracks to develop on the outside surface of the drill pipe and propagate inwards. As no early warning system exists, these cracks propagate undetected until failure occurs. High operational costs and losses associated with down time, provide a strong motivation for a system to detect fatigue cracking prior to failure, especially given that fatigue crack growth rate and fatigue lifetimes can be estimated using Fracture Mechanics principles. Therefore what is required is an early warning of fatigue crack initiation with non-destructive testing (NOT). The eddy current method is an ideal NDT technique as it does not require contact with the test surface and is highly sensitive to fatigue cracks .. However, this method is generally only sensitive to surface and near surface defects. This proves to be a major limitation - the external drill pipe surface is obstructed by flanges and fittings such that continuous inspection of the external surface would be impossible. Therefore two specialised eddy current methods to allow the detection of external fatigue cracks from inside the drill pipe were reviewed, namely: Pulsed Eddy Current (PEC) and Remote Field Eddy Current (RFEC). It was found that unlike PEC, RFEC is highly sensitive to external circumferential planar defects in ferrous pipes. This, above all, highlighted the suitability of RFEC for drill pipe inspection.
Pandya, Kedar Chaitanya. "The study of long term fracture properties in tough polyethylene." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.344082.
Повний текст джерелаSsozi, Eva Nantongo. "The effect of viscoelastic deformation in pipe cracks on leakage response to variations in pressure." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13263.
Повний текст джерелаWater is an important and increasingly scarce resource in the world today. Unfortunately, a lot of water is lost through leakage since most distribution systems are deteriorating. Therefore research in leakage management is necessary in order to improve the utilization of water resources. Leakage may be reduced by managing the water pressure in water distribution systems. One of the important factors affecting the pressure-leakage relationship is pipe material behaviour (Van Zyl & Clayton 2007; Greyvenstein & Van Zyl 2007). The pressure – leakage relationship has been described by several relationships such as the Torricelli equation, the Fixed and Variable Area Discharge (FAVAD) concept and the conventional equation. Pipe material behaviour affects leakage parameters in the pressure-leakage relationship such as the leak area and the leak exponent (Cassa et al. 2010). For this project, the pressure-leakage relationships in High Density Polyethylene (HDPE) and Polyvinylchloride (PVC) pipes are investigated. HDPE and PVC are polymeric materials and therefore exhibit a viscoelastic response to applied stress and applied strain. Viscoelastic responses include creep, relaxation, hysteresis and time dependency. When these pipes experience stresses due to water pressures, failure and fracture may occur as leaks. The viscoelastic properties of these materials therefore affect how the leaks respond to pressure change. The effect of viscoelastic deformations in leaks was investigated using Finite Element Analysis (FEA) software, Abaqus. Round holes and longitudinal cracks were represented as individual leaks in HDPE and PVC pipes in Abaqus. Pressure was applied to each pipe model for different time periods, and the deformed leak areas were obtained. Further analysis was carried out to determine the effects of pressure on leak parameters such as the gradient of the leak area-pressure relationship, leak exponent and the leakage number. The analysis shows that viscoelastic deformations have an effect on the pressure-leakage relationship. A linear relationship exists between the leak area and pressure for all time periods investigated and therefore gradients could be obtained. Deformed leak areas, gradients and leak exponents all increased with time and therefore confirmed that the time dependency of viscoelastic materials affected the pressure-leakage relationship. The leakage exponents for both materials were found to vary between 0.5 and 1.5 for both HDPE and PVC. HDPE also exhibited higher leak exponents, gradients and larger deformed leak areas than PVC for the same leaks. It was also found that leakage in viscoelastic materials may be analysed using the leakage number, developed for elastically deforming materials by Van Zyl & Cassa (2013).
Chan, Che Wan. "The ultrasonic nondestructive evaluation of welds in plastic pipes." Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/7208.
Повний текст джерелаОриняк, Андрій Ігорович. "Методи розрахунку коефіцієнта інтенсивності напружень з врахуванням геометричної нелінійності та довільної форми тріщини". Doctoral thesis, Київ, 2021. https://ela.kpi.ua/handle/123456789/43758.
Повний текст джерелаThe dissertation is dedicated to the development of numerical and analytical methods for calculating the stress intensity factor (SIF) for nonclassical problems of fracture mechanics, in particular, for cracks of complex shape and for cracks in thin structures with taking into account geometric nonlinearity (GN) and their applications in various industries, in particular, for nuclear power plants, for calculation of the elements of the reactor unit. A modification of Williams's method is presented, which describes the stress state in the crack tip. For modification of the classical approach in the considered method the additional members were presented, which are infinite in the crack tip, but attenuate at infinity. The main idea of the method is to divide the whole area of the body into two separate parts – internal one, which embraces the tip of the crack, and the external one. In the inner area, only the classic Williams functions are used, and in the outer area both the classical members and additional ones are used. At the boundary between the selected subdomains, the conjugation conditions are to be fulfilled, the essence of which is to equalize here the stresses and displacements. The very high efficiency of this method is shown for bodies that have the shape of a circle, or are infinite, where almost exact values (up to 6-7 digits) are achieved when using no more than 12-16 members of the expansion. However, for a very elongated rectangular body the method gives much worse results, and the error can reach up to 2%. The practical significance of the proposed approach consists in the obtaining the simple and effective tool for testing the capabilities of commercial packages for calculating the parameters of fracture mechanics, which, as we know, do not always provide the correct results for case when load is applied on the crack surfaces. A thin-walled pipe with a long surface crack is considered. The pipe, surface of which may contain the initial deviation form ideal circle, is loaded by inner pressure. In first time the problem of determining the SIF was considered in a geometrically nonlinear formulation, when changes in the geometry of the body in the process of deformation are accounted for linear material behavior. Based on the Chen-Finnie method, which considers the crack as concentrated compliance, and on original solution for geometrically nonlinear behavior of curved initially distorted beam, the compact analytical formulas are obtained, which gives the value of SIF for each value of inner pressure. Comparison of the analytical results with those obtained by careful numerical FEM analysis, on the one hand, showed their good correspondence, and therefore the accuracy and efficiency of both the analytical and numerical procedures are confirmed. On the other hand, for the first time in the scientific literature, the value of SIF in a geometrically nonlinear formulation are obtained for surface cracks in slightly distorted cylindrical shell with surface long crack. It was shown that even for perfectly circular pipes having the cracks with depth up to half of the thickness of pipe walls, loaded by moderate level of inner pressure, the geometrical nonlinear values of SIF can be 10-15% less than those at linear approach application. This is very significant practical result. Another geometrically nonlinear problem is numerically investigated by known commercial FEM software for the through crack, which is loaded by a significant value of additional longitudinal force (the main factor of geometric nonlinearity considered) and small value of internal pressure (linear consideration). This statement distinguished this task from research conducted at NASA (USA), where the pressure and axial force were proportional as to pipe with closed ends. The geometric nonlinearity of the study is investigated through an incremental increase in loads and the corresponding recalculation of the SIF for the already taken into account changes in the deformed geometry (curvature). A number of tasks for determining the SIF for different pipe radii and dimensionless force values were calculated. Dimensionless parameters, which characterize the deviation of the values of SIF from the linear one, are numerically determined. Application of least square method allowed to suggest the simplified analytical formula for calculation of these deviations. These results are of great theoretical and practical importance. In particular, it is shown that for real pipes the neglecting by influence of axial force in usual approach may lead to 4-6% error of SIF determination. It is noted that additional account for large values of pressure, possible plastic deformations, may further reduce the actual values of SIF. Thus, the significance of the problems and the need for further research in this direction are shown. The necessity of analysis of flat cracks of non-canonical shape in three-dimensional bodies is noted. This is due to the fact that almost all existing solutions in the literature and reference results in normative documents are given for cracks that have shape of an ellipse or its part. However, real cracks detected by non-destructive testing are irregularly shaped cracks. Therefore, it is necessary to create the analytical methods that would allow to assess the impact of the crack shape, and to verify them with careful numerical procedures by FEM. For this purpose, flat internal cracks in infinite 3D body are considered. The formulation of problems for them is reduced to well-known integro-differential equation of the theory of elasticity. Note, that exact fundamental analytical solutions of which exist only for a circular crack and only for some simple laws of loading for an elliptic crack. A universal semi-analytical method for solving the integro-differential equation of the theory of elasticity for plane cracks of normal separation of arbitrary shape has been developed. It is proposed to consider the displacement of the crack edges as a product of a certain function of the crack shape, which satisfy to known asymptotic behavior of the displacement field near the crack front, and a certain polynomial series. As for the functions of the form, three variants of their choice were investigated - a) classical, which depends on the squares of ratio of radial coordinate of the considered point, and the corresponding coordinate of contour point; b) multiplicative, based on the product of equations describing the straight sections of the crack contour, and c) the original Oore-Burns function, which is an integral of the crack contour from the inverse square of the distance of the considered point to each point of the contour. The results showed that the greatest accuracy is achieved by application of hypersingular approach with Oore-Burns function of form. The verification of results was performed for elliptic crack, semielliptic inner crack, rectangular crack. The results were compared with numerical ones calculated by FEM. Practical calculations of SIF dependance with time for NPP reactor ant its elements for different scenarios of emergency situations are carried out. A number of simulation models with a built-in crack have been created, for which SIF calculations were performed by nonlinear FEM analysis. For cracks going through the cladding, where stress jumps occur, the method of influence functions is elaborated, and analytical-numerical procedure used piece-wise continuous basic laws of loading. Practical calculations were performed for the nozzle of reactor vessel, the cylindrical part of vessel, the core barrel and core baffle. These calculations were used to justify the extension of the service life of several units of Ukrainian NPPs.
Диссертационная работа посвящена разработке численных и аналитических методов расчета коэффициента интенсивности напряжений, (КИН) для неклассических проблем механики разрушения, в частности, для трещин сложной формы и для трещин в тонкостенных конструкциях с учетом геометрической нелинейности, (ГН). Представлена модификация метода Вильямса, что учитывает затухающие на бесконечности члены. Исследованы границы и даны рекомендации о применении данного метода. Разработан аналитический метод расчета КИН в трубах с длинными осевыми поверхностными трещинами с учетом ГН в зависимости от внутреннего давления. Результаты хорошо коррелируют с полученными в роботе численными решениями МКЭ. Построены численные модели для расчета КИН и раскрытия берегов трещин в ГН постановке для сквозных трещин в зависимости от переменной величины осевой силы. Построена апроксимационная формула, что описывает влияние ГН эффекта для обобщенной осевой силы и безразмерной длины трещины. Показана значимость эффекта для реальных лабораторных экспериментов. Разработан универсальный полуаналитический метод решения интегро-дифференциального уравнения теории упругости для плоских трещин нормального отрыва произвольной формы. Для проверки аналитических результатов построены численные модели МКЭ для трещин разной формы, например, для прямоугольной, внутренней полуэллиптической трещины, и др., и проведено сопоставление результатов. Проведены практические расчеты КИН во времени для элементов конструкций АЭС для разных сценариев прохождения аварийных ситуаций. Для этого создан ряд имитационных моделей со встроенной трещиной, для которой расчеты КИН проводили методами нелинейной механики разрушения. Для трещин, что проходят через наплавленный материал, где происходят скачки напряжений, обосновано применение метода функций влияния, для чего разработано аналитико-численную процедуру, что использует частично непрерывные базовые законы нагружения.
Tidström, Lina. "Estimation of Probabilities of Detection for Cracks in Pipes in Swedish Nuclear Power Plants." Thesis, Uppsala University, Department of Mathematics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-121427.
Повний текст джерелаFiedler, Lubomír. "Lomové chování trubkových polyolefinů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233956.
Повний текст джерелаZhang, Xiangping. "Characterization of filament wound GRP pipes under lateral quasi-static and low velocity impact loads." Thesis, University of Aberdeen, 1998. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU551705.
Повний текст джерелаParise, Luís Fernando Schiano. "Fully plastic J and CTOD estimation procedure for circumferential surface cracks in biaxially loaded pipes." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-14122014-171536/.
Повний текст джерелаO objetivo principal deste trabalho é o desenvolvimento de um procedimento para estimação das forças motrizes e CTOD para trincas circumferenciais superficiais em dutos submetidos a carregamento combinado de flexão e pressão interna. Pretende-se que a metodologia aqui proposta seja aplicável a uma ampla faixa de geometrias de duto e trinca, características de escoamento e encruamento de material e níveis de biaxialidade de carregamento. Em particular, dutos atualmente empregados na exploração submarina de óleo e gás constituem uma classe importante de aplicações em potencial para procedimentos dessa natureza. Por essa razão, a avaliação de integridade estrutural de dutos pressurizados submetidos a enrolamento em carretel serve como tema motivador e ponto de conexão com a aplicação real ao longo deste trabalho. A base teórica fundamental sobre a qual se assentam os desenvolvimentos aqui propostos é o procedimento de estimação de forças motrizes de trinca conhecido como metodologia EPRI. Este método tradicional de cálculo de e CTOD separa as forças motrizes em componentes elástica e plástica. A component elástica é calculada diretamente a partir de soluções para o fator de intensidade de tensões, que se encontram amplamente disponíveis. A componente plástica, por sua vez, é determinada a partir de soluções totalmente plásticas derivadas de um modelo de lei de potência para o comportamento do material. Na primeira parte deste trabalho a metodologia EPRI em sua forma tradicional é estendida para abranger os casos de interesse, permitindo assim a determinação de e CTOD para trincas circumferenciais superficiais em dutos carregados por flexão e pressão interna. Para isto empregam-se simulações computacionais por elementos finitos, os resultados das quais permitem a determinação direta de fatores adimensionais que correlacionam (CTOD) com o carregamento aplicado de maneira consistente com as soluções totalmente plásticas da metodologia EPRI original. Na segunda parte do trabalho a atenção se volta para algumas deficiências e limitações da metodologia desenvolvida na primeira parte. Um procedimento novo é proposto como alternativa, tendo por objetivo superar estas dificuldades a partir da combinação dos principais conceitos da metodologia EPRI com ideias derivadas do projeto baseado em deformações. Apresentam-se a base teórica subjacente à estes conceitos e a derivação analítica do novo procedimento de estimação de forças motrizes. Finalmente, resultados semelhantes aos obtidos na primeira parte são calculados e os dois procedimentos são comparados. Embora ambos sejam conceitualmente equivalentes, argumenta-se que o procedimento baseado em deformações é mais imediata e convenientemente aplicado a algumas classes importantes de problemas práticos. O trabalho encerra com comentários acerca dos efeitos de biaxialidade de carregamento sobre as forças motrizes de trinca e com discussões sobre a acurácia, relevância, e significância física das funções adimensionais que escalam as forças motrizes com cargas ou deformações.
Yavas, Ozgur. "Effect Of Welding Parameters On The Susceptibility To Hydrogen Cracking In Line Pipe Steels In Sour Environments." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12608074/index.pdf.
Повний текст джерелаKhademi, Zahedi Reza [Verfasser], Timon [Akademischer Betreuer] Rabczuk, Roham [Gutachter] Rafiee, and Wahab Magd [Gutachter] Abdel. "Stress Distribution in Buried Defective PE Pipes and Crack Propagation in Nanosheets / Reza Khademi Zahedi ; Gutachter: Roham Rafiee, Magd Abdel Wahab ; Betreuer: Timon Rabczuk." Weimar : Bauhaus-Universität Weimar, 2021. http://d-nb.info/1238522076/34.
Повний текст джерелаVaziri, Mojgan. "Water Resistance of Scots Pine Joints Produced by Linear Friction Welding." Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10059/document.
Повний текст джерелаWood welding is a mechanical friction process allowing the assembly of timber without any adhesives. The process consists of applying mechanical friction, under pressure, alternately to the two wood surfaces to be welded. This process can be applied to weld two flat pieces of timber, originating from the same or different tree species, and can be used in the manufacture of furniture and wood joinery. The only limitation is that the joint is not exterior-grade, but only suitable for interior joints. Exterior use, or use in an environment with varying humidity demands water resistance of the welded joints. The main objective of this thesis is to study the water resistance of the welded wood. This is complemented with special attention to non-destructive test methods such as X-ray Computed Tomography (CT-) scanning and Magnetic Resolution Imaging (MRI). The influence of welding parameters and wood properties on crack formation and crack propagation in the weldline was investigated. The influence of these parameters on weldline density and water absorption in the weldline were also studied. Investigations in this thesis are based on welded samples of Scots pine (Pinus sylvestris) of the dimensions 200 mm × 20 mm × 40 mm which were cut in the longitudinal direction of the wood grain. The tensile-shear strength of the welded Scots pine samples were determined using European standard EN 205. Different non-destructive methods such as X-ray Computed Tomography (CT-) scanning to study crack formation and propagation, and magnetic Resolution Imaging (MRI) to characterize water penetration and the distribution mechanism in welded wood were used. Solid state CPMAS 13C NMR spectrometry and X-ray microdensitometry investigations were carried out to study the mechanism of adhesion in Scots pine. These various non-destructive methods offer the advantage of non-invasive analysis and the elimination of any artifacts present due to preparation and sectioning. The most important results are summarized as follows: (1) X-ray Computed Tomography (CT-) scanning and Magnetic Resolution Imaging (MRI) are versatile research methods applicable to investigations of welded woods. (2) Water resistance of welded Scots pine can be increased using heartwood, a welding pressure of 1.3 MPa, and a welding time of 1.5 s. (3) Optimization tests showed that the tensile-shear strength of Scots pine was more sensitive to welding time changes than holding time and could be optimized to more than 9.7 MPa using 1.3 MPa welding pressure, > 3.5 s welding time, and < 60 s holding time. (4) Changing welding parameters and wood properties can increase water resistance of welded wood to some extent, but treating the weldline with certain natural and environmentally-friendly water repellents is still necessary. (5) Welded Scots pine shows unusually high water resistance and tensile-shear strength. This may be explained by there being more extractives compounds in Scots pine. (6) MRI experiments showed that the origin of the joint failure in welded beech is poor water resistance of the weldline, while swelling and shrinkage of wood are the main reasons for joint failure of welded Scots pine. (7) Extractives in Scots pine dramatically improve water resistance of the welded joint, but not to a level to classify the joint as an unprotected exterior grade. However, it can qualify as a joint for protected semi-exterior application
Scalet, Giulia. "L'effetto della pressione sulle perdite in condotte con fessure longitudinali - The effect of pressure on leakage in longitudinally crecked pressurized pipes." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2010. http://amslaurea.unibo.it/1503/.
Повний текст джерелаDao, Ngoc Ha. "Modélisation de la fatigue des systèmes de forage de puits à trajectoire complexe." Thesis, Paris, ENMP, 2014. http://www.theses.fr/2014ENMP0004/document.
Повний текст джерелаFacing the growing complexity of trajectories and operating conditions of oil and geothermal drillings, the fatigue phenomenon has become the main cause of drill-string failure. The fatigue of drill-pipes is essentially due to their cyclic bending caused by their rotation in a curved section of the well. The objective of this work is to develop a methodology and the necessary numerical models to assess the fatigue of drill-pipes during drilling operations of complex trajectory wells. For this purpose, we propose firstly to choose among the available approaches for structure fatigue life prediction those that seem most relevant to drill-string fatigue problem. Then, these approaches (which include the fatigue and fracture theories as well as empirical laws), and structural calculation software are then integrated into incremental computation algorithms of drill-pipe fatigue in function of drilling operation evolution. Since the stresses in drill-pipes remain often within the elastic domain, two fatigue models for drill-pipes are developed: the first one is based on the cumulative fatigue calculation and the second one on the fatigue crack growth calculation. These models can be used in the well and drill-string design, or in real time during drilling to predict the fatigue failure in the drill-string. This allows the drill operator to plan the management of drill-pipes and their inspections depending on their usage history
Mikula, Jakub. "Lomové chování svařovaných polyolefinových trubek." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231097.
Повний текст джерелаPoduška, Jan. "Vliv reziduálních napětí na odhad životnosti polymerních trubek." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-399209.
Повний текст джерелаCUNTO, GABRIEL G. de. "Aplicação do conceito "vazamento antes da falha" (LEAK BEFORE BREAK) em tubulações de aço 316LN soldado com metal de adição 316L." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/27963.
Повний текст джерелаMade available in DSpace on 2017-11-01T17:02:12Z (GMT). No. of bitstreams: 0
Este trabalho apresenta um estudo prático da aplicação do conceito Leak Before Break (LBB), usualmente aplicado em usinas nucleares, em uma tubulação fabricada a partir de aço AISI 316LN soldada com a utilização de eletrodo revestido AISI 316L. O LBB é um critério fundamentado em análises de mecânica da fratura, que considera que um vazamento proveniente de uma trinca, presente em uma tubulação, possa ser detectado por sistemas de detecção de vazamento, antes que esta trinca alcance um tamanho crítico que implique na falha da tubulação. Na tubulação estudada, foram realizados ensaios mecânicos de tração e análises de Ramberg-Osgood, bem como ensaios de tenacidade à fratura para a obtenção da curva de resistência J-R do material. Os ensaios foram realizados considerando o metal base, a solda e a zona termicamente afetada (ZTA), nas temperaturas de operação de uma planta nuclear. Para as propriedades mecânicas encontradas nos ensaios foram realizadas análises de carga limite para se determinar o tamanho da trinca que cause um vazamento detectável e, também, o seu tamanho crítico que cause a falha por colapso plástico. Para o tamanho crítico de trinca encontrado na solda, região que apresentou a menor tenacidade, foram realizadas análises de Integral J e de módulo de rasgamento T, considerando falha por rasgamento dúctil. Os resultados demonstram um comportamento bem definido entre o metal base, a ZTA e a solda, onde o metal base apresenta um comportamento altamente tenaz, a solda um comportamento pouco tenaz e a ZTA apresentou propriedades mecânicas intermediárias entre o metal base e a solda. Utilizando o software PICEP, foram determinadas as curvas de taxa de vazamento versus tamanho de trinca e também o tamanho crítico da trinca, considerando análise por carga limite. Observou-se que, após certo tamanho de trinca, a taxa de vazamento do metal base é muito maior do que para a ZTA e solda, para um mesmo comprimento de trinca. Isso ocorre porque é esperado que a trinca cresça de forma mais arredondada no metal base, devido à sua maior tenacidade. O menor tamanho crítico de trinca foi encontrado para o metal base para trincas circunferenciais. Para as análises de Integral J realizadas na solda, foi demonstrado que a falha por rasgamento dúctil não ocorrerá nas condições consideradas e essa hipótese foi sedimentada pela análise de mecânica da fratura elasto-plástica (MFEL) com o uso do diagrama J/T. Dessa forma, pode-se concluir que a tubulação estudada estaria apta a ser empregada em um circuito primário de um reator que utilizasse o critério de LBB, nas condições de carregamento e geometria consideradas. Adicionalmente, concluiu-se que nessas condições apenas o modo de falha por colapso plástico é esperado.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
Luky, Robin. "Predikce creepového poškození polymerních trubek." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230310.
Повний текст джерелаGuidara, Mohamed Amine. "Analyse des conditions de rupture des conduites d’adduction d’eau potable en polyéthylène, sous l’effet d’écoulement transitoire, en présence d’un défaut." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0042/document.
Повний текст джерелаThe efficiency of potable water distribution systems has been recently the subject of much research. Leakages or a ruptures, occurring in pipes, are quite a frequent phenomenon in urban areas. In order to minimize long-term risks of leakage, about 60% of potable water networks are built or renewed with the third generation of polyethylene pipe, PE100. It is a material with various features, which makes it a widely used material in the water supply networks. However, under transient conditions and with a surficial defect in the pipe, a failure occurs. To investigate this issue, our study is divided into two main parts. The first part is studying the dynamic effect of the viscoelastic material under transient flow conditions using a developed mathematical model. We have demonstrated that the viscoelastic behavior of PE100 plays a primordial role in the damping of water hammer and resonance phenomenon. In case of presence of coupling junction, a study of the fluid structure interaction is mandatory to correctly define the natural frequencies of a piping system. In the second part, we have investigated the crack behavior of PE100 pipes with defects. Using the experimental tests and finite elements results, we have demonstrated that the concept of elastic-plastic fracture mechanics, the J-Integral, define with reasonable accuracy the behavior of cracked PE100-pipe. At the end, we sought to determine the J-Integral with a semi-empirical model in order to define a relationship between the crack initiation pressure, the dimension of semi-elliptical surface cracks and the geometry of the pipe
Fruasaha, Petronilla A. "Regulation of Calcium Entry Pathway in Jurkat T Cells." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1231558093.
Повний текст джерелаRoudný, Tomáš. "Statické řešení věžového vodojemu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265366.
Повний текст джерелаHagos, Bereket Abrha. "Microstructural and chemical behaviour of irradiated graphite waste under repository conditions." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/microstructural-and-chemical-behaviour-of-irradiated-graphite-waste-under-repository-conditions(45b519ef-2f67-4aca-9b92-94a975e12875).html.
Повний текст джерелаBaghalian, Amin. "Detecting Structural Defects Using Novel Smart Sensory and Sensor-less Approaches." FIU Digital Commons, 2017. https://digitalcommons.fiu.edu/etd/3560.
Повний текст джерелаRuber, Lukáš. "Nosná železobetonová konstrukce bytového domu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372062.
Повний текст джерелаIvsins, Andrew Kristofer. ""Got a pipe?": the social dimensions and functions of crack pipe sharing among crack users in Victoria, BC." Thesis, 2010. http://hdl.handle.net/1828/3044.
Повний текст джерелаCAI, JIA-ZHANG, and 蔡佳璋. "Instability analysis on the circumferential crack of a ductile pipe." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/34950173177540552800.
Повний текст джерелаMiao, Chuxiong. "A support vector machine model for pipe crack size classification." Master's thesis, 2009. http://hdl.handle.net/10048/400.
Повний текст джерелаTitle from pdf file main screen (viewed on July 16, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Mechanical Engineering, University of Alberta." Includes bibliographical references.
Marvasti, Mohammad Hassan. "Crack growth behavior of pipeline steels in near neutral pH soil environment." Master's thesis, 2010. http://hdl.handle.net/10048/1065.
Повний текст джерелаMaterials Engineering
Yang, Yanjun. "Nondestructive Evaluation of the Depth of Cracks in Concrete Plates Using Surface Waves." Thesis, 2009. http://hdl.handle.net/10012/4314.
Повний текст джерелаChen, Shih-Jeng, and 陳世徵. "Mechanical Analysis and Design of Structural Pipes with Crack." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/62168010347918133127.
Повний текст джерела淡江大學
機械工程學系
87
Title of Thesis: Page: 107 Mechanical Analysis and Design of Structural Pipes with Crack Name of Institute: Graduate Institute of Mechanical Engineering, TamKang University Graduate Date: July, 1999 Degree Conferred: Master Name of Student: Shih-Jeng Chen Advisor: C.J.Shih 陳 世 徵 Abstract: A statically indeterminated structural pipe with crack in this thesis has been used as the analytical and design problem. The mathematical model of the mechanics has been built up to analyze the mechanical behavior of the failure. To analyze the cracked- pipes deformation due to earthquake,the limit analysis theory and elastic-plastic fracture mechanics are combined to obtain the relation between the torsional angle-deformation and cracked angle-deformation under crack propagation,The analy-tical process and result allows one to understand the plastic collapse behavior of the structural pipe with crack. For improving the character of loading ability due to ductil unstable fracture,the J-R curve theory has been adopted tostudy the dJ/da which is the key factor of crack. Further more, the character of ductil unstable fracture can be applied to findthe critical dJ/da. For estimating the time required along the crack propagation,the stress corrosion cracking theory has been applied to compute the life estimation from the crack propagation tocollapse of pipe. The equation of collapsed load and deformation are used as constraints of optimal design. The goals are the minimization of volume and dJ/da value. Not only the structural fracture can be successfully analyzed,but also this presented optimization method can improve the crack behavior.
Chen, Jen-Shiung, and 陳振雄. "On the Identification of Cracks Existing in a Pipe by dc-pd Technique." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/63608811139866912817.
Повний текст джерела國立清華大學
動力機械工程學系
88
Based on the dc-pd (direct-current-potential-drop) technique, an efficient detection procedure is developed to identify the existence of unknown cracks in a pipe. By this procedure, the electric potential on the perfect pipe needs to be calculated first by finite element method. The proposed defect influence factor, which is defined as the electric potential of the defective pipe divided by that of the perfect one, is then employed to reveal the effect of unknown cracks on the electric potential. By depicting the constant contours of the defect influence factor with sufficient resolution, not only the position, but also the shape and size of cracks in the pipe can be identified accurately by the detection criterion devised in this work. Those cracks detected include circumferential crack, inclined crack, and multiple cracks. Good identified results show the merits of the procedure developed for the identification of unknown cracks in the pipe structure.
Buckley, Richard Steven. "Theoretical investigation and experimentation into the expansion of round holes and cracks within pressurised pipes." Thesis, 2008. http://hdl.handle.net/10210/409.
Повний текст джерелаProf. K. van Zyl
Cassa, Amanda Marilu. "A numerical investigation into the behaviour of cracks in uPVC pipes under pressure." Thesis, 2012. http://hdl.handle.net/10210/5255.
Повний текст джерелаThis study is a numerical investigation into the behaviour of cracks in uPVC pipes under pressure. This study is a continuation of a Masters dissertation which showed that leakage exponents vary significantly from the theoretical orifice exponent of 0.5 for cracks in pipes for different materials. This study looks at the behaviour of cracks in more detail and specifically with regard to the parameters of the pipe and crack. Using Finite Element Analysis the relationship between the pressure head and the leak area in pipes with longitudinal, spiral and circumferential cracks was investigated. It was found that the longitudinal, spiral and circumferential crack areas increase linearly with pressure. The slope of this linear relationship depends on various parameters, including loading state, pipe dimensions and pipe material properties. The effect that the individual pipe parameters had on the pressure-area slope was investigated. These parameters included the material properties of the pipe (Young’s modulus, Poisson’s ratio and longitudinal stress), the geometry of the pipe (internal diameter and wall thickness) as well as the geometry of the crack (length of the crack and the width of the crack). Once the effect of the pressure-area slope m is known, the link between the conventional leakage exponent N1 and the pressure-area slope m was further investigated and the effect of each parameter on the leakage exponent N1 was found. Using various data techniques the above data was combined and processed to find mathematical relationships that give reasonable descriptions of the pressure-area slopes of longitudinal, spiral and circumferential cracks. Once these equations for the pressure-area slopes were determined it was possible to obtain three new relationships for leakage from longitudinal, spiral and circumferential cracks.
LIU, CHENG-CHIEN, and 劉政傑. "Numerical Simulation of Fatigue Growth of Cracks in the Inner Surface of a Pipe Elbow." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/jt4y94.
Повний текст джерела國立虎尾科技大學
飛機工程系航空與電子科技碩士班
106
When a pipeline is subjected to a periodic loading for a long period of time, cracks initiated on the inner wall of the pipeline may cause safety concern, which is important when cracks occur in the region near pipe elbow where stress distribution is rather complex. This paper studies the impact of the bent angle of a pipe elbow and the location of a crack in crack growth process. The finite element method is used to analyze different elliptical cracks in a curved pipe wall, and to solve stress intensity factors and energy release rates of elliptical cracks. The cracks are assumed to keep in elliptic shape when they propagate. Two different crack growth models are studied in the present work: the constant crack growth rate mode and the non-constant crack growth rate mode. The length of the long axis and the short axis of the elliptic crack increases with the same amount every computational step in the former mode. In the latter mode, the crack of the short axis advances at a preset propagation rate, therefore, fixed crack length increase every step, and the crack length increase of the long axis is determined by the crack propagation rate, which depends on the local stress intensity factors. The behaviors of stress intensity factors, energy release rates and fatigue loading cycles of cracks were investigated under the constant crack growth rate mode and the non-constant crack growth rate mode. The results show that the stress intensity factor is larger when the position angle of crack is smaller, i.e. outer side of the pipe elbow with smaller curvature. When the pipe elbow bends, the stress intensity factor will increase until the bent angle reaches about 15 degree, after which the stress intensity factors reduces a little and the level up. Therefore, it can be concluded that the fracture position angle is minimal and the elbow bending angle is easily affected by the crack at 15 degrees. In both crack growth modes, stress intensity factors and energy release rates of the initial long axis are smaller than that of the short axis, however, the variation of the stress intensity factors and energy release rates of the long axis is larger than those of the short axis, and the stress intensity factors and the energy release rates of the long axis increase at faster rates than that of the short axis. In the constant crack growth rate model, the long axis and the short axis of crack are fixed at length 0.1mm. Under the two crack growth modes, the initial aspect ratio of two axes has little effect on the fatigue cycle life of the long axis. The short axis will have a shorter fatigue cycle life as the initial short axis ratio is smaller. In the non-constant crack growth rate mode, the crack length of the long and short axes of the elliptic crack has a direct effect on the local stress intensity factors, which cause the crack growth rates of the crack at different location are different along the crack front. However, as the crack advances, the elliptic aspect ratio of the crack will approaches to 0.88 under the present study.
Iranpour, Mohammad. "FATIGUE CHARACTERIZATION OF RISERS AND PIPELINES UNDER REALISTIC VARIABLE AMPLITUDE LOADING AND THE INFLUENCE OF COMPRESSIVE STRESS CYCLES." Thesis, 2013. http://hdl.handle.net/10222/50472.
Повний текст джерела