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Статті в журналах з теми "Thermo-mechanical cyclic loading"

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Ohno, Nobutada, Ryohei Yamamoto, and Dai Okumura. "Thermo-Mechanical Cyclic Plastic Behavior of 304 Stainless Steel at Large Temperature Ranges." Key Engineering Materials 725 (December 2016): 275–80. http://dx.doi.org/10.4028/www.scientific.net/kem.725.275.

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Thermo-mechanical cyclic experiments on 304 stainless steel were performed at several temperature ranges which had maximum temperatures ranging from 350°C to 1000°C and a minimum temperature of 150 °C. Related isothermal cyclic experiments were also performed. Temperature-history dependent cyclic hardening significantly occurred under thermo-mechanical cyclic loading with maximum temperatures around 600°C, whereas almost no cyclic hardening was observed when the maximum temperature was 1000°C. The observed thermo-mechanical cyclic plastic behavior in the saturated state of cyclic hardening was then simulated using a cyclic viscoplastic constitutive model, leading to the following findings. It was difficult to predict the saturated thermo-mechanical cyclic behavior using only the isothermal cyclic experimental data. The saturated thermo-mechanical cyclic behavior was simulated well by introducing a cyclic hardening parameter depending on the maximum temperature. This means that the cyclic hardening parameter should not change with temperature but depend on the maximum temperature in the saturated state of cyclic hardening under thermo-mechanical cyclic loading.
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Sehitoglu, Huseyin. "Material Behavior Under Thermal Loading." Journal of Pressure Vessel Technology 108, no. 1 (February 1, 1986): 113–19. http://dx.doi.org/10.1115/1.3264744.

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Material behavior under thermo-mechanical and isothermal loading cases is studied. The influence of constraint on thermo-mechanical deformation behavior is identified using a two-bar structure. Some of the possible microstructural mechanisms that may be operative under thermo-mechanical loading conditions are discussed. Isothermal tests are reported in the temperature range 20 to 600°C. Additional isothermal tests with step increases and decreases in temperature are performed to study the influence of temperature history on material behavior. During these tests, transient material behavior indicated temperature-strain history effects. Constitutive equations that capture essential features of material behavior under isothermal and thermo-mechanical loading cases are examined. Preliminary predictions of cyclic stress-strain loops are compared to experimental response. Further work is needed to incorporate temperature-strain history effects into constitutive equations.
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Hailemariam, Henok, and Frank Wuttke. "Cyclic mechanical stability of thermal energy storage media." E3S Web of Conferences 205 (2020): 07008. http://dx.doi.org/10.1051/e3sconf/202020507008.

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Closing the gap between supply and demand of energy is one of the biggest challenges of our era. In this aspect, thermal energy storage via borehole thermal energy storage (BTES) and sensible heat storage systems has recently emerged as a practical and encouraging alternative in satisfying the energy requirements of household and industrial applications. The majority of these heat energy storage systems are designed as part of the foundation or sub-structure of buildings with load bearing capabilities, hence their mechanical stability should be carefully studied prior to the design and operation phases of the heat storage system. In this study, the cyclic mechanical performance of a commercial cement-based porous heat storage material is analyzed under different amplitudes of cyclic loading and medium temperatures using a recently developed cyclic thermo-mechanical triaxial device. The results show a significant dependence of the cyclic mechanical behavior of the material, such as in the form of cyclic axial and accumulated plastic strains, on the different thermo-mechanical loading schemes.
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Koeberl, Hubert, Gerhard Winter, Martin Riedler, and Wilfried Eichlseder. "Failure Mechanism of Pure Nickel (Ni 200/201) under Thermo-Mechanical Loading." Key Engineering Materials 348-349 (September 2007): 793–96. http://dx.doi.org/10.4028/www.scientific.net/kem.348-349.793.

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Cyclic loading of metallic engineering components at constant elevated or fluctuating temperature causes a complex evolution of damage which be can hardly be described in a unique and straightforward manner. Often the thermal behaviour of the base metals is to weak, so thermal barrier coatings were needed. Nickel is generally used for such thermal barrier coatings. Therefore it is necessary to study the thermo-mechanical fatigue (TMF) of this material. The lifetime of these coatings is very strong affected by the temperature loading in general, both described by nodal temperatures and their local gradient. The thermal cyclic loading takes place as thermo-mechanical and low cycle fatigue (LCF) damage regime. To classify the thermo-mechanical failure mechanism of pure nickel, OP (out of phase) and IP-TMF (in phase) test series were examined. The use of damage parameters like the unified energy approach make sense, a more detailed life time calculation for pure Nickel can be done by using the Neu-Sehitoglu model. Summary, thermomechanical loadings activate multiple damage mechanism. Surface embrittlement by oxidation is the major distinctive mechanism in addition to pure fatigue damage. Different lifetime approaches were tested and analysed to fulfil the requirements for the fatigue analysis of nickel made components.
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Saad, Abdullah Aziz, Wei Sun, and Abdul Latif M. Tobi. "Multiaxial Viscoplasticity Modelling of Power Plant Steel." Key Engineering Materials 701 (July 2016): 230–34. http://dx.doi.org/10.4028/www.scientific.net/kem.701.230.

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The thermo-mechanical fatigue (TMF) of power plant components is caused by the cyclic operation of power plant. A time-dependent plasticity model can be used to simulate the component response under cyclic thermo-mechanical loading. This paper is concerned with the modelling of thermo-mechanical behaviour of power plant steel under various loading conditions. Fully-reversed, strain-controlled tests were conducted on a parent material of P91 steel at high temperatures in order to determine material constants. A unified, Chaboche viscoplasticity model, was used to model the TMF behaviour of the steel. The multiaxial form of the Chaboche constitutive equations have been implemented in the finite element software and validated by comparing to experimental data. Simulation results have been compared with the results of anisothermal cyclic testing in order to validate the performance of the model in cyclic temperature conditions. The model’s performance under multiaxial stress conditions was investigated by testing and simulating the notched bar specimen under load-controlled conditions.
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Prakash, R. V., T. Pravin, T. Kathirvel, and Krishnan Balasubramaniam. "Thermo-mechanical measurement of elasto-plastic transitions during cyclic loading." Theoretical and Applied Fracture Mechanics 56, no. 1 (August 2011): 1–6. http://dx.doi.org/10.1016/j.tafmec.2011.09.001.

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Hailemariam, Henok, and Frank Wuttke. "Cyclic Mechanical Behavior of Two Sandy Soils Used as Heat Storage Media." Energies 13, no. 15 (July 26, 2020): 3835. http://dx.doi.org/10.3390/en13153835.

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In this research, the cyclic mechanical behavior of two heat storage sandy soils is experimentally studied using a cyclic thermo-mechanical triaxial device. The results of the tests, which were performed under controlled temperature conditions between 20 and 60 °C, show a significant dependence of the mechanical response of the sandy soils with the amplitude of the cyclic loading and medium temperature. The mechanical performance and accumulation of plastic strains of the soils with an increasing number of loading cycles are discussed in view of the intrinsic soil behavior.
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Li, Dao-Hang, De-Guang Shang, Jin Cui, Luo-Jin Li, Ling-Wan Wang, Cheng-Cheng Zhang, and Bo Chen. "Fatigue–oxidation–creep damage model under axial-torsional thermo-mechanical loading." International Journal of Damage Mechanics 29, no. 5 (November 19, 2019): 810–30. http://dx.doi.org/10.1177/1056789519887217.

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A fatigue–oxidation–creep damage model that can take into account the effect of multiaxial cyclic feature on the damage mechanism is proposed under axial-torsional thermo-mechanical fatigue loading. In the proposed model, the effects of non-proportional additional hardening on fatigue, oxidation, and creep damages are considered, and the variation of oxidation damage under different high temperature loading conditions is also described. Moreover, the intergranular creep damage needs to be equivalent to the transgranular damage before accumulating with the fatigue and oxidation damages. The fatigue, oxidation, and creep damages can be expressed as the fractions of fatigue life, critical crack length, and creep rupture time, respectively, which allows the linear accumulation of different types of damages on the basis of life fraction rule. In addition, the proposed model is validated by various fatigue experimental results, including uniaxial thermo-mechanical fatigue, axial-torsional thermo-mechanical fatigue, and isothermal axial-torsional fatigue under proportional and non-proportional loadings. The results showed that the errors are within a factor of 2.
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Kumar, Ritesh, Akhilendra Singh, and Mayank Tiwari. "Investigation of crack repair using piezoelectric material under thermo-mechanical loading." Journal of Intelligent Material Systems and Structures 31, no. 19 (July 29, 2020): 2243–60. http://dx.doi.org/10.1177/1045389x20943946.

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This article presents an experimental investigation of repair of a crack in a structure using piezoelectric material under thermo-mechanical loading environment. The cyclic mechanical load is applied on a plate with a straight and angular crack under uniform temperature environment. Two cases have been considered for the repair of crack under (a) mechanical loading and (b) thermo-mechanical loading environment. A piezoelectric sensor is utilized to measure voltage. The measured voltage is used to calculate the stress intensity factor in passive and active modes. The effect of a single and double piezoelectric patch in the repair of the plate is investigated. The double piezoelectric patch is found to be more effective as compared to single patch when placed symmetrically offset from the crack. An optimal value of voltage and phase difference is evaluated for most effective crack repair. Location of the piezoelectric patch is varied with respect to crack location, and best-suited position for effective crack repair is proposed. The viability of piezoelectric used for repair under thermo-mechanical loading is discussed. The active mode of repair by piezoelectric is found to be effective under thermo-mechanical loading environment.
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COCKS, A. C. F., and F. A. LECKIE. "PERFORMANCE DIAGRAMS FOR CERAMIC MATRIX COMPOSITE COMPONENTS SUBJECTED TO CYCLIC THERMO-MECHANICAL LOADING." Journal of Multiscale Modelling 01, no. 03n04 (July 2009): 433–50. http://dx.doi.org/10.1142/s1756973709000165.

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Ceramic matrix composites (CMCs) are candidates for pressurized tubes which operate under conditions of severe cyclic thermal loading. Simple models describing the properties of CMCs are used to estimate the behaviour of a pressurized tube subjected to cyclic thermal loading and to establish shakedown and failure conditions. Analytical procedures are described which evaluate the component response in the cyclic state. The approach is illustrated by analysing the classical Bree problem assuming material properties which are representative of a SiC/SiC composite. Performance diagrams are presented which identify safe operating conditions and the extent of damage in the component.
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Дисертації з теми "Thermo-mechanical cyclic loading"

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Jannesari, Ladani Leila. "Damage initiation and evolution in voided and unvoided lead free solder joints under cyclic thermo-mechanical loading." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/4276.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.
Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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2

Belyaeva, A. I., A. A. Galuza, P. A. Khaimovich, I. V. Kolenov, Alla Aleksandrovna Savchenko, I. V. Ryzhkov, A. F. Shtan’, S. I. Solodovchenko та N. A. Shulgin. "Effect of the grain size on the precipitate distribution of the dispersion-strengthened СuСrZr alloy". Thesis, Національний науковий центр "Харківський фізико-технічний інститут", 2014. http://repository.kpi.kharkov.ua/handle/KhPI-Press/48167.

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Sutman, Melis. "Thermo-Mechanical Behavior of Energy Piles: Full-Scale Field Testing and Numerical Modeling." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/82438.

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Energy piles are deep foundation elements designed to utilize near-surface geothermal energy, while at the same time serve as foundations for buildings. The use of energy piles for geothermal heat exchange has been steadily increasing during the last decade, yet there are still pending questions on their thermo-mechanical behavior. The change in temperature along energy piles, resulting from their employment in heat exchange operations, causes axial displacements, thermally induced axial stresses and changes in mobilized shaft resistance which may have possible effects on their behavior. In order to investigate these effects, an extensive field test program, including conventional pile load tests and application of heating-cooling cycles was conducted on three energy piles during a period of six weeks. Temperature changes were applied to the test piles with and without maintained mechanical loads to investigate the effects of structural loads on energy piles. Moreover, the lengths of the test piles were determined to represent different end-restraining conditions at the toe. Various sensors were installed to monitor the strain and temperature changes along the test piles. Axial stress and shaft resistance profiles inferred from the field test data along with the driven conclusions are presented herein for all three test piles. It is inferred from the field test results that changes in temperature results in thermally induced compressive or tensile axial stresses along energy piles, the magnitude of which increases with higher restrictions such as structural load on top or higher toe resistance. Moreover, lower change in shaft resistance is observed with increasing restrictions along the energy piles. In addition to the design, deployment, and execution of the field test, a thermo-mechanical cyclic numerical model was developed as a part of this research. In this numerical model, load-transfer approach was coupled with the Masing's Rule in order to simulate the two-way cyclic axial displacement of energy piles during temperature changes. The numerical model was validated using the field test results for cyclic thermal load and thermo-mechanical load applications. It is concluded that the use of load-transfer approach coupled with the Masing's Rule is capable of simulating the cyclic thermo-mechanical behavior of energy piles.
Ph. D.
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Ab, Kadir Mariyana Aida. "Fire resistance of earthquake damaged reinforced concrete frames." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7969.

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The topic of structural damage caused by fires following an earthquake (FFE) has been discussed extensively by many researchers for over a decade in order to bring the two fields closer together in the context of performance based structural engineering. Edinburgh University, Heriot-Watt University, Indian Institute of Technology Roorkee (IIT Roorkee) and Indian Institute of Science initiated a collaboration to study this problem under a UK-India Engineering Research Initiative (UKIERI) funded project. The first construction of a single-storey reinforced concrete frame at IIT Roorkee was completed in summer 2011; this is known as the Roorkee Frame Test 1 throughout this thesis. This thesis presents the modelling of the Roorkee Frame Test 1 using the finite element method and assesses the capability of the numerical methodologies for analysing these two sequential events. Both two and three dimensional finite element models were developed. Beam and shell elements were chosen for the numerical modelling, which was carried out using the general purpose finite element package ABAQUS (version 6.8). The variation in material properties caused by these two types of loading, including strength and stiffness degradation, compressive hardening, tension stiffening, and thermal properties, is implemented in the numerical modelling. Constitutive material calculations are in accordance with EC4 Part 1.1, and all loading is according to IS 1893:2002 Part 1 (Indian Standard). The time-temperature curve used in the analysis is based on data from the test carried out. The behaviour of the Roorkee Frame Test 1 when subjected to monotonic, cyclic lateral loading followed by fire is presented. The capacity of the frame when subjected to lateral loading is examined using a static non-linear pushover method. Incremental lateral loading is applied in a displacement-controlled manner to induce simulated seismic damage in the frame. The capacity curve, hysteresis loops and residual displacements are presented, discussed and compared with the test results. The heat transfer analysis using three dimensional solid elements was also compared against temperature distributions recorded during the Roorkee frame fire test. Based on the smoke layer theory, two emissivity values were defined. In this study, the suitability of numerical modelling using ABAQUS to capture the behaviour of Roorkee frame test is examined. The results from this study show that the 3D ABAQUS model predicted more reliable hysteresis curves compared to the 2D ABAQUS model, but both models estimated the lateral load capacity well. However neither model was able to simulate the pinching effect clearly visible in the hysteresis curves from the test. This was due to noninclusion of the bond slip effect between reinforcing bars and concrete. The residual displacement obtained at the end of the cyclic lateral loading analysis from the 2D ABAQUS model is higher than that seen in the test. However, the result in the 3D ABAQUS model matched the trend obtained in the test. The both columns appear to stiffen under the heating and the residual displacement seems to recover slightly. Lateral displacements, obtained in the thermo-mechanical analysis of the numerical models, show that thermal expansion brings the frame back towards its initial position. Finally, correlation studies between analytical and experimental results are conducted with the objective to establish the validity of the proposed model and identify the significance of various effects on the local and global response of fire resistance earthquake damaged of reinforced concrete frames. These studies show that the effect of tension stiffening and bond-slip are very important and should always be included in finite element models of the response of reinforced concrete frame with the smeared crack model when subjected to lateral and thermal loading. The behaviour of reinforced concrete frames exposed to fire is usually described in terms of the concept of the fire resistance which defined in terms of displacement limit. This study shows the global displacement of the frame subjected to fire recover slightly due to the thermal expansion during the heating.
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Perkovic, Martin. "Mapping and characterisation of surface damage and wear mechanisms in gun barrels : Gun barrels exposed to cyclic thermo-mechanical loading." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-79026.

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Gun barrels are an important component in advanced defence systems. The gun barrels are used for direct and indirect fire and the material of the gun barrel is exposed to great strains and high temperatures. This sets high demands on the material of the gun barrel. During firing the gun barrel can be damaged. The first damage in gun barrels is the wear of the rifling followed by fatigue. When fatigue occurs cracks can propagate downwards into the bore and could result in catastrophic failure. Therefore investigation regarding the wear, the mechanisms and the underlying factors causing the damage will be performed. How and where the wear in gun barrels occur and also which wear mechanisms causing the wear. Wear in gun barrels involves extreme conditions during firing such as high gas pressure and high temperature from the burning propellant. This thesis work aims to understand how and why wear and damaging mechanisms in gun barrels occurs. Moreover how other ballistic factors influences have on the wear. The wear in gun barrels is caused by erosion from the combustion gases or/and sliding wear caused by the high-speed projectile. The phenomena of wear are complicated and factors like deformation state, types of wear, environment and process are interrelated with each other. These give the rise of wear. In this thesis, samples from three gun barrels were analysed. A new unworn gun barrel, a medium worn gun barrel and a severely worn gun barrel. From the used gun barrels 4 critical positions were identified, then samples from both surface and cross-section were obtained from the gun barrels. The surface and cross-section were analysed using different methods including optical light microscopy and scanning electron microscopy to characterise the surface damage and wear mechanisms. The results from the investigation revealed the dominating wear mechanism to be thermal and chemical erosion at the positions closest to the combustion chamber with heat checks as its signature feature. The heat checks are associated with fatigue cracks developed at the surface and during thermo-mechanical loading, allows it to propagate down into the surface. For both samples at position 2, after the start of the rifling, adhesive wear was obtained too. The adhesive wear was induced by material pick-up from the driving band of the projectile during sliding. In other meaning, the material is transferred from the counter-face to the bore surface. The severely worn gun barrel had been subjected to sliding wear at the muzzle end compared to the medium worn gun barrel which hadn’t experience the same wear rate at the same position. The analysis of the cross-section examination revealed information about the structure and condition of the material. To obtain more information about mechanical properties, a hardness test was performed. The hardness test revealed a hard but brittle surface which can be sheared by the frictional force caused by the sliding projectile. The analysis of the gun barrels revealed information about wear mechanisms and damages in medium and severely worn gun barrels. The detected wear mechanism was thermal erosion, chemical erosion, mechanical erosion and sliding wear.
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Maghsoodi, Soheib. "Thermo-mechanical behavior of soil-structure interface under monotonic and cyclic loads in the context of energy geostructures." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0031.

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L'incorporation d'échangeurs de chaleur dans des géostructures conventionnelles comme les pieux peut extraire la chaleur du sol à des fins de chauffage et l'injecter dans le sol à des fins de refroidissement. Ces dernières années, des recherches ont été menées à l'échelle réelle et en laboratoire pour étudier l'effet de la température sur le comportement géotechnique de ces géostructures énergétiques ainsi que sur le sol environnant. En effet, ces géostructures énergétiques peuvent être soumises à des charges mécaniques cycliques et a des variations thermiques tout au long de leur durée de vie. L'objectif de cette étude était d'approfondir la compréhension du comportement du contact sable/argile-structure sous des charges thermomécaniques complexes. Un dispositif de cisaillement direct à température contrôlée permettant d'effectuer des essais monotones et cycliques à charge normale constante ou à rigidité normale constante a été mis au point. La réponse de l'interface aux effets thermiques sur le comportement mécanique des sols et l'interface sol-structure a été étudiée. Le sable de Fontainebleau et l'argile kaolin ont été utilisés comme substituts pour les sols sableux et argileux. Les résultats ont montré que les variations thermiques appliquées ont un effet négligeable sur la résistance au cisaillement de l'interface entre le sable et la structure du sol. Dans les échantillons d'argile, l'augmentation de la température a augmenté la cohésion et par conséquent la résistance au cisaillement, en raison de la contraction thermique pendant le chauffage. L'adhérence de l'interface argile-structure était inférieure à la cohésion des échantillons d'argile. Pour étudier les effets de la charge mécanique cyclique sur l'interface argile-structure à différentes températures, des essais de cisaillement direct monotone et cyclique à volume équivalent non drainé ont été réalisés sur l'interface argile-argile et argile-structure à différentes températures. Les résultats ont montré que le nombre de cycles jusqu'à la rupture pour l'essai d'interface argile-structure était inférieur à celui du cas argile-argile dans la même gamme de rapports de contraintes de cisaillement cycliques et moyennes. L'augmentation de la température a réduit le taux d'accumulation des contraintes et le nombre de cycles jusqu'à la rupture a été multiplié par 2 ou 3. Le taux de dégradation (paramètre de dégradation, t) a diminué de 16% avec un chauffage de 22 à 60 °C pour les différents rapports de contrainte cyclique testés. Un modèle d'interface sol-structure non isotherme basé sur la théorie de l'état critique a ensuite été développé. Le modèle non isotherme prend en compte l'effet de la température sur le taux de vide de l'interface avant le cisaillement. Le modèle est capable de saisir l'effet de la température sur l'interface sol-structure dans des conditions de charge normale constante et de rigidité normale constante pour les interfaces sableuses et argileuses. Les paramètres supplémentaires ont des significations physiques et peuvent être déterminés à partir d'essais classiques en laboratoire. La formulation est en bon accord avec les résultats expérimentaux et les principales tendances sont correctement reproduites
Incorporation of heat exchangers in conventional geostructures like piles can extract the heat from the soil for heating purposes and inject it to the soil for cooling purposes. In recent years, research has been conducted at full and laboratory scale to investigate the effect of temperature on the geotechnical behavior of these energy geostructures as well as on the surrounding soil. Indeed, these energy geostructures can be subjected to cyclic mechanical loads and thermal variations throughout their lifetime. The aim of this study was to deepen the understanding regarding the behavior of sand/clay-structure contact under complex thermo-mechanical loads. A temperature-controlled direct shear device to perform monotonic and cyclic constant normal load or constant normal stiffness tests was developed. The response of the interface to the thermal effects on the mechanical behaviour of soils and soil-structure interface was investigated. Fontainebleau sand and kaolin clay were used as proxies for sandy and clayey soils. The results showed that the applied thermal variations have a negligible effect on the shear strength of the sand and sand-structure interface. In clay samples the temperature increase, increased the cohesion and consequently the shear strength, due to thermal contraction during heating. The adhesion of the clay-structure interface, was less than the cohesion of the clay samples. To investigate the mechanical cyclic load effects on the clay-structure interface at different temperatures, monotonic and cyclic constant-volume equivalent-undrained direct shear tests were performed on clay-clay and clay-structure interface at different temperatures. The results showed that, the number of cycles to failure for the clay-structure interface test was lower than that for the clay-clay case in the same range of cyclic and average shear stress ratios. Increasing the temperature, decreased the rate of strain accumulation and the number of cycles to failure increased by 2-3 times. The rate of degradation (degradation parameter, t) decreased by 16% with heating from 22 to 60oC for the different cyclic stress ratios tested. A non-isothermal soil-structure interface model based on critical state theory was then developed. The non-isothermal model takes into account the effect of temperature on the void ratio of interface prior to shearing. The model is capable to capture the effect of temperature on soil-structure interface under constant normal load and constant normal stiffness conditions for both sandy and clayey interfaces. The additional parameters have physical meanings and can be determined from classical laboratory tests. The formulation is in good agreement with the experimental results and the main trends are properly reproduced
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Devaux, Ophélie. "Analysis and optimization of mixed-mode conical adhesively bonded joints under thermo-mechanical loadings." Thesis, Brest, 2015. http://www.theses.fr/2015BRES0048/document.

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Анотація:
Dans I'industrie spatiale, I'optimisation des structures composites du point de vue cycles de fabrication, gain de masse et amélioration des performances passe aujourd'hui par I'introduction de jonctions collées en remplacement/complément de liaisons boulonnées ou rivetées. Les lanceurs sont des structures complexes qui nécessitent de prendre en compte les contraintes liées à la fabrication de structures de grandes tailles, I'influence des conditions de transport et de stockage, ainsi que les différents spectres de chargements thermo-mécaniques rencontrés au cours de la phase de lancement. Le but de ce travail a été de développer un outil prédictif du comportement mécanique de I'adhésif Hysol EA-9321, matériau utilisé dans cette étude, à tout instant du cycle de vie de la structure sur lequel il est utilisé, la structure SYLDA. La caractérisation et la modélisation d'un couplage thermo-cinétique d'un tel adhésif ont tout d'abord été réalisées en vue de déterminer la distribution du taux de polymérisation et de la température dans un assemblage collé quel que soit le chargement thermique appliqué. Le comportement mécanique de l'adhésif a ensuite été étudié expérimentalement via I'essai Arcan Evolution, ce qui a constitué une base de données expérimentales à divers taux de polymérisation adaptée à I'identification du modèle de comportement. Plusieurs modèles élasto-plastique et élasto-visco-plastique basés sur celui de Mahnken-Schlimmer ont été implantés dans un code de calcul éléments finis afin de prédire le comportement 3D de l'adhésif Hysol EA-9321. Une procédure globale d'identification, basée sur un couplage entre calculs éléments finis et une procédure d'optimisation, a permis d'identifier les différents paramètres des lois de comportement. Une extension de ces modèles à la visco-élasticité a été numériquement proposée. Enfin, une comparaison numérique entre une liaison conique et une liaison semblable à celle trouvée sur la structure spatiale étudiée a permis de proposer un essai représentatif du comportement de I'adhésif sur un tel assemblage. Cet essai servira, dans une étude complémentaire, à valider les modèles de comportement développés
In the aerospace industry, composite structures are nowadays optimized with adhesively bonded joints supplemented by/or completed with mechanical fasteners such as bolts, rivets or welds. The structural design of launch vehicles is complex and must take into account lot of constraints related to large-scale structures, influence by environment conditions during storage, transport stages and thermo-mechanical stresses applied during launcher's flight. The purpose of this work was to provide a numerical tool for predicting the mechanical behaviour of the Adhesive Hysol EA-9321 in a spatial bonded assembly such as the SYLDA structure during its life course. First of all, a thermo-kinetic coupling was experimentally and numerically investigated to describe the couple (curing degree-temperature) in a bonded assembly regardless of the thermal load applied. Then, an experimental database was made by studying the mechanical behaviour of the adhesive under proportional loadings, using the Arcan Evolution experimental device. Cure-dependent elastoplastic and elasto-visco-plastic model based on Mahnken-Schlimmer constitutive laws were proposed in order to describe the 3D mechanical behaviour of the adhesive Hysol EA-9321. A global identification strategy allowed identifying material parameters by coupling finite element computations and optimization procedure. An extension of those models to the visco-elasticity was evenly provided. At last, a conical bonded joint and a bonded assembly in the SYLDA structure were numerically compared to propose a test representative of the adhesive behaviour in the SYLDA. The latter will aim at validating the constitutive laws established
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8

Guruprasad, Y. K. "Repair and Retrofit Strategies for Structural Concrete against Thermo-Mechanical Loadings." Thesis, 2014. http://hdl.handle.net/2005/3040.

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Reinforced cement concrete (RCC) structures have become an important aspect in most of the buildings in our society around the world. Most of the multistoried reinforced concrete buildings house important institutions such as hospitals, schools, government establishments, defense establishments, business centers, sports stadiums, super markets and nuclear power plants. The cost of construction of such multistoried RCC structures is very high, and these structures need to be maintained and restored based on their functionality and importance using repair and retrofit strategies when these structures undergo damage. The steps involved in restoring RCC structures that have damages using repair / retrofit measures consists of identifying the source or cause of damage, assessment of the degree or extent of damage that has taken place using nondestructive techniques. Based on the assessment of degree of damage suitable repair / retrofit strategy using the appropriate repair material is applied to achieve the required load carrying capacity or strength. The present work involves assessing the efficacy of carbon fibre reinforced polymer (CFRP) based system applied on pre-damaged structural members to restore the member’s strength and stiffness through experimental investigations and finite element predictions. To validate the macrolevel properties of predamaged concrete micromechanical analysis, microscale studies and analytical investigations have been conducted. Plain and reinforced concrete test specimens: cylinders, square prisms and rectangular prisms having 25MPa and 35MPa cylinder compressive strengths pre-damaged due to mechanical (monotonic and cyclic loading) and thermal loading (exposure to different temperature and time durations) with applications of CFRP repair subjected to compression is investigated to study the behavior and enhancement in the compressive strength and stiffness after application of repair. Non destructive testing of thermally damaged concrete (exposed to different temperature and exposure time) is conducted using ultrasonic pulse velocity and tomography methods to understand the degradation in the strength and stiffness of thermally damaged concrete. The results of the non destructive testing helps in assessing the amount of repair that can be applied. To validate the macro scale behavior of thermally damaged concrete micro scale studies was performed adopting micro indentation, petrography, Raman spectroscopy, scanning electron miscroscopy (SEM) and Electron probe micro analysis (EPMA). During the event of a fire in RC structures which have been retrofitted. The high temperature caused due to fire tends to make the concrete to deteriorate and the repair material to delaminate. Loss of strength/ stiffness in concrete and delamination of the repair material in a retrofitted structural component in a structure causes instability which results in partial collapse or complete collapse of the structure. Thermal insulation of concrete and the repair material (CFRP) using geo-polymer mortar and simwool thermal fibre blanket exposed to high temperature and different exposure time are experimentally investigated. This is to evaluate the effectiveness of the thermal insulation in protecting epoxy based structural repair material(CFRP) from thermal damage and to minimize the delamination of the repair material when exposed to high temperatures. Slender columns when loaded eccentrically fail at a load much lesser than their actual load carrying capacity. In RC buildings where additional floors need to be added, in those situations slender columns which are already eccentrically loaded tend to get damaged or fail due to additional load which act on them. Therefore to restore such columns experimental and finite element investigations on reinforced concrete slender columns having 25MPa cylinder compressive strength subjected to eccentric monotonic compressive loading with applications of CFRP repair is studied to understand the behavior and the enhancement in load carrying capacity after application of repair. Experimental investigations are conducted to study fracture and fatigue properties of thermally damaged concrete geometrically similar notched plain and reinforced concrete beams having 25MPa cylinder compressive strength exposed to different combinations of temperature and durations with application of repair (CFRP). Nonlinear fracture parameters of thermally damaged concrete is computed which help in understanding the fracture behavior of thermally damaged concrete and application of repair. Effectiveness of CFRP repair and failure behaviour of these beams are studied when these thermally damaged notch concrete beams are subjected to monotonic and cyclic (fatigue) loading. Reinforced concrete slender beams when subjected to unexpected loads such as earthquakes get damaged. The increase in load carrying capacity and fatigue life of reinforced concrete slender beams having 25MPa cylinder compressive strength in flexure subjected to monotonic and cyclic loading with applications of CFRP repair is investigated using experimental and finite element investigations. Finite element analysis of concrete specimens pre-damaged due to mechanical (monotonic and cyclic loading) / thermal loading (exposure to different temperature and time durations) with applications of CFRP repair and assessment of amount of repair required is investigated. Analytical (empirical) models are developed to assess the mechanical properties of concrete (elastic moduli, compressive strength and split tensile strength) exposed to different temperatures and time durations. Nonlinear fracture parameters of geometrically similar plain concrete notch beams exposed to different temperature and time durations are determined. Fracture parameters (stress intensity factor) of thermally damaged plain and reinforced concrete notched beams with application of CFRP have been determined. Effect of size and shape of thermally damaged plain concrete compression members with application of CFRP wrap have been studied. Crack mouth opening displacements (CMOD), strains and crack lengths of thermally damaged plain concrete (PC) notched beams using digital image correlation has also been determined.
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9

Chang, Hsiu-Tao, and 張秀桃. "Temperature Cycling Loading/ Thermo-Mechanical Behaviors on Lead-Free Solder Joints of Wafer Level Chip Scale Packages." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/52675464171556697810.

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碩士
中原大學
機械工程研究所
93
The miniaturized and unleaded packages in IC manufacturing made a tremendous impact. Each material of solder joints used to IC packages has various supporters, but it cannot be incorporated and integrated identically at present. The finite element simulation with 2D model is hard to simplify in reliability analysis. First, this study investigates different models with 2D and 3D. In accordance with the result, it adopts one-eighth model to analyze with the finite element software and Taguchi method. The orthogonal array of is utilized to probed the effects and behaviors of strain under five temperature loading parameters of temperature ramp rate, high and low dwell temperature, and dwell temperature time. Furthermore, the study investigates thermal mechanical behavior of the four solder joint materials under four temperature loading. The result shows that 2D model differs from 3D model in one order. This study selects one-eighth model in all kinds of 3D model to estimate the reliability. In the serious study, the temperature range is the main factor to the magnitude of the strain range from the Taguchi experiment. Second, it can be found that the temperature range is the most significant factor on elastic-plastic-creep analysis under four temperature loadings, and the temperature ramp rate affects slightly. This result is the same as the Taguchi experiment. The purpose in serious study is to provide more information of the thermal mechanical behavior of lead-free solder toward the standard parameter of thermal cycling test in the future.
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Частини книг з теми "Thermo-mechanical cyclic loading"

1

Bouchou, A., and P. Delobelle. "Thermo-Mechanical Behaviour and Modelling of an Austenitic Stainless Steel under Anisothermal Cyclic Loadings." In Fatigue under Thermal and Mechanical Loading: Mechanisms, Mechanics and Modelling, 435–44. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-015-8636-8_45.

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2

Sparr, Holger, Daniela Schob, and Matthias Ziegenhorn. "Thermo-Mechanical Material Modelling for Cyclic Loading a Generalized Modelling Approach to Different Material Classes." In Lecture Notes in Mechanical Engineering, 705–11. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-04975-1_81.

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3

Sehitoglu, Huseyin, and D. Slavik. "Critical Experiments in Thermo-Mechanical Loading." In Low Cycle Fatigue and Elasto-Plastic Behaviour of Materials, 177–83. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3459-7_26.

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4

Audigier, V., S. Lasserre, and J. L. Lataillade. "Thermo-Mechanical Behaviour of Surface Mount Solder Joint During Thermal Cycling." In Fatigue under Thermal and Mechanical Loading: Mechanisms, Mechanics and Modelling, 475–85. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-015-8636-8_49.

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5

Chen, W., A. Dudka, H. Chen, D. Mukherji, R. P. Wahi, and H. Wever. "Damage and Fatigue Life of Superalloy IN738LC under Thermo-Mechanical and Low Cycle Fatigue Loading." In Fatigue under Thermal and Mechanical Loading: Mechanisms, Mechanics and Modelling, 97–102. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-015-8636-8_10.

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6

Komenda, J., L. Lindé, and P. J. Henderson. "Microstructural Aspects of Damage Occurring during Thermo-Mechanical and Low Cycle Fatigue Testing of an Oxide Dispersion Strengthened Alloy." In Fatigue under Thermal and Mechanical Loading: Mechanisms, Mechanics and Modelling, 339–47. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-015-8636-8_36.

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Тези доповідей конференцій з теми "Thermo-mechanical cyclic loading"

1

Schaaf, A., M. De Monte, C. Hoffmann, M. Vormwald, and M. Quaresimin. "Damage mechanisms in PBT-GF30 under thermo-mechanical cyclic loading." In PROCEEDINGS OF PPS-29: The 29th International Conference of the Polymer Processing Society - Conference Papers. American Institute of Physics, 2014. http://dx.doi.org/10.1063/1.4873852.

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2

Lagoudas, Dimitris C., Pavlin B. Entchev, and Parikshith K. Kumar. "Thermomechanical Characterization of SMA Actuators Under Cyclic Loading." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-42933.

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Shape memory alloy (SMA) wire actuators have been increasingly used in various devices and applications due to their high energy density and simple design. With the use of these actuators the questions of size effects on their behavior need to be addressed. This paper presents a study on the cyclic loading behavior of large diameter SMA wires subjected to different thermo-mechanical loading paths. Wires of two different diameters are investigated in the current study—1.78 mm and 2.16 mm. The issues addressed in this work include the investigation and design of a gripping technique for the large diameter wires to avoid slippage and study of heat treatment conditions for optimized superelastic behavior. After the heat treatment, specimens are subjected to cyclic mechanical loading. Two different cyclic loading patterns have been investigated: loading up to a given value of stress or up to a given value of strain.
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3

Gehlot, Sarendra, Pradeep Mahadevan, and Ragupathy Kannusamy. "Analytical Correction of Nonlinear Thermal Stresses Under Thermo-Mechanical Cyclic Loadings." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-69287.

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Automotive turbocharger components frequently experience complex Thermo-Mechanical Fatigue (TMF) loadings which require estimation of nonlinear plastic stresses for fatigue life calculations. These field duty cycles often contain rapid fluctuations in temperatures and consequently transient effects become important. Although current FE software are capable of performing these nonlinear finite element analyses, the turnaround time to compute nonlinear stresses for complex field duty cycles is still quite significant and detailed design optimizations for different duty cycles become very cumbersome. In recent years, a large number of studies have been made to develop analytical methods for estimating nonlinear stress from linear stresses. However, a majority of these consider isothermal cases which cannot be directly applied for thermo-mechanical loading. In this paper a detailed study is conducted with two different existing analytical approaches (Neuber’s rule and Hoffman-Seeger) to estimate the multi-axial nonlinear stresses from linear elastic stresses. For the Neuber’s approach, the multi-axial version proposed by Chu was used to correct elastic stresses from linear FE analyses. In the second approach, Hoffman and Seeger’s method is used to estimate the multiaxial stress state from plastic equivalent stress estimated using Neuber’s method for uniaxial stress. The novelty in the present work is the estimation of nonlinear stress for bilinear kinematic hardening material model under varying temperature conditions. The material properties including the modulus of elasticity, tangent modulus and the yield stress are assumed to vary with temperature. The application of two analytical approaches were examined for proportional and non-proportional TMF loadings and suggestions have been proposed to incorporate temperature dependent material behavior while correcting the plasticity effect into linear stress. This approach can be effectively used for complex geometries to calculate nonlinear stresses without carrying out a detailed nonlinear finite element analysis.
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4

Springer, Martin, Michael Nelhiebel, and Heinz E. Pettermann. "Fatigue crack growth modeling in the metallization of power semiconductors under cyclic thermo-mechanical loading." In 2016 17th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE). IEEE, 2016. http://dx.doi.org/10.1109/eurosime.2016.7463373.

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5

Basaran, Cemal, and Hong Tang. "Implementation of a Thermodynamic Framework for Damage Mechanics of Solder Interconnects in Microelectronic Packaging." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-32874.

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A thermo mechanical fatigue life prediction model based on the theory of damage mechanics is presented. The damage evolution, corresponding to the material degradation under cyclic thermo mechanical loading, is quantified thermodynamic framework. The damage, as an internal state variable, is coupled with unified viscoplastic constitutive model to characterize the response of solder alloys. The damage-coupled viscoplastic model with kinematic and isotropic hardening is implemented in ABAQUS finite element package to simulate the cyclic softening behavior of solder joints. Several computational simulations of uniaxial monotonic tensile and cyclic shear tests are conducted to validate the model with experimental results. The behavior of an actual Ball Grid Array (BGA) package under thermal fatigue loading is also simulated and compared with experimental results.
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6

Kim, Kyubum, K. Anne Juggernauth, and Samantha H. Daly. "Stress-Induced Martensitic Phase Transformation in Nitinol Under Hard Cyclic Loading." In ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3609.

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This paper describes an experimental study of stress-induced martensitic phase transformation in the shape memory alloy Nickel-Titanium, also known by the trade name Nitinol. The rich local thermo-mechanical interactions that underlie phase transformation are examined using three-dimensional Digital Image Correlation (to determine local strain fields) and infrared imaging (to determine local thermal fields). We quantify the complex local interactions between released/absorbed latent heat and the extent of transformation, and explore the characteristics of the phase fronts. There exists a remarkable amount of memory in the pattern of the martensitic formation from cycle to cycle. The initial pattern in which the martensite nucleates and propagates in the first cycle strongly dictates how the martensite nucleates and propagates in future cycles. The presence of this cycle-to-cycle strain pattern memory indicates that the local elastic stress fields in the martensite are driven by a dislocation structure and martensitic nuclei that largely stabilize during the first loading cycle.
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Szwedowicz, Jaroslaw, Piotr Bednarz, Christoph Meilgen, and Jeff Samuelson. "Crack Growth Under Cyclic Loading and Plasticity Conditions." In 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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Sharma, Pradeep, and Abhijit Dasgupta. "The Connection Between Microstructural Damage Modeling and Continuum Damage Modeling for Eutectic Sn-Pb Solder Alloys." In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-39185.

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Researchers resort to a wide range of simplified representations at the continuum scale, to model creep-fatigue damage in viscoplastic heterogeneous materials such as Sn-Pb eutectic solders, caused by thermo-mechanical and mechanical cyclic loading (e.g. due to power cycling, environmental temperature cycling, vibration, etc). Typically, in macroscale phenomenological damage models, the cyclic damage is assumed to depend on some loading parameter such as cyclic strain range, work dissipation per cycle, partitioned strain range, partitioned work dissipation per cycle, cyclic entropy changes, cyclic stress range, integrated matrix creep, etc. In many instances, some of these variables are weighted with a factor to account for rate-dependent effects. The task of finding the best damage metric is difficult because of complex microstructural interactions between cyclic creep and cyclic plasticity due to the high homologous temperature under operating conditions. In this study we use insights obtained from microstructural and more mechanistic modeling to identify the most appropriate macro-scale damage metrics. The microstructural models are based on such phenomena as grain boundary sliding, blocking of grain boundary sliding by second-phase particles, grain boundary, volumetric and surface diffusion, void nucleation, void growth and plastic collapse of cavitating grain boundaries. As has been demonstrated in the literature, microstructural models suggest that fatigue damage caused by cyclic plasticity should correlate well with the two most commonly used damage indicators: both cyclic strain range and plastic work dissipation per cycle. This study, however, demonstrates that in the case of damage dominated by cyclic creep, microstructural models developed by the authors indicate closer correlation with creep work dissipation per cycle, than with cyclic creep strain range.
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Ishikawa, Nobuyuki, Mitsuo Kimura, Hitoshi Asahi, Mitsuru Sawamura, Tomohiko Omura, and Hirofumi Kishikawa. "Near Neutral pH SCC of Grade X80 Linepipe Steels Under Cyclic Loading." In 2008 7th International Pipeline Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ipc2008-64281.

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Susceptibility to stress corrosion cracking (SCC) of Grade X80 linepipe steels, which were produced by recent TMCP (Thermo-Mechanical Controlled Processing) technique, controlled rolling (CR) followed by accelerated cooling process (ACC), in near neutral pH conditions was investigated, and cracking behavior was compared with conventional Grade X65 linepipe. Longitudinal strip specimens with small surface notches were cyclically loaded in the NS4 solution with cathodic polarization of −1000mV vs. SCE. No significant difference in susceptibility to SCC was found between Grades X80 and X65 linepipes, both produced by TMCP process, even under higher stress condition for X80 linepipe steel. Hydrogen permeation test reviled the strong effect of hydrogen for the cracking under the SCC test condition. Transgranular cracking and quasi-cleavage fracture were observed as an evidence of the effect of both corrosion and hydrogen embrittlement on near neutral pH SCC.
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10

Hormozi, Mohammad R., Farid Biglari, and Kamran M. Nikbin. "Investigation of Stress Stabilization Behavior of Type 316 Steel." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97593.

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Some materials are designed to operate at high temperature environments with high thermal gradients and will be subject to thermal and mechanical cyclic strains. Under these cyclic temperatures and strains, thermo-mechanical fatigue (TMF) and low cycle fatigue (LCF) failure occur which will lead to the initiation of damage and cracking and subsequent crack growth. In this paper the numerical and experimental investigations of stress stabilization of 316FR steel subjected to strain cycling in the temperature range of 400–650 °C has been presented. The material exhibited both cyclic and nonlinear kinematic hardening behavior. In this paper the finite element analysis of cyclic loading of the materials was based on a direct method to use the test data from a stabilized cycle in combination with the hysteresis strain energy concept for damage derivation.
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