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Littérature scientifique sur le sujet « Elastic lifetime »

Auteur : Grafiati

Publié le 9 mars 2023

Mis à jour le 11 mars 2023

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Articles de revues sur le sujet "Elastic lifetime"

Parker, A. P., S. N. Endersby, T. J. Bond, J. H. Underwood, S. L. Lee et J. Higgins. « Stress Concentration, Stress Intensity, and Fatigue Lifetime Calculations in Autofrettaged Tubes Containing Axial Perforations Within the Wall ». Journal of Pressure Vessel Technology 119, n^o 4 (1 novembre 1997) : 488–93. http://dx.doi.org/10.1115/1.2842334.

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Elastic, elastic-plastic and experimental stress analyses, and fatigue lifetime predictions are presented for thick cylinders containing multiple, axial holes within the wall. The holes are generally semi-elliptical (including semi-circular), and the cylinders are autofrettaged after introduction of the holes and are subsequently subjected to cyclic pressurization of the bore. Two potentially critical failure locations are identified; a fracture-mechanics based design methodology is proposed; elastic and elastic-plastic finite element (FE) analyses are undertaken. The elastic FE analysis predicts hoop stresses at the bore resulting from internal pressurization which are some 7 percent higher than those for the equivalent plain tube. For a given hole size and location and for nominal overstrains of 40 percent or greater, the residual compressive stress at the bore is reduced by approximately 15 percent below the value for a plain tube of the same radius ratio. Two experimental investigations are reported, one based upon X-ray diffraction, to measure residual stresses and stress gradients, and the other based upon radial tube slitting, to measure opening angle. They confirm most features of the residual stress profiles predicted from FE analysis with the exception of high compressive residual stresses and stress gradients immediately adjacent to the hole boundaries. Appropriate use of the residual stress information permits prediction of tube lifetimes for cracks emanating from the bore and from the hole. For the geometry and loading under consideration, the more critical location is predicted to be the hole boundary, the lifetime for failures originating from this point being some 60 percent of the lifetime for cracks originating at the bore.

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Pazdera, Lubos, Libor Topolar, Jaroslav Smutny et Kristyna Timcakova. « Nondestructive Testing of Advanced Concrete Structure during Lifetime ». Advances in Materials Science and Engineering 2015 (2015) : 1–5. http://dx.doi.org/10.1155/2015/286469.

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The paper reports on measurements and analysis of the measurements during hardening and drying of specimens using selected acoustic nondestructive testing techniques. An integrated approach was created for better understanding of the relations between the lifetime cycle and the development of the mechanical properties of concrete. Acoustic emission, impact echo, and ultrasonic techniques were applied simultaneously to the same mixtures. These techniques and results are presented on alkali-activated slag mortars. The acoustic emission method detects transient elastic waves within the material, caused by the release of cumulated stress energy, which can be mechanical, thermal, or chemical. Hence, the cause is a phenomenon which releases elastic energy into the material, which then spreads in the form of an elastic wave. The impact echo method is based on physical laws of elastic stress wave propagation in solids generated by mechanical impulse. Ultrasonic testing is commonly used to find flaws in materials or to assess wave velocity spreading.

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Kansy, J., T. Suzuki, T. Ogawa et M. Murakami. « Study of poly(methylphenylsilylenemethylene) by elastic thermalization lifetime analysis ». Radiation Physics and Chemistry 58, n^o 5-6 (juin 2000) : 545–50. http://dx.doi.org/10.1016/s0969-806x(00)00215-2.

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Kondrashov, Oleg V., Timur R. Galimzyanov, Rodion J. Molotkovsky, Oleg V. Batishchev et Sergey A. Akimov. « Membrane-Mediated Lateral Interactions Regulate the Lifetime of Gramicidin Channels ». Membranes 10, n^o 12 (25 novembre 2020) : 368. http://dx.doi.org/10.3390/membranes10120368.

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The lipid matrix of cellular membranes is an elastic liquid crystalline medium. Its deformations regulate the functionality and interactions of membrane proteins,f membrane-bound peptides, lipid and protein-lipid domains. Gramicidin A (gA) is a peptide, which incorporates into membrane leaflets as a monomer and may form a transmembrane dimer. In both configurations, gA deforms the membrane. The transmembrane dimer of gA is a cation-selective ion channel. Its electrical response strongly depends on the elastic properties of the membrane. The gA monomer and dimer deform the membrane differently; therefore, the elastic energy contributes to the activation barriers of the dimerization and dissociation of the conducting state. It is shown experimentally that channel characteristics alter if gA molecules have been located in the vicinity of the conducting dimer. Here, based on the theory of elasticity of lipid membranes, we developed a quantitative theoretical model which allows explaining experimentally observed phenomena under conditions of high surface density of gA or its analogues, i.e., in the regime of strong lateral interactions of gA molecules, mediated by elastic deformations of the membrane. The model would be useful for the analysis and prediction of the gA electrical response in various experimental conditions. This potentially widens the possible applications of gA as a convenient molecular sensor of membrane elasticity.

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P, Contreras. « A Tale of the Scattering Lifetime and the Mean Free Path ». Physical Science & ; Biophysics Journal 6, n^o 2 (12 octobre 2022) : 1–12. http://dx.doi.org/10.23880/psbj-16000225.

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The idea of applying the scattering lifetime calculated from the imaginary part of the zero temperature elastic scattering cross-section to study a hidden self-consistent damping in two spaces of importance for non-equilibrium statistical mechanics is proposed. It is discussed its relation with the classical phase space from statistical mechanics and the configuration space from nonrelativistic quantum mechanics. This idea is contrasted with the mean free path values in three elastic collision regimes. The main exercise is to study the behavior of a self-consistent probabilistic distribution function in a space we have called the reduced phase space since it is related to the scattering lifetime. This exercise has been solved in two unconventional superconductors for which several calculations are discussed. One of them is to obtain the scattering phase shift from the inverse strength of an atomic potential and the other is to build several phases with different nodal configuration of the superconducting order parameter and show that the imaginary self-consistent part of the scattering cross-section is always positive for two compounds: the triplet strontium ruthenate and the singlet doped with strontium lanthanum cuprate when three models of superconducting order parameters are used: the quasi-point, the point and the line nodal cases. We finally compare the frequency dispersion in the anomalous skin effect with singular shapes of the Fermi surface with the frequency dispersion in the scattering lifetime and their respective mean free paths. This idea is useful because it intuitively explores the nonlocality of this type of hidden self-consistent damping for those incoherent fermionic quasiparticles.

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Guo, Shiwen, et Jie Yan. « Structural-Elastic Determination of the Lifetime of Biomolecules Under Force ». Biophysical Journal 114, n^o 3 (février 2018) : 577a. http://dx.doi.org/10.1016/j.bpj.2017.11.3155.

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Song, Ming Xin, Rui Wu, Qian Liu, Hong Wang, Zuo Bao Cao, Ming Hua Chen et Jing Hua Yin. « Reliability Research of Capacitive RF-MEMS Switch ». Advanced Materials Research 753-755 (août 2013) : 2507–10. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.2507.

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This paper presents the model of capacitive RF-MEMS switch for the lifetime prediction. The model is based on dielectric charging failure mechanism. The simulation results show that lifetime can reach 1000 hours when elastic coefficient (K) adopts 4-16N/m, Si3N4 as dielectric material, 0.4-1μm of dielectric thickness, 2-5μm of plate distance, less than 20V of driven voltage.

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Qian, Jin, Jizeng Wang et Huajian Gao. « Lifetime and Strength of Adhesive Molecular Bond Clusters between Elastic Media† ». Langmuir 24, n^o 4 (février 2008) : 1262–70. http://dx.doi.org/10.1021/la702401b.

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Parker, A. P., J. H. Underwood et D. P. Kendall. « Bauschinger Effect Design Procedures for Autofrettaged Tubes Including Material Removal and Sachs’ Method ». Journal of Pressure Vessel Technology 121, n^o 4 (1 novembre 1999) : 430–37. http://dx.doi.org/10.1115/1.2883726.

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Autofrettage is used to introduce advantageous residual stresses into pressure vessels and to enhance their fatigue lifetimes. The Bauschinger effect serves to reduce the yield strength in compression as a result of prior tensile plastic overload and can produce lower compressive residual hoop stresses near the bore than are predicted by “ideal” autofrettage solutions (elastic/perfectly plastic without Bauschinger effect). A complete analysis procedure is presented which encompasses representation of elastic-plastic uniaxial loading material behavior and of reverse-loading material behavior as a function of plastic strain during loading. Such data are then combined with some yield criterion to accurately predict elastic-plastic residual stress fields within an autofrettaged thick cylinder. Pressure for subsequent reyielding of the tube is calculated. The numerical procedure is further used to determine residual stress fields after removal of material from inside diameter (i.d.) and/or outside diameter (o.d.), including the effects of any further plasticity. A specific material removal sequence is recommended. It is shown that Sachs’ experimental method, which involves removing material from the i.d., may very significantly overestimate autofrettage residual stresses near the bore. Stress ranges and stress intensity factors for cracks within such stress fields are calculated together with the associated fatigue lifetimes as such cracks propagate under cyclic pressurization. The loss of fatigue lifetime resulting from the Bauschinger effect is shown to be extremely significant.

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Shlyannikov, Valery, Ivan Ishtyryakov et Rustam Yarullin. « Life-time prediction for aviation GTE compressor disk based on mixed-mode and multi-axial fracture resistance parameters ». MATEC Web of Conferences 300 (2019) : 11001. http://dx.doi.org/10.1051/matecconf/201930011001.

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This study is concerned with analysis of fatigue crack growth and life-time prediction for aviation GTE compressor disk under operation conditions. For consideration were different combinations of rotational speed, temperature, surface flaw form and sizes as well as elastic-plastic titanium alloy BT3-1 properties are employed. A crack growth rate equation is derived involving the fracture process zone size and nonlinear stress intensity factor. The assessments of the structural integrity of the rotating disk are compared for elastic and elastic-plastic solutions. It is stated that the traditional elastic crack growth models overestimate the residual fatigue lifetime with respect to the nonlinear fracture mechanics approach.

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Thèses sur le sujet "Elastic lifetime"

Swinteck, Nichlas Z. « Phase-Space Properties of Two-Dimensional Elastic Phononic Crystals and Anharmonic Effects in Nano-Phononic Crystals ». Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/228156.

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This dissertation contains research directed at investigating the behavior and properties of a class of composite materials known as phononic crystals. Two categories of phononic crystals are explicitly investigated: (I) elastic phononic crystals and (II) nano-scale phononic crystals. For elastic phononic crystals, attention is directed at two-dimensional structures. Two specific structures are evaluated (1) a two-dimensional configuration consisting of a square array of cylindrical Polyvinylchloride inclusions in air and (2) a two-dimensional configuration consisting of a square array of steel cylindrical inclusions in epoxy. For the first configuration, a theoretical model is developed to ascertain the necessary band structure and equi-frequency contour features for the realization of phase control between propagating acoustic waves. In contrasting this phononic crystal with a reference system, it is shown that phononic crystals with equifrequency contours showing non-collinear wave and group velocity vectors are ideal systems for controlling the phase between propagating acoustic waves. For the second configuration, it is demonstrated that multiple functions can be realized of a solid/solid phononic crystal. The epoxy/steel phononic crystal is shown to behave as (1) an acoustic wave collimator, (2) a defect-less wave guide, (3) a directional source for elastic waves, (4) an acoustic beam splitter, (5) a phase-control device and (6) a k-space multiplexer. To transition between macro-scale systems (elastic phononic crystals) and nano-scale systems (nano-phononic crystals), a toy model of a one-dimensional chain of masses connected with non-linear, anharmonic springs is utilized. The implementation of this model introduces critical ideas unique to nano-scale systems, particularly the concept of phonon mode lifetime. The nano-scale phononic crystal of interest is a graphene sheet with periodically spaced holes in a triangular array. It is found through equilibrium molecular dynamics simulation techniques, that phonon-boundary collision effects and coherent phononic effects (band-folding) are two competing scattering mechanisms responsible for the reduction of acoustic and optical phonon lifetimes. Conclusions drawn about the lifetime of thermal phonons in phononic crystal patterned graphene are linked with the anharmonic, one-dimensional crystal model.

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Li, Xiang [Verfasser], Heinz [Akademischer Betreuer] Konietzky, Heinz [Gutachter] Konietzky, Wulf [Gutachter] Schubert et Guijun [Gutachter] Wang. « Lifetime prediction for rocks : a numerical concept based on linear elastic fracture mechanics, subcritical crack growth, and elasto-plastic stress redistributions / Xiang Li ; Gutachter : Heinz Konietzky, Wulf Schubert, Guijun Wang ; Betreuer : Heinz Konietzky ». Freiberg : Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://d-nb.info/1220698814/34.

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ACHILLI, SIMONA. « Spectral properties of adsorbates on metal surfaces via the embedding method ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2010. http://hdl.handle.net/10281/10827.

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Adsorbates on metal surfaces have attracted recently the scientific interest both from a fundamental point of view (quantum confinement) and in perspective of application in technology. In particular the electronic properties of such reduced symmetry systems are strictly related to their low dimensionality. An accurate theoretical description of their spectral properties has necessarily to deal with the absence of periodicity that characterizes these systems in one (thin films) or more (adatoms) directions. The embedding method allows to overcome this drawback considering a really infinite system both on vacuum and bulk side. In this thesis the ab initio spectral properties of single adatoms (alkali-metal atom and Ba) on Cu(111) and thin overlayers (K/Cu(111), Bi/Cu(100), O/Fe(100)) are analyzed, also in comparison with experimental results. The capabilities of the theoretical method adopted allow to evidence the role of the substrate band structure on the adsorbates induced electronic states. In particular the aspects related to the resonant charge transfer from the adsorbate's states to the bulk continuum are analyzed. This process represents an elastic decay channel for the surface electronic states and contributes to the elastic lifetime, that we can estimate according to the description of a continuous substrate band structure. The results presented for single adatoms evidence the blockade effect that a surface projected energy gap of the substrate produces on the resonant charge transfer. On the other hand the results relative to the overlayer allows to analyze the complex hybridization mechanism between surface features and substrate states in different points of the surface Brillouin zone. In addition the theoretical description of the electronic properties of overlayers on metal surfaces is devoted in this thesis also to the simulation of experimental findings, namely STM and STS images and photoemission spectra, showing the predictive character of the theoretical approach used.

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Poduška, 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.

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The lifetime of plastic pipes for water supply and other applications is demanded to exceed at least 50 years. Such a long lifetime is difficult to prove by standard testing methods like the hydrostatic pres-sure test. However, it is possible to calculate an estimation of the lifetime, as the most frequently oc-curring mechanism of failure of plastic pipes is the creep crack propagation and subsequent failure. The method is based on describing the crack propagation by parameters of the linear-elastic fracture mechanics. An important part of this method is a finite element simulation of crack propagation in a pipe loaded by various types of loads. Residual stress, a side product of solidification after extrusion, is one of these loads. This thesis begins with an introductory part and literature review of the relevant topics – most of all the typical material properties of the pipe materials, mechanisms of failure, methods of residual stress determination suitable for plastic pipes and their results, methods of testing the materials and calculating lifetime. After the introduction, the problems to be solved are defined. The description of the residual stress state in the wall of various plastic pipes is the main topic. Both tangential (hoop) and axial residual stress in pipes of different dimensions and materials are determined using a combination of experiments and numerical simulations. Also, a simplified method of tangential residual stress is designed that can provide a sufficiently precise description of the tangential resid-ual stress state and is not difficult to carry out. A method to include the residual stress in the lifetime calculations and its influence on the lifetime is also dealt with. Apart from residual stress, the influence of soil loads in case of a buried pipe is studied. The residual stress can also influence the experimental determination of crack growth rate. If the CRB (cracked round bar) test is used to measure the crack growth rate, the crack can propagate asymmetrically due to the presence of residual stress in the specimens, which affects the results. Based on a finite element simulation of crack propagation in a CRB specimen, the severity of the influence is assessed.

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Chapitres de livres sur le sujet "Elastic lifetime"

Rie, K. T., et R. M. Schmidt. « Lifetime Prediction Under Creep-Fatigue Conditions ». Dans Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials, 223–28. Dordrecht : Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3459-7_32.

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Kullig, E., H. Riesch-Oppermann, T. Winkler et A. Brückner-Foit. « Lifetime prediction for thermal fatigue : development of a stochastic model ». Dans Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials—3, 829–34. Dordrecht : Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2860-5_131.

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Aktaa, Jarir, et Bernd Schinke. « A Model for Damage and Lifetime Prediction Taking into Account the Backstress ». Dans Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials—3, 721–26. Dordrecht : Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2860-5_113.

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« Toughness ». Dans Damage Mechanisms and Life Assessment of High-Temperature Components, 21–57. ASM International, 1989. http://dx.doi.org/10.31399/asm.tb.dmlahtc.t60490021.

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Abstract The toughness of a material is its ability to absorb energy in the form of plastic deformation without fracturing. It is thus a measure of both strength and ductility. This chapter describes the fracture and toughness characteristics of metals and their effect on component lifetime and failure. It begins with a review of the ductile-to-brittle transition behavior of steel and the different ways to measure transition temperature. It then explains how to predict fracture loads using linear-elastic fracture mechanics and how toughness is affected by temperature and strain rate as well as grain size, inclusion content, and impurities. It also presents the theory and use of elastic-plastic fracture mechanics and discusses the causes, effects, and control of temper embrittlement in various types of steel.

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« Fatigue Life Relations ». Dans Fatigue and Durability of Structural Materials, 45–73. ASM International, 2006. http://dx.doi.org/10.31399/asm.tb.fdsm.t69870045.

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Abstract This chapter familiarizes readers with the methods used to quantify the effects of fatigue on component lifetime and failure. It discusses the development and use of S-N (stress amplitude vs. cycles to failure) curves, the emergence of strain-based approaches to fatigue analysis, and important refinements and modifications. It demonstrates the use of approximate equations, including the method of universal slopes and the four-point correlation technique, which provides reasonable estimates of elastic and plastic lines from information obtained in standard tensile tests. It also discusses high-cycle, low-cycle, and ultra-high cycle fatigue and presents several models that are useful for fatigue life predictions.

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Hug, J., et H. Zenner. « Influence of multi-axial loading on the lifetime in LCF strength ». Dans Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials, 217–22. Elsevier, 1998. http://dx.doi.org/10.1016/b978-008043326-4/50040-4.

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Kotte, K. L., et H. Zenner. « Lifetime prediction-comparison between calculation and experiment on a large data base ». Dans Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials, 721–28. Elsevier, 1998. http://dx.doi.org/10.1016/b978-008043326-4/50120-3.

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Actes de conférences sur le sujet "Elastic lifetime"

Szwedowicz, Jaroslaw, Piotr Bednarz, Christoph Meilgen et Jeff Samuelson. « Crack Growth Under Cyclic Loading and Plasticity Conditions ». Dans ASME Turbo Expo 2014 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25450.

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The increasing use of renewable energy sources to produce electricity requires additional operational flexibility from fossil-fuel gas and steam turbines. To compensate for renewable energy fluctuations in the electrical grid, a gas turbine (GT) engine needs to be more flexible, operating in peaking and partial loading modes as well as the base-load operation mode. Understanding how these different modes affect the lifetime of turbine components is critical to ensuring favourable RAM (Reliability, Availability, and Maintainability). Component lifetimes in peaking modes are limited by the number of thermo-mechanical cycles that a component can experience before crack initiation. The useful lifetime of some components can be increased by basing the predicted lifetime on the number of cycles for crack initiation plus the number of cycles for the crack to reach its maximum allowable length based on the fracture toughness K1C criterion for linear elastic fracture mechanics (LEFM). This is usually accomplished by using the Paris law to predict the rate of crack growth. Once cracks are formed, further propagation depends on the states of stress and strain near the cracks. These factors, which drive crack growth, can be quantified by the energy release rate. The Paris law predicts crack growth as a function of the energy release rate under linear elastic conditions, commonly for load controlled tests with load ration R>0. However, large thermal and mechanical loading can result in plastic deformation under cyclic loading conditions. Most GT components operate under strain controlled conditions generated by thermal loading. In this paper, a novel method is used to characterize crack growth under cyclic strain conditions in regions under plastic strain. The experimental data reveal that the rate of crack growth changes under plastic conditions in comparison with the linear elastic case. Especially compared to very high stress intensities ΔK of load controlled tests, here the allowable displacement limiting strain control matters. Applying experimental data from material tested under cyclic loading and elastic-plastic material response, component lifetime has been reliably predicted. Hereafter the developed method is referred to as elastic plastic fracture mechanics (EPFM) lifetime assessment. The EPFM approach more closely predicts the observed rate of crack growth than linear elastic fracture mechanics. LEFM over-predicts component lifetime for cracks growing in plastic regions under cyclic loading and could lead to catastrophic failure of a component. Therefore, the lifetime of a highly loaded component is more reliably assessed using the EPFM approach, as demonstrated for two alloys in this paper.

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Guediche, Amira, Hervé Piombini, Christophe Boscher, Bernard Perrin, Laurent Belliard, Nikolay Smagin, Mohammadi Ouaftouh et Marc Duquennoy. « Mechanical Characterizations of elastic layers made by sol-gel ». Dans Optical Interference Coatings. Washington, D.C. : Optica Publishing Group, 2022. http://dx.doi.org/10.1364/oic.2022.tea.6.

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To characterize the mechanical properties of elastic thin films to improve the lifetime of LMJ components, two experimental setups have been used: the acoustic picosecond techniques and the Surface Acoustic Wave InterDigital Transducers.

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Hu, Yifeng, Puning Jiang, Xingzhu Ye, Gang Chen, Junhui Zhang, Zhenzhen Hao et Lei Xiao. « Lifetime Assessment of Steam Turbine Casing ». Dans ASME Turbo Expo 2015 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43495.

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Nowadays, in order to accommodate electrical grids that include fluctuating supplies of green energy, more and more fossil power plants are increasingly required to start up and shut down frequently. The increased number of stress cycles leads to a significant reduction of lifetime. In this paper, numerous load cycles of steam turbine casing including various start up and shut down conditions were numerically investigated by using the finite element analysis (FEA). The total strain throughout the cycles was directly calculated by the elastic-plastic material model. The delta equivalent total strain was determined by rainflow count method, and the assessment of lifetime was evaluated.

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Trieglaff, Ralf, Christian Schrandt, Axel Schulz et Mayk Schulz. « TUEV NORD Concept Loop : Lifetime Optimisation of Pipelines ». Dans ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28755.

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LOOP is a concept to evaluate corroded or damaged pipelines based on detailed data from UT-pigging. The procedure of LOOP delivers a 3D-model generated from the data of a commercial in-line inspection tools (ultrasonic, magnetic flux). This makes it possible to use the full functionalities of the relevant finite element software like evaluation of wall-thinning (LOOP 1) and fracture mechanics analysis to evaluate cracks in the wall (LOOP 2). In this paper is given the basic ideas of the LOOP concept, where the main focus is directed to the LOOP 1 assessment procedure. Based on a real example of a corroded pipeline is demonstrated the assessment procedure, which is based on an elastic-plastic analysis of a real inner contour of the corroded surface transferred in the finite element geometry model. The unique element is that the surface data of the UT-pigging is used directly to generate the geometry model in the FE-software ANSYS. The assessment procedure is validated by a burst pressure test of a corroded pipeline. The result of the burst pressure test is compared with the calculated limit load from an elastic-plastic analysis based on measured material properties. Additionally, the assessment procedure is compared with the results of a limit load analysis based on DIN EN 13445-3 and with the results of the standard assessment procedure. At the end the assessment procedure is compared with the procedure given in API 579-1 standard.

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Allen, D. G., S. W. Kim et M. S. Sherwin. « Lifetime measurements of excited neutral donor states in GaAs detected by resonant elastic light scattering ». Dans 2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference. IEEE, 2006. http://dx.doi.org/10.1109/cleo.2006.4627700.

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Bunsell, Anthony R., Franc¸oise Barbier, Alain Thionnet, Hasnae Zejli et Brian Besanc¸on. « Damage Accumulation and Lifetime Prediction of Carbon Fiber Composite Pressure Vessels ». Dans ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-25978.

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Efficient storage of hydrogen is critical to the success of transition markets for hydrogen energy. For these near-term niche markets, high pressure compressed gas storage in carbon fiber composite pressure vessels is currently the most advanced and promising technology. However, challenges remain to improve performance and reliability while still insuring the safety of these pressure vessels in service over periods of 15 to 20 years. In order to avoid overdesign and conservative use, a fundamental understanding of damage mechanisms and degradation of these materials is required to fully exploit the potential of these materials. Acoustic emission has thus been used to characterize damage accumulation and its kinetics under static and cyclic loading in carbon fiber composite samples and pressure vessels. These experimental results were complemented by finite element modeling taking into account the elastic nature of the fibers, coupled with the visco-elastic behavior of the matrix and debonding at the fiber matrix interface.

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Martin, May L., Peter E. Bradley, Damian Lauria, Robert L. Amaro, Matthew Connolly et Andrew J. Slifka. « Strain-Life Performance in Hydrogen of a Dot Pressure Vessel Steel ». Dans ASME 2022 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/pvp2022-81492.

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Abstract Strain-life testing of a 4130 pressure vessel steel was conducted in air and in a high-pressure gaseous-hydrogen environment. Hydrogen causes an order of magnitude decrease in lifetime compared to in-air performance at the same strain-amplitudes. This decrease in lifetime in hydrogen is accompanied by various effects, such as a shift in the cyclic stress-strain curve, different influences on the elastic and plastic components of the strain-life data, and a distinct difference in the evolution of the microstructural texture prior to failure. For comparison, preliminary data from testing of a higher strength pressure vessel steel is presented, showing a difference in elastic/plastic partitioning may be accompanied by a difference in reduction in lifetime due to hydrogen.

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Bednarz, Piotr, et Jaroslaw Szwedowicz. « On Conservative CTOD Estimation Using Far Crack Deformation Field ». Dans ASME Turbo Expo 2013 : Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95411.

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In general engineering practice, crack tip opening displacement (CTOD) is very convenient approach for prediction of the components fracture mechanics (FM) lifetime. FM lifetime calculations are defined very well in industry and the lifetime prediction methods based on the CTOD resolve linear and nonlinear material behavior for monotonic and cyclic responses. The experiments confirm that under plasticity conditions the crack tip blunts for small scale or large scale yielding while, crack flanks open against each other only under elastic conditions. However, the CTOD application requires a very fine mesh in order to predict a crack tip deformation in reliable manner. Therefore, much more engineering work have to be involved in fine FE modeling. The crack tip flank deformation is crucial parameter responsible for reliable prediction of the nonlinear energy release rate, which is obtained from Hutchinson-Rice-Rosengren solution and the Shih rule. In accordance with design guidelines, the nonlinear energy release rate obtained from the CTOD must be evaluated conservatively to meet demands of RAM (Reliability, Availability and Maintainability). By using far crack deformation field, the paper proposes an engineering approach, which predicts the CTOD in a conservative manner under elastic-plastic conditions. This novel method is validated numerically by applying the well-known J-integral approach.

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Dong, Hui, Chang-Jiu Li, Hang Ding, Guan-Juan Yang et Cheng-Xin Li. « Effect of MCrAlY Bond Coat Temperature on Thermal Cyclic Lifetime of Plasma-Sprayed Thermal Barrier Coatings ». Dans ITSC2015, sous la direction de A. Agarwal, G. Bolelli, A. Concustell, Y. C. Lau, A. McDonald, F. L. Toma, E. Turunen et C. A. Widener. ASM International, 2015. http://dx.doi.org/10.31399/asm.cp.itsc2015p0795.

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Abstract Gradient thermal cycling test was performed on atmospheric plasma sprayed (APS) thermal barrier coatings (TBCs) to examine the influence of the bond coat temperature on the thermal cyclic lifetime. The TBC system consisted of Inconel 738 substrate, cold-sprayed NiCoCrAlTaY bond coat (BC) and plasma-sprayed yttria-stabilized zirconia (YSZ) top coat. Every thermal cycling test included 70s heating, 50s holding and 120s cooling. The temperature of top YSZ surface was about 1150 °C, while the bond coat temperatures were 900°C, 950°C and 1000°C, respectively. Results indicated that the lifetime of APS TBCs is significantly affected by bond coat temperature. A model to predict the relative thermal cyclic lifetime of TBCs at different bond coat temperature was established by taking account of main factors affecting the lifetime of TBCs. It was found that the predicted results are consistent with the observed results. As a result, the change of lifetime of APS TBCs mainly depends on the growth rate of thermally grown oxide (TGO), elastic modulus of YSZ and thermal expansion mismatch difference between YSZ and substrate caused by different bond coat temperature.

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Parker, Anthony P. « A Critical Examination of Sachs’ Material-Removal Method for Determination of Residual Stress ». Dans ASME 2003 Pressure Vessels and Piping Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/pvp2003-1832.

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Sachs’ method is an experimental procedure used primarily in the determination of residual stresses in autofrettaged thick cylinders. In its usual form it involves fixing axial and hoop direction strain gauges to the OD of a tube; strain readings are then obtained after each incremental removal of material from the bore. Sachs’ analysis assumes that the remaining tube unloads in linear-elastic fashion throughout the process and that superposition may therefore be employed to quantify the residual stresses within the original tube. By numerical simulation of two complete Sachs’ experimental sequences with ‘open end’ conditions it is demonstrated that the assumption of elastic unloading is invalidated by the Bauschinger effect. Sachs’ method thereby overestimates compressive residual bore hoop stresses in a typical tube by between 24% and 43%. If used as the basis for cyclic pressurization fatigue lifetime predictions with pre-existing cracks, such discrepancies will cause overestimates in fatigue lifetime of an order of magnitude. Sachs’ experimental procedure is therefore not recommended as a reliable or conservative method for determination of residual stress.

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