Дисертації з теми "Variable amplitude loading (VAL)"
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Hooper, J. "Fretting fatigue under variable amplitude loading." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/11046.
Повний текст джерелаHooper, Jeremy. "Fretting fatigue under variable amplitude loading." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/11046.
Повний текст джерелаBAKHTIARI, SAEEDEH. "Fatigue behaviour of welded components under variable amplitude loading." Thesis, KTH, Maskinkonstruktion (Inst.), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-141773.
Повний текст джерелаDetta examensarbete, som utförts för Volvo CE, behandlar utmattningsprov av svetsade konstruktioner. Teknikutveckling och förändrade kundkrav på högre kvalitet till en lägre kostnad är drivkrafter för Volvo CE att investera i produkt- och metodutvecklingsprojekt, som exempelvis det aktuella projektet att optimera vikt och tillverkningskostnad för boggi-balkar till dumprar. Detta projekt är en fortsättning av ett tidigare arbete som hade som mål att verifiera utmattningslivslängden för en boggibalk till en dumper predikterad med FEM, genom att utmattningsprova balken för oscillerande last. Som en del av projektet modifieras en existerande provningsrigg. Töjningar på balken mats med ett antal töjningsgivare monterade på balken. Spännings och töjningfrån den simulerade modellen analyseras och utmattningslivslängden jämförs för olika metoder för att prediktera utmattning. Slutligen jämförs och veriferas dessa metoder.
Xiang, Zhang. "Numerical simulation of fatigue crack propagation under variable amplitude loading." Thesis, Imperial College London, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308604.
Повний текст джерелаAguilar-Espinosa, Aaron Alejandro. "Effect of variable amplitude loading on fatigue crack growth rate." Thesis, Oxford Brookes University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496022.
Повний текст джерелаRodopoulos, C. A. "Fatigue studies under constant and variable amplitude loading in MMCs." Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245575.
Повний текст джерелаRazmjoo, Gholam Reza. "A fracture mechanics approach to fatigue crack propagation under variable amplitude loading." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259194.
Повний текст джерелаMassingham, M. "Fretting fatigue under variable amplitude loading and the role of contact geometry." Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/11430.
Повний текст джерелаMassingham, Matthew. "Fretting fatigue under variable amplitude loading and the role of contact geometry." Thesis, Cranfield University, 2005. http://dspace.lib.cranfield.ac.uk/handle/1826/11430.
Повний текст джерелаShamsaei, Nima. "Multiaxial Fatigue and Deformation Including Non-proportional Hardening and Variable Amplitude Loading Effects." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1279760342.
Повний текст джерелаShenoy, Vikram. "Damage characterisation and lifetime prediction of bonded joints under variable amplitude fatigue loading." Thesis, Loughborough University, 2009. https://dspace.lboro.ac.uk/2134/5400.
Повний текст джерелаGates, Nicholas R. "Fatigue Behavior under Multiaxial Stress States Including Notch Effects and Variable Amplitude Loading." University of Toledo / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1469637495.
Повний текст джерелаZitounis, Vasilios. "Fatigue crack growth rates under variable amplitude load spectra containing tensile underloads." Thesis, Cranfield University, 2003. http://dspace.lib.cranfield.ac.uk/handle/1826/105.
Повний текст джерелаDin, Khafilah Binti. "Fatigue crack propagation under variable amplitude loading analysed by fracture mechanics and finite element analysis." Thesis, University of Manchester, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334012.
Повний текст джерелаPost, Nathan L. "Reliability based design methodology incorporating residual strength prediction of structural fiber reinforced polymer composites under stochastic variable amplitude fatigue loading." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/26492.
Повний текст джерелаPh. D.
Pierron, Quentin. "Caractérisation de la fatigue des assemblages soudés soumis à des chargements à amplitude variable." Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2018. https://pastel.hal.science/tel-03920237.
Повний текст джерелаIn the automotive field, engineers are designing lighter and more reliable parts to meet new emissions standards. Arc-welded parts of the chassis must be resistant to fatigue despite relatively thin steel sheet. To assess welded joints fatigue, constant amplitude loadings are used: for fatigue characterization of materials and assemblies but also for mechanical field calculations. However, in-service loadings are very different. Bumps on the road, cornering and braking induce complicated time evolutions of the loading. Several models translate the complex evolution of efforts into an equivalent constant amplitude loading. Among these models, linear cumulative damage model consider that the damage created by a loading cycle is independent on the previous loading. However, this fact is contradicted by most of the literature results. This hypothesis can lead to significant design errors. Alternative damage accumulation models from the literature are evaluated. Moreover, thin welded structures are tested to determine how the damage accumulates under variable amplitude loading. Care has been taken to design, instrument, model and understand these tests. The effects of residual deformation due to welding and specimens clamping are analyzed and considering. To follow indirectly the damage evolution, dissipation is identified from temperature field measurement. It is an extension of the method of characterization of the fatigue limit by self-heating to finite life domain for welded structures under variable amplitude loading. These tests reveal two opposing effects of nonlinear damage accumulation. On the one hand, overloads create residual compression stresses that increase the life of welded joints. On the other hand, the repetition of overloads prevents the occurrence of local elastic shakedown. Considering these tests, recommendations are finally given for the choice of relevant fatigue tests loadings and damage accumulation models suitable for welded structures
Post, Nathan L. "Modeling the Residual Strength Distribution of Structural GFRP Composite Materials Subjected to Constant and Variable Amplitude Tension-Tension Fatigue Loading." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/36196.
Повний текст джерелаMaster of Science
Kyriacou, S. A. "Experimental and theoretical studies into the fatigue crack propagation behaviour of the 7075 aluminium-zinc alloy under constant and variable amplitude loading." Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280937.
Повний текст джерелаArcari, Attilio. "Enhanced strain-based fatigue methodology for high strength aluminum alloys." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/26178.
Повний текст джерелаPh. D.
Miyaura, Edson Haruo. "Modélisation de fatigue et de mécanique de la rupture d'une structure éolienne soumise au chargement dynamique et aléatoire du vent." Thesis, Rouen, INSA, 2016. http://www.theses.fr/2016ISAM0005/document.
Повний текст джерелаThe objective of this thesis is to demonstrate how to do theoretical analyses of fatigue and fracture mechanics in a structure for horizontal axis wind turbine. The chain of calculations required to reach this objective is particularly long for two reasons : firstly, the wind speed varies randomly with time , secondly, the vibration amplitude of the mast is amplified due to its natural frequencies of vibration. A whole chapter is dedicated to modeling the wind speed in space and time. The same chapter shows how to synthesize a random signal by employing a power spectral density function (PSD). The axial force of the rotor is the most important loading on a structure for horizontal axis wind turbine. This force has a non linear relation with the wind speed. This implies the need to determine the PSD of the axial force from its signal, by employing a spectral estimation method. The Thomson Multitaper method revealed to be the most satisfactory for this application. The PSD of displacement of the mast is determined by associating the receptance of the structural system and the PSD of the force representing all loadings. Finally, a signal of stress can be synthesized from its PSD. The fatigue cycle counting method known as rainflow is discussed and employed. The fact that the signal of stress has a variable amplitude implies the need of a more sophisticated method to simulate a crack propagation. The method chosen in this thesis is called strip-yield
Solomon, Daniel Maurice. "Effects of Mission Overloads on Fatigue Crack Growth in Ti-6Al-2Sn-4Zr-2Mo." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1532083676103601.
Повний текст джерелаSharifimehr, Shahriar. "Multiaxial Fatigue Analysis under Complex Non-proportional Loading Conditions." University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1544787705876488.
Повний текст джерелаDimithe, Aboumou Loïc. "Etude expérimentale et simulation numérique de propagation de fissures dans un acier inoxydable martensitique durci par précipitation sous conditions représentatives en termes de température, spectre de chargement et vieillissement." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2017. http://www.theses.fr/2017ESMA0013/document.
Повний текст джерелаConnecting the turbofan engine to the wing of the aircraft, the engine pylon is a true « masterpiece » of the aircraft. Indeed, it transmits all the aircraft engine efforts. It is subject to temperature variations from -40°C in cruise to 290°C-400°C during take off and landing. In addition, the engine pylon is a prey to very high vibratory stresses, which should be properly taken into account during damage tolerances analysis to avoid the loss of the aircraft. Between 290°C and 400°C, the martensite of components in precipitation-hardenable stainless steel (15-5 PH) of engine pylon undergoes microstructural transformation (« ageing »). This ageing has a significant impact on the mechanical properties, characterized by an increase in yield strength and tensile stress and drastic reduction in toughness and ductility. To complete the characterization of the effects of ageing on the mechanical properties while considering that these structures are designed according to a principle of damage tolerance, the aim of this work is to study the fatigue crack growth behavior (FCGB) of this material according to the ageing conditions and the test temperature. The approach is based on knowledge of monotonous and cyclic behavior to analyze the fatigue crack mechanisms. The cyclic behavior tests have been carried out at room temperature and 300°C at different strains imposed levels, on the 15-5PH steel in its as-received and then to the ageing conditions realized, between 300°C and 400°C and exposure times of up to 10 000h. The results highlight the lack of influence of ageing on the cyclic hardening of 15-5 PH steel, both at room temperature to 300°C. For the range of ΔK values tested, the FCGB of the 15-5PH steel under constant load amplitude is not affected by ageing. However, the extent of the stable propagation domain is itself reduced according to the degree of aging at room temperature. This reduction is due to the fall of fracture toughness due to ageing. The fracture surfaces are mainly transgranular for all conditions examined. However, the areas close to the final rupture ofsome ageing statements present islands indicative of a static failure mode at room temperature. These islands are absent to 300°C.Under the effect of repeated loads, a delayed effect on the crack velocity has been demonstrated. This delay is a function of the overload rate, overload period, the number of overloads and the baseline load ratio, but insensitive to ageing. Furthermore, are duction in the extent of the area stable propagation is also noticed at room temperature. Fatigue crack growth simulations undervariable amplitude loading were made through the incremental model for damage tolerance analysis developed by LMT-Cachan. The model results were then subject to a comparison with the PREFFAS model used at AIRBUS. The incremental model is well aware ofsome of the effects of repeated overloads. It also proves less conservative than the model PREFFAS. For taking account the effects of ageing in the incremental model, simply report the hardening observed on old material, the cyclic hardening parameters are notaffected. A methodology based on time/temperature equivalence provided by Hollomon-Jaffe - and taking into account the effects of ageing in the incremental model is finally proposed
Colin, Julie Anne. "Deformation History and Load Sequence Effects on Cumulative Fatigue Damage and Life Predictions." University of Toledo / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1260390033.
Повний текст джерелаNešpůrek, Lukáš. "STOCHASTIC CRACK PROPAGATION MODELLING USING THE EXTENDED FINITE ELEMENT METHOD." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-233900.
Повний текст джерелаDallmeier, Johannes. "Experimental analysis and numerical fatigue modeling for magnesium sheet metals." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-209124.
Повний текст джерелаRuchert, Cassius Olivio Figueiredo Terra. "Estudo da inferência de carregamento em histórias de vôos simulados na liga de Al aeronáutico SAE-AMS 7475 T7351." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-22092008-131854/.
Повний текст джерелаThe loading inference and the fractographic reconstruction of fatigue crack propagation rate in simulated flight stories, as Twist, mini-Twist, Falstaff and mini-Falstaff were investigated in this work. The studied material was an aluminum alloy SAE-AMS 7475 T7351. Tensile and hardness tests were carried out in order to determine mechanical properties, as well as chemical and microstructure analysis of the material. C(T) specimens were extracted from a block of material for constant amplitude load testing and M(T) specimens were extracted from a plate and were tested in variable amplitude loading. The curves (da/dN vs. ΔK) for constant-amplitude loading were obtained from fatigue crack propagation tests performed in L-T and T-L directions in C(T) specimens for R (0.1; 0.3; 0.5; 0.7 and 0.8), at room temperature, according to ASTM-E647 (1993). Two different constant loading fatigue tests were performed. At constant ΔP and distinct values of R for obtaining data of stages II and III of da/dN - ΔK curves; and at constant ΔK and increasing the R ratio to be used in the inference of constant amplitude loading in the relation of H/s striation morphology (obtained from fractographic images) and the loading ratio, R. Additionally, fracture toughness tests were executed in T-L and L-T directions, according to ASTM-E1820 (1999). The macroscopic and microscopic fatigue crack propagations were compared and good correlation was obtained for the range 0.1-1.0 μm/cycle, for all R values. By using the K factor parametrization method, Berkovitz (1995), the loading spectrum was estimated for the distinct R-values and the results were compared to the actual spectrum imposed by the test machine. Variable amplitude tests were performed in M(T) specimens by applying simulating flight spectra normalized by NLR, as Twist, mini-Twist, Falstaff and mini-Falstaff, in a servohydraulic test machine MTS, in which a Flextest GT controller was coupled. The suppression of less severe loading flights showed a great influence in fatigue crack propagation life, in simulated flight tests Twist and mini-Twist, but not in Falstaff and mini-Falstaff. The acceleration and slowing down of fatigue crack were observed in the d2a/dflight - a curve obtained from variable loading tests. The fractured surfaces of some samples were examined by the fractographic technique of blocking marks recognition. A good reconstitution of fatigue crack propagation rate of a simulated flight like Falstaff was obtained by the measurements of marks in the fracture surfaces of the more severe flights, in MEV images.
(12868682), Gary D. Kreiser. "Fatigue life of metals with particular reference to nonlinear damage accumulation under variable amplitude loading." Thesis, 2004. https://figshare.com/articles/thesis/Fatigue_life_of_metals_with_particular_reference_to_nonlinear_damage_accumulation_under_variable_amplitude_loading/20063894.
Повний текст джерелаFatigue in engineering components and structures subjected to cyclic loading is characterised by the process of accumulation of damage over a period of time. This phenomenon of damage accumulation could potentially lead to catastrophic failures. Unfortunately the occurrence of such failures is difficult to predict due to a limited understanding of the fatigue process particularly under variable amplitude loading (VAL). Fatigue life of metals is usually determined from linear damage rule (LDR) that offers sufficient level of conservatism and accuracy, particularly for high cycle fatigue (HCF) loading blocks typified by magnitudes of stresses well within elastic limit and period exceeding millions of cycles. However, for low cycle fatigue (LCF) associated with a relatively small number of high amplitude load cycles causing bulk plastic strain, the damage process is affected by the amplitude and sequence of plastic strain. Past attempts to apply the LDR to predict fatigue life for LCF have been largely unsuccessful. Irrespective of the various modifications proposed, the LDR has failed to capture the nonlinear accumulation of damage observed for certain load sequences within VAL spectra, where at least a portion of the loads cause plastic strain. Amongst the variety of LCF life prediction models proposed in the literature, those based on the energy approach of continuum damage mechanics (CDM) provide significant scope to further the development as they conform to the principles of thermodynamics and hysteretic energy dissipation. This thesis presents an energy based nonlinear damage accumulation (NLDA) model that utilises the CDM concept and a cumulative damage parameter to account for nonlinear damage accumulation under VAL. The fatigue life predictions of the NLDA model for metals subjected to constant, high amplitude, strain controlled loading, compare well with the experimental data reported in the literature. The nonlinear capability of the NLDA model has been demonstrated using a well established two-step block -loading test.
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 джерелаIbrahim, Elfaitori. "Fatigue Life Assessment of 30CrNiMo8HH Steel Under Variable Amplitude Loading." Thesis, 2012. http://hdl.handle.net/10012/7216.
Повний текст джерела"Sub cycle Corrosion fatigue Crack Growth under Variable Amplitude Loading." Master's thesis, 2019. http://hdl.handle.net/2286/R.I.54990.
Повний текст джерелаDissertation/Thesis
Masters Thesis Aerospace Engineering 2019
Mikheevskiy, Semen. "Elastic-Plastic Fatigue Crack Growth Analysis under Variable Amplitude Loading Spectra." Thesis, 2009. http://hdl.handle.net/10012/4402.
Повний текст джерела"Subcycle Fatigue Crack Growth Formulation for Constant and Variable Amplitude Loading." Master's thesis, 2016. http://hdl.handle.net/2286/R.I.40326.
Повний текст джерелаDissertation/Thesis
Masters Thesis Mechanical Engineering 2016
Yang, Chia Han, and 楊佳翰. "Reliability and Fatigue Life Assessment of Rotational Shafts under Variable Amplitude Loading." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/38739919439561100261.
Повний текст джерела國立臺灣大學
機械工程學研究所
88
High-cycle fatigue is one of the major reasons that cause cracks at the shaft of the reactor coolant pump (RCP) of the domestic Maanshan nuclear power plant. In order to study the fatigue problem of the shaft, experimental work is carried out using a rotatory bending test machine in the present study. The experiment includes constant-amplitude, two-stress-level, three-stress-level and random-amplitude fatigue tests. Considerably large amounts of tests are performed for some particular cases with a view to studying the so-called ‘fatigue reliability’ of the tested material. After all tests are completed, analytical work is performed. The analytical work includes the construction of the P-S-N curve (Probabilistic S-N curve), the investigation of the probability distribution of the fatigue life, the examination of applicability of different damage accumulation rules, and the develop of simple formulas for the prediction of fatigue damage and fatigue life when random loading is concerned. After careful study, several conclusions are drawn in the present thesis for the tested material. First, the fatigue life follows a Weibull or normal probability distribution. Secondly, the Corten-Dolan, Marco-Starkey along with some fatigue damage accumulation rules provide better damage prediction than the others do. Thirdly, the proposed fatigue damage prediction algorithm can be extended from two-stress-level, three-stress-level to multi-stress-level as well as the case of random loading, although more experimental study is needed for the last case. It is believed that the about results are helpful for engineers working in the nuclear power plant to assess the integrity and safety of the RCP.
Mehrzadi, Morteza. "FATIGUE CHARACTERIZATION OF AM60B MAGNESIUM ALLOY SUBJECTED TO CONSTANT AND VARIABLE AMPLITUDE LOADING WITH POSITIVE AND NEGATIVE STRESS RATIOS." 2013. http://hdl.handle.net/10222/21837.
Повний текст джерелаEl-Zeghayar, Maria. "The Introduction of Crack Opening Stress Modeling into Strain-Life and Small Crack Growth Fatigue Analysis." Thesis, 2011. http://hdl.handle.net/10012/5716.
Повний текст джерелаAraújo, Francisco João Duarte de. "Influence and stability of deep rolling residual stresses in the steel AISI 1045 subjected to multi-level loads." Master's thesis, 2013. http://hdl.handle.net/10316/38811.
Повний текст джерелаO objectivo deste trabalho é estudar a influência e estabilidade de tensões residuais no comportamento à fadiga no aço AISI 1045. O processo de laminagem profunda foi usado como tratamento mecânico para introduzir no material um estado de tensões residuais compressivas em zonas próximas da superfície. Testes à fadiga uniaxiais foram realizados de modo a avaliar o comportamento à fadiga do material tratado mecanicamente. Foram definidas três amplitudes de 300, 350 e 400 MPa aplicadas em ciclos de tensão constante e combinadas em ciclos de tensão variável. As tensões residuais e a largura do pico de difracção foram calculadas através de difracção de raio-X. O polimento electrolítico foi usado como processo para remover camadas de material. Medições de dureza foram realizadas de forma a fazer uma ligação entre o endurecimento causado pela laminagem profunda e o comportamento à fadiga. Os resultados mostram que o comportamento do material sujeito à fadiga é influenciado pela tensão aplicada. Elevadas amplitudes de tensão provocam elevadas deformações plásticas e menor resistência à fadiga. É observada uma melhoria do comportamento à fadiga do material tratado mecanicamente em relação ao não tratado. O material sujeito à fadiga exibe uma relaxação de tensões residuais que é mais pronunciada para amplitudes de tensão mais altas. Em fadiga de tensão variável, a deformação plástica aumenta ou diminui quando se varia a tensão aplicada. O número de ciclos aplicados em cada bloco de tensão influencia a estabilidade das tensões residuais induzidas. A relaxação das tensões residuais é bastante influenciada para ciclos de tensão constante seguidos de apenas meio ciclo com uma tensão mais alta ou mais baixa do que a tensão anterior.
The main objective of the work presented is the study of the influence and stability of near surface zone of deep rolled steel AISI 1045 subjected to cyclic loading. Deep rolling process was applied as a mechanical surface treatment to induce a compressive residual stress state in near surface zones of material. Tension/Compression fatigue tests were performed in order to evaluate cyclic deformation behaviour after the mechanical surface treatment. Three stress amplitudes of 300, 350 and 400 MPa were used in constant amplitude loading and combined in variable amplitude loading. Residual stress and FWHM (full width at half maximum) distribution measurement were carried out by X-ray diffraction regarding the influence of cyclic loading on near surface zone properties stability. Electropolishing was utilized as a removal material process. Microhardness measurements were carried out concerning determination of work hardened surface layers. Results show that cyclic deformation behaviour is influenced by stress amplitude. High stress amplitudes lead to high strain amplitudes and low fatigue lifetimes. An improvement of lifetime is achieved for deep rolled specimen showing the influence of mechanical surface treatment on fatigue lifetime. Residual stress distribution exhibits a relaxation due to cyclic loading, which is higher for higher stress amplitudes. In variable amplitude loading, a change of stress amplitude leads to an increase or decrease of plastic strain amplitude for higher or lower stress amplitudes, respectively. The number of cycles of each load block influences stability of residual stress state. A load block in constant amplitude loading followed by only half of one cycle of higher or lower stress amplitude than the previous block influences significantly residual stress relaxation.