Bibliografías temáticas / Non-Hydrostatic Stresses

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Literatura académica sobre el tema "Non-Hydrostatic Stresses"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 8 de febrero de 2022

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Artículos de revistas sobre el tema "Non-Hydrostatic Stresses"

Guedda, H. Z., T. Ouahrani, A. Morales-García, R. Franco, M. A. Salvadó, P. Pertierra y J. M. Recio. "Computer simulations of 3C-SiC under hydrostatic and non-hydrostatic stresses". Physical Chemistry Chemical Physics 18, n.º 11 (2016): 8132–39. http://dx.doi.org/10.1039/c6cp00081a.

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Doe, T. W. y G. Boyce. "Orientation of hydraulic fractures in salt under hydrostatic and non-hydrostatic stresses". International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 26, n.º 6 (diciembre de 1989): 605–11. http://dx.doi.org/10.1016/0148-9062(89)91441-1.

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Wang, Xu y Peter Schiavone. "Coated non-elliptical harmonic inclusions with internal uniform hydrostatic stresses". International Journal of Engineering Science 63 (febrero de 2013): 30–39. http://dx.doi.org/10.1016/j.ijengsci.2012.11.003.

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Wang, Xu y Peter Schiavone. "Two non-elliptical decagonal quasicrystalline inclusions with internal uniform hydrostatic phonon stresses". ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik 98, n.º 11 (17 de septiembre de 2018): 2027–34. http://dx.doi.org/10.1002/zamm.201800106.

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Korotaev, Pavel, Pavel Pokatashkin y Aleksey Yanilkin. "The role of non-hydrostatic stresses in phase transitions in boron carbide". Computational Materials Science 121 (agosto de 2016): 106–12. http://dx.doi.org/10.1016/j.commatsci.2016.04.041.

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Wang, Xu y Peter Schiavone. "Internal uniform hydrostatic stresses in a three-phase non-elliptical inclusion subjected to a nearby concentrated couple". Mathematics and Mechanics of Solids 24, n.º 9 (29 de enero de 2019): 2931–43. http://dx.doi.org/10.1177/1081286519827059.

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We apply conformal mapping techniques with analytic continuation to study the existence of a uniform hydrostatic stress field inside a non-elliptical inclusion bonded to an infinite matrix via a finite thickness interphase layer when the matrix is simultaneously subjected to a concentrated couple as well as uniform remote in-plane stresses. We show that the desired internal uniform hydrostatic stress field is possible for given material and geometric parameters provided a certain constraint is placed on the remote loading. Subsequently, when the single loading parameter, five material parameters and three geometric parameters are prescribed, all of the unknown complex coefficients appearing in the series representing the corresponding conformal mapping function can be uniquely determined from a set of nonlinear recurrence relations. We find that the internal uniform hydrostatic stress field, the constant mean stress in the interphase layer and the hoop stress along the inner interface on the interphase layer side are all unaffected by the existence of the concentrated couple whereas the non-elliptical shape of the (three-phase) inclusion is attributed solely to the influence of the nearby concentrated couple.

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Zerihun, Yebegaeshet T. "A Numerical Study of Non-hydrostatic Shallow Flows in Open Channels". Archives of Hydro-Engineering and Environmental Mechanics 64, n.º 1 (27 de junio de 2017): 17–35. http://dx.doi.org/10.1515/heem-2017-0002.

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AbstractThe flow field of many practical open channel flow problems, e.g. flow over natural bed forms or hydraulic structures, is characterised by curved streamlines that result in a non-hydrostatic pressure distribution. The essential vertical details of such a flow field need to be accounted for, so as to be able to treat the complex transition between hydrostatic and non-hydrostatic flow regimes. Apparently, the shallow-water equations, which assume a mild longitudinal slope and negligible vertical acceleration, are inappropriate to analyse these types of problems. Besides, most of the current Boussinesq-type models do not consider the effects of turbulence. A novel approach, stemming from the vertical integration of the Reynolds-averaged Navier-Stokes equations, is applied herein to develop a non-hydrostatic model which includes terms accounting for the effective stresses arising from the turbulent characteristics of the flow. The feasibility of the proposed model is examined by simulating flow situations that involve non-hydrostatic pressure and/or nonuniform velocity distributions. The computational results for free-surface and bed pressure profiles exhibit good correlations with experimental data, demonstrating that the present model is capable of simulating the salient features of free-surface flows over sharply-curved overflow structures and rigid-bed dunes.

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Lazemi, Hossein Ali, Mohammad Fatehi Marji, Ali Reza Yarahmadi Bafghi y Kamran Goshtasbi. "Rock Failure Analysis of the Broken Zone Around a Circular Opening / Analiza pęknięcia skały w strefie naruszonej wokół otworu kolistego". Archives of Mining Sciences 58, n.º 1 (1 de marzo de 2013): 165–88. http://dx.doi.org/10.2478/amsc-2013-0012.

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In this paper, considering the non-linear Hoek-Brown failure criterion, a new theoretical model is presented to predict the stress components and estimate the plastic zone radius around a circular tunnel. The tunnel is excavated in an elasto-plastic rock mass subjected to plane hydrostatic and axial in situ stresses. Effects of the axial in situ stress on the plastic zone radius and stress components are studied. Based on the combination of plane hydrostatic and axial in situ stresses with the equilibrium equation and a suitable failure criterion (Hoek & Brown failure criterion), several cases are considered. For each case, the stress components, the plastic zone radius and the necessary conditions for its occurrence are determined. The results obtained by the present method are compared with those using Mohr-Coulomb criterion and with the experimental data, illustrating the validity of the present model in predicting the failure zone radius.

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Wu, Bisheng, Xi Zhang, Robert G. Jeffrey y Bailin Wu. "A semi-analytic solution of a wellbore in a non-isothermal low-permeability porous medium under non-hydrostatic stresses". International Journal of Solids and Structures 49, n.º 13 (junio de 2012): 1472–84. http://dx.doi.org/10.1016/j.ijsolstr.2012.02.035.

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Wang, Xu y Peter Schiavone. "Uniform hydrostatic stresses inside a coated non-parabolic inhomogeneity in the vicinity of a concentrated couple". International Journal of Solids and Structures 206 (diciembre de 2020): 23–29. http://dx.doi.org/10.1016/j.ijsolstr.2020.09.001.

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Más fuentes

Tesis sobre el tema "Non-Hydrostatic Stresses"

Guler, Erdogan. "A Methodology For Lining Design Of Circular Mine Shafts In Different Rock Masses". Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615662/index.pdf.

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The objective of this thesis is to predict lining thickness inside circular mine shafts. A numerical study with different rock mass strengths and different in-situ non-hydrostatic stresses are carried out in 2D shaft section models to predict pressures that develop on lining support. An iterative process of applying support pressure until observing no failure zone around shaft is used to simulate lining support pressure for each individual model. Later, regression and fuzzy logic analyses are carried out to find a pressure equation for all of the models. Finally, the pressure equation derived is used in elastic &ldquo
thick-walled cylinder&rdquo
equation to calculate the lining thickness required to prevent the development of a failure zone around shafts. At the end of this research, a computer program &ldquo
Shaft 2D&rdquo
is developed to simplify the lining thickness calculation process.

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Macgregor, Kenneth Waddell. "An investigation into the induced state of stress around inclined boreholes under non-hydrostatic stress conditions". Thesis, University of Strathclyde, 1987. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21493.

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This thesis details research conducted towards investigating the state of stress around inclined boreholes with the ultimate aim of predicting borehole stability and providing realistic estimates of closure stress. Chapter 1 discusses the factors affecting the stability of boreholes and reviews previous research conducted into borehole failure. The mechanics of hydraulic fracturing are reviewed as are methods of predicting fracture gradients. The manner in which closure stress is estimated is also critically reviewed. Chapter 2 describes an initial investigation into the stresses around inclined boreholes using the photoelastic technique of Stress Freezing. Chapter 3 details the laboratory determination of rock properties required for the borehole stability work detailed in Chapter 4. The applicability of the Brinell Hardness test to rock is also examined. Chapter 4 presents a detailed analysis of borehole stability. Failure criteria are developed and applied to estimate the mud weight required to maintain the hole in an elastic condition. To investigate the post-failure stability, existing 'yield zone' equations are modified to allow the effect of rock strength, oil flow rate, in-situ stress and hole angle to be examined. Chapter 5 describes the design and in-house manufacture of the specialised equipment required to measure fracture conductivity in the laboratory, the development of experimental procedures, the various test results and the conclusions drawn from them. Finally, the direct effect of a yield zone on the estimation of closure stress and on proppant selection is examined Chapter 6 summarises the conclusions that may be drawn from the work detailed in this thesis. The chapter also describes possible fields of future research which have been stimulated by the work presented. Two appendices are included, one providing a data-base of proppant properties, the other detailing the results of the application of the data-base to formation samples.

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Demenet, Jean-Luc. "Etude du silicium à basse et moyenne température sous forte contrainte : comportement des dislocations individuelles et plasticité". Poitiers, 1987. http://www.theses.fr/1987POIT2016.

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TSAI, LI-CHIEN y 蔡禮鍵. "Explicit Analyses of the Non-Linear Behavior of Rock Mass and Support System in Tunneling under Non-Hydrostatic Stress". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/31335705911025823239.

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碩士
中華大學
土木工程學系碩士班
99
ABSTRACT The simulation of behavior between rock mass and support system in tunneling is always to suppose the hypothesis that tunnel is under hydrostatic stress state (coefficient of lateral pressure Ko=1.0). Nevertheless, due to the variety of geological structure, the coefficient of lateral pressure has a great influence on the behavior of tunnel excavation. The purpose of this research is that the analytical solutions of nonlinear behavior of ground response curve and of support characteristic curve in a deep circular tunnel under hydrostatic stress state (Ko=1.0) and non-hydrostatic stress state (Ko≠1.0) are derived, and also consider the explicit analysis method which bases on the convergence confinement method for the Hoek-Brown failure criterion, the principle of convergence loss of equilibrium point, and effects of vertical stress, and the simple calculation spreadsheet is particularly proposed. The concept of explicit analysis method include that introducing a incremental procedure of confinement loss into the analytical solutions derived under non-hydrostatic stress state, establishing the direct calculation logic and flow chart, using a calculation spreadsheet to simply calculate and draw figures. The results obtained by the explicit analysis method (EAM) are compared with those by the finite element (FEM) program developed in this research. This comparison contains that consideration of inference factors (coefficient of lateral pressure, elastic limit of confinement loss and plastic radius, parameter of Mohr-Coulomb, confinement loss of non-supported distance, support stiffness of shotcrete, vertical stress, convergence loss of equilibrium point etc.); stress path, ground response curve, support characteristic curve, interaction curve at tunnel excavation surface, and distribution of stress-displacement around tunnel with unsupported and supported consideration, explored as a series of relatively. The influence factors of shotcrete consist of elastic modulus, Poisson ratio and thickness. The values of those parameters increase also increase that of the stiffness of shotcrete.In point of view of the parametric study of influence factors, the coefficient of lateral pressure is an important role that dominates the distribution of stresses and displacement around tunnel. The values calculated of elastic limit of convergence loss and the distribution of plastic radius are both influenced by the coefficient of lateral pressure. According to the results observed, it is shown that the comparison between EAM and FEM are almost coincident and has a good consistency under hydrostatic stress state. Concerning the vertical stress on the inclusion of non-hydrostatic stress conditions, in spite of the tunnel radial displacement has not been perfectly and correctly simulated in the reason of the different consideration of plastic potential function of strain. In addition, the results of EAM compared with those of FEM are shown a good consistency in Hoek-Brown and Mohr-Coulomb models. The explicit analysis method proposed in this research is an efficiency analysis method which could have a good simulation of non-linear behavior of ground response curve and of support characteristic curve in tunneling. Key words: Tunneling, Non-Hydrostatic Stress, Non-Linear, Failure Criterion, Convergence Confinement Method, Confinement Loss, Explicit Analysis, Finite Element Analysis

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Capítulos de libros sobre el tema "Non-Hydrostatic Stresses"

Batov, A., T. Gudkova y V. Zharkov. "Non-hydrostatic Stresses Under the Local Structures on Mars". En Springer Proceedings in Earth and Environmental Sciences, 229–37. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-97670-9_27.

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Li, X., Z. Wu, M. Takahashi y K. Yasuhara. "Hydrostatic and non-hydrostatic compressive stresses-induced permeability change in Kimachi sandstone". En Frontiers of Rock Mechanics and Sustainable Development in the 21st Century, 201–4. CRC Press, 2020. http://dx.doi.org/10.1201/9781003077510-45.

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Munis, James R. "Down But Not Out—Circulatory Arrest Pressures". En Just Enough Physiology, 70–76. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199797790.003.0009.

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Suppose that your heart has just stopped. What would happen to your blood pressure? At least 2 things would happen that you might not predict (and I hope you won't discover them anytime soon). First, the various blood pressures in the different parts of your circulatory system would converge to the same value. Second, you might be surprised to find that your blood pressure is not zero. That's not just because of vertical (hydrostatic) gradients within the body. Because the blood volume is considerably greater than the passive circulatory system volume, the blood vessels are slightly stretched and maintain a non-zero pressure even after the heart stops. To determine the actual non-zero pressure during cardiac arrest, we only have to divide the stressed blood volume by vascular compliance.

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Ampofo, Josephine y Michael Ngadi. "Novel Non-Thermal Processing Technologies: Impact on Food Phenolic Compounds during Processing". En Phenolic Compounds [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98688.

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In recent times, food consumption has advanced beyond simply meeting growth and development needs to include the supply of ingredients that can protect against diseases. Among such non-nutritive ingredients are phenolic compounds. These are benzene-ringed secondary metabolites produced in plants upon exposure to environmental stress. Previous studies have linked phenolic compounds to bioactive benefits (e.g., antioxidative, anti-inflammatory, and anti-cancer) with these bioactivities dependent on their biochemical structure and concentrations of individual phenolic compounds present in the food system. However, majority of plant foods are thermally processed into ready-to-eat forms, with these processing methods potentially altering the structure and subsequent bioactivities of endogenous phenolic compounds. Thus, the aim of this chapter is to highlight on emerging non-thermal novel technologies (such as pulsed electric field, radiation, ultrasonication, high hydrostatic pressure processing and high pressure carbon dioxide processing) that can be exploited by the food industry to preserve/enhance bioactivities of phenolic compounds during processing.

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Kraus, Eric B. y Joost A. Businger. "Atmospherically Forced Perturbations in the Oceans". En Atmosphere-Ocean Interaction. Oxford University Press, 1995. http://dx.doi.org/10.1093/oso/9780195066180.003.0011.

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Kinetic energy flows almost exclusively downward, from the atmosphere into the ocean. The upward flux of energy is thermal, and that will be the topic of our concluding chapter. In the present chapter, we shall deal with the effects of kinetic energy inputs into the ocean. Although this requires some discussion of the different types of oceanic perturbations, our treatment of these topics is necessarily brief and incomplete. We are not concerned with details of the motion pattern in the deeper ocean or with processes involving friction and non-adiabatic mixing in the interior. These processes are essential for an understanding of ocean circulations. They are treated in general oceanographic textbooks and in many monographs that deal specifically with these subjects. Surface stress and air pressure variations produce surface wind waves along with a variety of other wave forms. Most of these waves are relatively slow, with periods that can be measured in hours, days, or even years. The amplitude of internal gravity waves in the oceans is often much larger than that of surface waves and their wavelengths tend to be in the kilometer range. The square of the amplitude-wavenumber product is usually a very small quantity. This makes first order approximations appropriate for many purposes. It justifies use of the hydrostatic approximation and of the linear equations as a basis for the following discussion. To do so, it is necessary to represent the unspecified forcing terms on the right-hand side of those equations in a linearized form. An algorithm for the inclusion of the various atmospheric inputs as a linearized boundary condition in the equations of motion for the ocean is discussed in Section 7.1. Section 7.2 describes a two-layer ocean model. Systems of this type are convenient for the conceptual consideration of atmosphere-ocean interactions, because the wind affects the ocean primarily through action upon the surface mixed-layer. Internal waves, the topic of Section 7.3, are ubiquitous both in the ocean and in the atmosphere. Essentially, sea surface gravity waves can be viewed as internal waves at the interface between two fluids of very unequal density.

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Actas de conferencias sobre el tema "Non-Hydrostatic Stresses"

Pan, J. "Mixed Mode I/III Crack-Tip Fields for Perfectly Plastic Mises Materials". En ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/pvp2007-26392.

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In this paper, governing equations and solutions for asymptotic singular and non-singular crack-tip sectors in perfectly plastic Mises materials are first reviewed under combined in-plane and out-of-plane shear loading conditions. The crack-tip fields under mixed mode I/III loading conditions are then investigated. One assembly of four crack-tip plastic sectors is adopted with stress discontinuities along the border of two constant stress sectors. The solutions of the crack-tip fields under pure mode I and mixed mode I/III loading conditions are presented. The crack-tip fields under pure mode I and mixed mode I/III loading conditions give fully-plastic solutions with various hydrostatic tensile stresses ahead of the crack tip. The characteristics of the mode I limits of fully plastic crack-tip fields with different hydrostatic tensile stresses ahead of the crack tip agree well the past computational results under pure mode I with different constraint conditions.

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Nakamura, Yuichi, Masanori Shimaoka, Yutaka Ishibashi y Masahito Matsui. "Plastic Deformations of Micro-Spheres by Solidified Lubricants and Lubricants’ Shear Stress Under Very High Pressure". En World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63099.

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In order to grasp the possibility of evaluating shear properties for solidified lubricants under high pressure, plastic deformations of metal micro-spheres (about 0.07mm) in solidified lubricants were evaluated by employing a diamond-anvil pressure cell (DAC). Large deformations (2–5 times larger than the original sphere dimensions) were observed for CVT oil and ester oil up to 6 GPa at 23–25°C. Deformation starting pressure agreed with the solidified pressure. These deformations were caused by the non-hydrostatic pressure in the solidified lubricants. Shear stresses of the solidified lubricants were tentatively and roughly estimated from the plastic deformations of the spheres based on some assumptions. They almost agreed with the mean shear stress (traction force / hertzian contact area) from traction test.

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Dankowski, Hendrik y Charlott Weltzien. "Calculation of the Hydrostatic and Structural Integrity of Docking Sequences". En ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61368.

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The conditions of competition within ship yards are changing. The current market situation requires a new orientation of the Pella Sietas ship yard with flexible solutions for new ship types. Complex, heavy and ice-going ships show one way for future designs. In view of all the technical difficulties involved in such challenging projects, the first question must be how to handle these heavy constructions with the yards building facilities available. The Pella Sietas yard is using a floating platform for newbuildings. The question arises whether or not this platform is still capable and suited for this kind of ship types. The docking procedure is a complex multi-body interaction that copes with hydrostatic and structural challenges. The docking operation is regulated by the sequence of flooding and emptying ballast water tanks of the dock. At any time of this dynamic operation the hydrostatic stable equilibrium of ship and dock must be ensured. When the ship becomes afloat the keel block system transfers the ships weight on the structure of the dock. It must be ensured that the resulting tensions and deformations do not exceed the maximum permissible values. This paper describes a fast calculation method that determines the mentioned hydrostatic as well as the structural investigations during the docking procedures. The method implies a numerical progressive flooding simulation that calculates the hydrostatics of ship and dock under consideration of their interaction by dock blocks together with the ballasting sequence in the time domain. Furthermore it calculates the block forces distribution by applying the deformation method. In the calculation process ship and dock are modeled as Timoshenko beams and the dock blocks as non-linear spring elements. Moreover the shear force and bending moment distributions of ship and dock are calculated and the deflection lines are presented. Therefore, the described method enables the ship yard to evaluate quickly the possibility of building new types of ships on the existing building platform and allows evaluating which modifications are useful to enlarge the capacity of the platform even further. It provides a useful tool to minimize local and global stresses and deformations of the interacting bodies during the whole docking procedure by fast optimization of the block system arrangement and the ballasting sequences. As a result the described method could expand the range of flexibility of a given floating dock structure. In addition, the whole hydrostatic and structural integrity of docking sequences can be computed faster and more accurate even at a very early project stage.

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Prioul, Romain y Thomas Lebrat. "Calibration of velocity‐stress relationships under hydrostatic stress for their use under non‐hydrostatic stress conditions". En SEG Technical Program Expanded Abstracts 2004. Society of Exploration Geophysicists, 2004. http://dx.doi.org/10.1190/1.1851153.

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Vega, Sandra, Manika Prasad y Gary Mavko. "Comparative study of velocities under hydrostatic and non‐hydrostatic stress in sands". En SEG Technical Program Expanded Abstracts 2003. Society of Exploration Geophysicists, 2003. http://dx.doi.org/10.1190/1.1817504.

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Fontanabona, Julien, Ky Dang Van, Vincent Gaffard, Zied Moumni y Paul Wiet. "Prevention of Pipeline Dent Failure Under Fatigue Loading Conditions". En 2014 10th International Pipeline Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/ipc2014-33199.

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Pipeline dents fatigue life prediction is a subject of high interest for pipelines operating companies. Empreinte is an in-house developed pre and post processor to ABAQUS Finite Element Calculations dedicated to pipeline integrity assessment. Empreinte was first developed and experimentally validated for dents assessments under static loading conditions. As oil but also gas transmission pipelines are submitted to cyclic loading conditions (internal pressure variations, shutdowns, temperature variations …), it was decided to introduce a fatigue life criterion in Empreinte based on the Dang Van theory assuming that local mesoscopic stresses drive fatigue crack initiation. Full scale tests performed for PRCI projects PR-201-927, PR-201-9324 and MD-4-2 were used to validate the proposed fatigue assessment methodology: - the first full scale fatigue test was performed in 1994 on an X52 pipe. For this test, limited material and test data were available. - the second full scale fatigue test was performed in 2007 on an X52 pipe. For this test, material characterization (in particular tensile tests with full stress strain curves) and test data (strain gages measurements, indenter geometry …) were available. Fatigue life assessments were performed following three main steps: 1. using available data: non linear kinematic hardening constitutive laws were identified for the two pipes materials; 2. finite elements elastic-plastic modeling of the denting processes were carried out; 3. fatigue calculations were performed following a new approach using Dang Van criterion for which the parameters were determined from literature data. The elastic shakedown assumption allowed the determination of the local stress cycle from the macroscopic stress cycle. The fatigue criterion integrating the combined influences of shear and hydrostatic stresses was checked on all points of the pipe. Good agreement between experimental and calculated fatigue lives and fatigue crack initiation points was reached. This opens a promising way to assess pipeline defects fatigue life. Efforts are now focused on the standardization of a testing method to identify the Dang Van criterion of a pipeline material at least in air environment.

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Wiersma, B. J. y J. B. Elder. "Structural Impact Assessment of Flaws Detected During Ultrasonic Examination of a Radioactive Waste Tank". En ASME 2003 Pressure Vessels and Piping Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/pvp2003-2037.

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Ultrasonic (UT) inspection of an underground storage tank containing radioactive waste was conducted at the Savannah River Site (SRS). Ten cracks were identified during this examination. A critical review of the information describing stress corrosion crack behavior for the SRS waste tanks, as well as a summary review of the service history this tank, was performed. Each crack was then evaluated for service exposure history, consistency of the crack behavior with the current understanding of stress corrosion cracking, and present and future impact to the structural integrity of the tank. In all cases, the crack behavior was determined to be consistent with the previous understanding of stress corrosion cracking in the SRS waste tank environment. The length of the cracks was limited due to the short-range nature of the residual stresses near seam, repair and attachment welds. In many cases the cracks were associated with exposure to fresh waste from the SRS canyons as previously observed. However, cases in which the crack was observed to go through-wall while located in the vapor space above the waste were also observed. The time of initiation and propagation rate of these cracks is unknown. A re-examination of these cracks will determine whether these cracks are continuing to grow while in the vapor space. The impact of these cracks on the future service of this tank was also assessed. A bounding loading condition due waste removal of the sludge at the bottom of Tank 15 was considered for this analysis. The analysis showed that the combination of hydrostatic and weld residual stresses do not drive any of the cracks identified during the UT inspection to instability. For all cracks the instability length was more than 10 times the actual flaw length. The re-examination of this tank is scheduled for 2007. This examination would provide information to determine whether any additional detectable degradation is occurring and to supplement the basis for specification of conditions that are non-aggressive to tank corrosion damage for similar tanks at SRS.

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Baud, Sébastien y Philippe Velex. "Static and Dynamic Tooth Loading in Spur and Helical Geared Systems: Experiments and Code Validation". En ASME 2000 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/detc2000/ptg-14435.

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Abstract The primary objective of this study is to validate a specific finite element code aimed at simulated dynamic tooth loading in geared rotor systems. Experiments have been conducted on a high-precision single stage spur and helical gear reducer with flexible shafts mounted on hydrostatic or hydrodynamic bearings. The numerical model is based on classical elements (shaft, lumped stiffnesses, ...) and on an original gear element which accounts for non-linear time-varying mesh stiffness, gear errors and tooth shape modifications. External and parametric excitations are derived from the instantaneous contact conditions between the mating flanks by using an iterative contact algorithm inserted in a time-step integration scheme. In a first step, experimental and numerical results at low speeds are compared and it is demonstrated that the proposed tooth mesh interface model is valid. Comparisons are then extended to dynamic fillet stresses on both spur and helical gears between 50–6000 rpm on pinion shaft. Despite a localized problem in the case of spur gears with one particular bearing arrangement, the broad agreement between the experimental and numerical response curves proves that the model is representative of the dynamic behavior of geared systems.

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Scrivner, Ron, Butch Exley y Chris Alexander. "Girth Weld Failure in a Large Diameter Gas Transmission Pipeline". En 2010 8th International Pipeline Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ipc2010-31525.

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There have been several recent weld failures either during the initial post construction hydrostatic tests, or immediately following construction. Girth welds typically do not fail as a result of internal hoop loads without the contribution of loads due to out side forces. External loading should be considered during design, welding procedure development, construction, and pipeline operations. This paper presents one example where a girth weld failed as a result of preexisting 1940’s weld imperfections and recent, 1980’s, external loading. This analysis of the girth weld failure in the 30-inch pipeline included an initial failure analysis, a fracture mechanics analysis, and a finite element analysis that integrated the pipe-soil interaction, as well as localized stresses associated with weld imperfections. A critical part of this study was to evaluate how changes in soil conditions associated with a drought followed by soil saturation associated with rainfall, contributed to lack of local support and increased overburden loads associated with the saturated soil. The failure analysis of the ruptured girth weld and surrounding pipe concluded that the failure of the girth weld was caused by increased bending loads imposed on the pipeline after recent construction activities, and that the fracture initiated at a lack-of-penetration/fusion imperfection that was 20 1/4-inches long and 0.110 inches deep. A coupled investigation using finite element and fracture mechanics analyses verified numerically that with reduced-strength soil, stresses were generated in the girth weld of sufficient magnitude to cause a fracture. Temperature, terrain, and fatigue were considered, but were not deemed to significant enough to affect the stresses or other conditions that resulted in the failure. The overriding observation of this study is that no single factor contributed to the failure that occurred. Rather, the girth weld failure was the result of weld imperfections that generated elevated stresses due to excessive loads imparted to the pipe due to settlement associated with non-compact backfill associated with excavation work. Had the pipe not displaced vertically due to localized soil conditions, it is unlikely that the pipeline would have failed. The recent excavation activities were adequate for normal soil conditions; however, dry soil at the time of construction resulted in lack of compaction and excessive moisture just prior to the failure that generated in differential settlement and heavy overburden, combined with lack of penetration imperfection in the girth weld in question, resulted in generating excessive bending stresses that contributed to the eventual failure of the pipeline.

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Keaney, G. M. J., P. G. Meredith y S. A. F. Murrell. "Laboratory Study of Permeability Evolution in a Tight' Sandstone under Non-Hydrostatic Stress Conditions". En SPE/ISRM Rock Mechanics in Petroleum Engineering. Society of Petroleum Engineers, 1998. http://dx.doi.org/10.2118/47265-ms.

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