Дисертації з теми "Fatigue multiaxiale du caoutchouc"
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Dong, Shanyan. "Etude de la fatigue du caoutchouc naturel sous sollicitation multiaxiale." Paris, CNAM, 2009. http://www.theses.fr/2009CNAM0678.
Повний текст джерелаRubber is widely used in the industry. One of the major problems encountered in the applications of rubber remains still the prediction of the fatigue life of rubber. Since the components industrial undergo complex loading, we focus our subjects on fatigue of rubber under complex loading in this study. The objectives of this study should include the following points:1) To have a good understanding of the mechanism of multiaxial fatigue of rubber;2) To identify the existing approaches for analyzing the multiaxial fatigue of rubber, and hen develop a new approach;rubber, 3) To evaluate the existing and new approaches according to the test results. In order to accomplish these objectives, three different specimens are adopted. With these specimens we carry out several series of fatigue test under axial and biaxial loading on an INDTRON biaxial fatigue machine. The simulation of the specimens is performed by Finite Element Method. The fatigue lives of rubber are studied according to the test results. The tomography method is used to study the damage inside the rubber during the fatigue process by a medical scanner. Finally, the fatigue crack surfaces are examined by S. E. M
Beurrot-Borgarino, Stéphanie. "Cristallisation sous contrainte du caoutchouc naturel en fatigue et sous sollicitation multiaxiale." Phd thesis, Ecole centrale de nantes - ECN, 2012. http://tel.archives-ouvertes.fr/tel-00835499.
Повний текст джерелаBeurrot, Stéphanie. "Cristallisation sous contrainte du caoutchouc naturel en fatigue et sous sollicitation multiaxiale." Ecole Centrale de Nantes, 2012. https://tel.archives-ouvertes.fr/tel-00835499.
Повний текст джерелаNatural rubber is well-known for its excellent mechanical properties in multiaxial fatigue and those are generaly attributed to the ability of the material to crystallize when strained. However, the relationship between strain-induced crystallization and mechanical properties of natural rubber has never been established. The aim of this thesis is therefore to understand the origin of the great multiaxial fatigue properties of carbon black-filled natural rubber, by considering two small scales of study, as opposed to the macroscopic scale generally considered. The first part of this thesis is dedicated to uniaxial crack growth and energy dissipation mechanisms at the cracks and micro-cracks scale ; those mechanisms are determined thanks to original in-situ propagation tests observed with scanning electron microscope. In the second part of the thesis, strain-induced crystallization is studied at the macromolecular scale, in static multaxial deformation on the one hand and in uniaxial fatigue on the other hand, thanks to X-ray diffraction measurements performed at the Soleil synchrotron facility. The characteristics of crystallites, i. E. Their size, orientation, number and lattice parameters, are measured during the different mechanical tests. We observe that in multiaxial deformation, the crystallites are similar in size and have the samei lattice parameters than those nucleated in uniaxial deformation, but their orientation strongly varies with the multiaxiality of the deformation and is not influenced by the loading path. Finally, we show that in uniaxial fatigue, the characteristics of the crystallites evolve with the number of cycles, differently depending on the minimum and maximium stretch ratios reached at each cycle
Layouni, Khaled. "Comportement et fatigue multiaxiale d'un élastomère chargé (NR-CB)." Paris, ENMP, 2004. http://www.theses.fr/2004ENMP1242.
Повний текст джерелаThis work explores the mechanical behaviour of a carbon-black reinforced natural rubber (NR-CB) subjected to monotonic, cyclic, uniaxial and multiaxial loading. Several physical phenomena have been identified. In particular, we have characterised the material compressibility under various kinds of loading conditions and confirmed the results by means of microscopic observations. Consequently, in order to describe the material behaviour, we have considered and compared two constitutive models: the first one is hyperelastic incompressible whereas the second one is more realistic as it uses a damage-induced compressible approach. Furthermore, fatigue experimental results obtained under complex loading histories allow to describe the interaction between axial and torsional loading. In particular, the phase angle effect on the lifetime and the crack location have been determined. These analyses were supported by fractographic observations that allow the identification of different tearing steps (macroscopic scale) and initiation sites (microscopic scale). Finally, we have established a model able to predict the location and orientation of cracks, as well as lifetime under complex loading. This criterion has been validated for complex geometry and industrial components. Finally, we have compared this model with another taken in literature
Warneboldt, Iona. "Multiaxial fatigue design of elastomeric parts using Equivalent Fatigue Loads." Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2022. http://www.theses.fr/2022ENTA0002.
Повний текст джерелаThis thesis introduces an Equivalent Fatigue Load (EFL) approach for the multiaxial fatigue design of elastomeric parts. As direct Finite Element Analysis (FEA) calculations of automotive in-service loads (Road Load Data (RLD)) are too expensive, the objective is to derive simplified load blocks as a realistic input for numerical damage calculations. Three streps are applied for this method: the localization method, the material damage function and the EFL determination process. Various fatigue tests have been conducted (415 samples) to study the fatigue behavior of this complex type of relaxing and non-relaxing multiaxial loading on natural rubber specimens. Lifetime and crack features are analyzed to eventually introduce an appropriate critical planebased fatigue measure and to establish a novel mean strain effect model. This criterion is generalized throughout an original critical plane search method. To estimate the local mechanical response (localization method), this thesis identifies an axes-coupling method that is fitted for the nonlinear nature of elastomeric structures. It is based on the multiplicative decomposition of the deformation gradient tensors. These two steps are then implemented in the framework of the EFLdetermination process. For this, a global optimization method is added to determine the simplified load blocks, causing locally the same fatigue behavior in the given structure. The computational costs of this optimization are reduced by only considering a subset of the most damaged material points for EFLdetermination. Finally, the method has been challenged on a specimen to outline its capabilities and to validate the approach
Raoult, Ida. "Structures élastomères sous chargement cyclique : comportement, fatigue, durée de vie." Phd thesis, Ecole Polytechnique X, 2005. http://tel.archives-ouvertes.fr/tel-00521633.
Повний текст джерелаPoisson, Jean-Louis. "Détermination d'un critère de fatigue multiaxial appliqué à un élastomère synthétique." Phd thesis, Université François Rabelais - Tours, 2012. http://tel.archives-ouvertes.fr/tel-00780307.
Повний текст джерелаMorel, Franck. "Fatigue multiaxiale sous chargement d'amplitude variable." Poitiers, 1996. http://www.theses.fr/1996POIT2364.
Повний текст джерелаSermage, Jean Philippe. "Fatigue thermique multiaxiale à température variable /." Cachan : Laboratoire de mécanique et technologie, 1998. http://catalogue.bnf.fr/ark:/12148/cb370383779.
Повний текст джерелаWeber, Bastien. "Fatigue multiaxiale des structures industrielles sous chargement quelconque." Lyon, INSA, 1999. http://theses.insa-lyon.fr/publication/1999ISAL0056/these.pdf.
Повний текст джерелаThe work of thesis deals with multiaxial fatigue. Its purpose is the fatigue life assessment of industrial structures submitted to any kind of solicitations, from the most basic case, which is uniaxial and periodical, to the most general one, which is multiaxial and of variable amplitude. The first part is dedicated to the study of multiaxial fatigue stress-based criteria. 37 criteria issued from the literature are analysed. They are divided into empirical, critical plane and global approaches. 24 criteria are validated through 233 multiaxial fatigue tests issued also from the literature. The second part aims at taking into account the stress gradient effect within the multiaxial criteria formulation. Similarly to some recent work, the stress gradient effect is introduced within the Laboratory's criteria. These propositions are validated through combined bending-torsion tests. A proposition is made to calculate the stress gradient field from finite elements results obtained over any complex industrial structure. The third part describes the evolution of the Laboratory's fatigue life prediction method under multiaxial random loading. The first step presents a plane per plane damage accumulation. The fatigue damage is calculated and cumulated on physical planes. The second step shows the influence of the so-called counting variable on the fatigue life prediction results, and leads to a new concept: the cycle counting and the damage assessment are performed plane per plane. This procedure avoids the dependence of the choice of the counting on the life assessments. A critical plane approach criterion is required for these latter methods. This work is integrated to an industrial software called Sollife allows one to simulate the fatigue behaviour of any complex structure. The first results are in good assessment with experiments. They show the important effect of metal forming process (as stamping) and result in lots of perspectives
Sauzay, Maxime. "Effets de surface et d'anisotropie en fatigue multiaxiale." Cachan : Laboratoire de mécanique et technologie, 2000. http://catalogue.bnf.fr/ark:/12148/cb37217577j.
Повний текст джерелаWeber, Bastien Boivin Maurice. "Fatigue multiaxiale des structures industrielles sous chargement quelconque." Villeurbanne : Doc'INSA, 2004. http://docinsa.insa-lyon.fr/these/pont.php?id=weber.
Повний текст джерелаDhahri, Hager. "Endommagement en fatigue multiaxiale avec effet d’environnement REP." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLY002/document.
Повний текст джерелаThe lifetime extension of the nuclear power plants is considered as a major energy challenge. For this reason, the risk analysis and the study of various effects of different factors that could potentially represent a hazard to a safe long term operation are necessary. These structures, often of large dimensions, are subjected during their life to complex loading combining varying mechanical and multiaxial loads, with non-zero mean values associated with temperature fluctuations and Pressurized Water Reactor (PWR) environment.In this context, the present study is part of the identification of the PWR environment effect and the equibiaxiality of the loading on the fatigue life of the austenitic stainless steels present in the primary pipes of a Pressure Water Reactor.For this purpose, the CEA has developed, in partnership with EDF and FRAMATOME, the experimental device «FABIME2e» for studying the equibiaxial fatigue in the PWR environment.First, a presentation of the experimental and numerical results obtained with the FABIME2e device is realized. These results show the aggravating effect of equibiaxial loading and environmental PWR conditions on the fatigue life of austenitic stainless steel. This effect remains covered by the Design curve defined by the design codes of the nuclear industry. Second, a new fatigue criterion is proposed to predict the lifetime in equibiaxial fatigue. This criterion takes into account the effect of the PWR environment.This work opens up several industrial and scientific prospects on the mechanical inter-pretation of equibiaxial fatigue tests in PWR environment and on the proposed fatigue criterion
Froustey, Catherine. "Fatigue multiaxiale en endurance de l'acier 30 NCD 16." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37605220r.
Повний текст джерелаAbecassis, Manon. "Fissuration de matériaux soudés en condition de fatigue multiaxiale." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEM021/document.
Повний текст джерелаThis study is devoted to i) the experimental characterization of fatigue crack path and fatigue crack growth rate (FCGR) for welded materials under mixed mode of loading ii) the analysis of fatigue crack to microstructure interactions for two types of welded materials and iii) the identification of a relevant FCGR criterion function of the mode mixity.The experimental characterization was achieved for a ferritic stainless steel, welded by metal inert gas, using CCT specimens for different orientations of the notch. Biaxial testing was achieved using central crack cross-shaped specimen, varying the shear to opening loading ratio, for a dissimilar welded joint obtained by laser welding of Ti17 and Ti6242 Ti base alloys.For the ferritic stainless steel, the crack is both trans- and intergranular for the base metal, whereas it becomes mainly transgranular for the welded specimen. Nevertheless, very slight modification of the FCGR, comparing base metal and welded material, is observed. The welding was seen to be detrimental only in the case of macroscopic shear loading implied by the geometry of the notch. For Ti17, crack path is very smooth and FCGR evolves regularly as a function of the stress intensity factor (SIF). Instead of what, for Ti6242 alloy, both the crack path and the FCGR present large amplitudes of oscillation, due to a strong interaction with alpha needles. The FCGR is lower in Ti6242 than in Ti17 for equibiaxial fatigue, whereas the FCGR is higher in Ti6242 than in Ti17 for macroscopic shear fatigue loading. For welded Ti17-Ti6242 specimens, FCGR is higher than observed in base metal for crack within the fusion zone (FZ), and tends to the FCGR of the associated base metal to each heat-affected zone (HAZ-Ti17 and HAZ-Ti6242).The case of Ti17 was seen to be relevant to determine an equivalent SIF function of mode mixity within the scope of LEFM. An original criterion has been established taking into consideration mode I, II and III. The numerical model describes explicitly both surface crack path and flat to slant orientation of the crack. This criterion has been successfully applied to both Ti and Fe base alloys, for base metal as well as for welded materials in order to determine the impact of welding on FCGR. At last but not least, the sensitivity of SIF values to the accuracy of the 3D modelling of the crack surface has been tested. Thus the local roughness of the crack path is seen to drastically impact the out-of-plane shear mode, which is in turn fully consistent with acceleration/deceleration of the crack observed for Ti6242 alloy
Fares, Youssef. "Dimensionnement en fatigue des assemblages boulonnés à l'aide de critères de fatigue multiaxiale." Toulouse, INSA, 2006. http://www.theses.fr/2006ISAT0016.
Повний текст джерелаThe aim of this thesis is the use of multi-axial fatigue criterion in bolted assemblies design. From a comparative analysis of several criterion, we chose those of SINES and DANG VAN that we generalised to limited fatigue life. These criterion require the knowledge of the stress level in the screw at the bottom of its first thread in contact with the nut, where fatigue failure occurs. For this, we used a finite elements model of the bolt. On the other hand, several fatigue tests were undertaken; with the number of cycles to failure related to the stress level at the bottom of threads obtained by simulation, we characterised the multiaxial fatigue behaviour of the tested bolts. Then, the use of these criteria to industrial bolted joints was experimentally validated on a flanged type assembly. To overpass the finite elements model of the bolted joint, we used NEUBER's generalised rule and ESED method to determine the stress level at the bottom of the first thread under a cyclic loading. The fatigue tests were carried on two types of bolts: cold rolled then heated-tempered bolts, and heated-tempered then cold rolled bolts. The improved performance on this last type of bolts has put in evidence the influence of chronology of the different manufacturing operations. This improvement is explained by the residual stresses induced by rolling that we tried to simulate
Attari, Nordine. "Etude en fatigue oligocyclique multiaxiale d'un alliage de magnésium GA3Z1." Vandoeuvre-les-Nancy, INPL, 1991. http://www.theses.fr/1991INPL010N.
Повний текст джерелаPalin-Luc, Thierry. "Fatigue multiaxiale d'une fonte GS sous sollicitations combinées d'amplitude variable." Paris, ENSAM, 1996. http://www.theses.fr/1996ENAM0029.
Повний текст джерелаZine, Adil. "Fatigue multiaxiale des élastomères : vers un critère de dimensionnement unifié." Lille 1, 2006. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2006/50376_2006_128.pdf.
Повний текст джерелаBillaudeau, Thomas. "Fatigue multiaxiale des matériaux à défauts : mécanismes et critère d'endurance." Poitiers, 2002. http://www.theses.fr/2002POIT2326.
Повний текст джерелаThis project aims to formulate a multiaxial fatigue criterion for metallic materials containing defects. An experimental study highlighted the influence of their geometry on the fatigue limit, under tension and under torsion. The observation of the mechanisms revealed the fatigue Stage I part of the cracks at defects, implying the necessary consideration of the creation of cracks in the material slip system. The criterion is defined by the local stress state, by mean of both deviatoric and hydrostatic part of the tensor, together with the gradient of the hydrostatic part. This gradient explains the influence of the defects on the fatigue limit. The criterion has been validated for defects of different morphologies (size and shape) under different loadings (tension, torsion and tension/torsion) and for different materials
Shen, Chen. "Contribution à l’étude du cumul de dommage en fatigue multiaxiale." Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10135/document.
Повний текст джерелаThis work is a contribution to the study of the effect of cumulative damage in multiaxial high cycle fatigue in metallic materials (the aluminum alloy 6082T6). Generally, this effect can be interpreted by different cumulative damage models. In 2003, Mesmacque and Santos Garcia have developed a new damage stress model (DSM), introducing a novel nonlinear damage indicator in the case of uniaxial fatigue. This indicator requires previous knowledge of the Wohler curve and the ultimate tensile strength of the material. The work presented here is an extension of the DSM model to the case of multiaxial fatigue. This extension is made possible with the assumption of multiaxial fatigue criteria: global type (Sines) and critical plane type (Dang Van and Robert) under finite life regime and the implementation of an iteration method in Matlab programming, which provides damage indicators. In particular, it requires no additional parameters besides the uniaxial Wöhler curve, which makes it easy to use. The results of experimental biaxial fatigue tests were obtained with the aid of the multiaxial test platform of our laboratory (four-cylinder modular-implementations platform) and an original test mode based on “modal control”, providing ground for the validation of our model and its comparison against other most current models. An experimental database is available for constant-level and block fatigue loadings using cruciform specimens thinned in the center. In addition, a numerical simulation in Abaqus allowed the analysis of the strain/stress field in the center of the specimen. The simulation results were corroborated using a specimen instrumented with strain gages
ROBILLARD, MARC. "Etude de l'endommagement et de la rupture en fatigue oligocyclique multiaxiale." Paris, ENMP, 1989. http://www.theses.fr/1989ENMP0190.
Повний текст джерелаBonnand, Vincent. "Etude de l'endommagement d'un superalliage monocristallin en fatigue thermo-mécanique multiaxiale." Paris, ENMP, 2006. http://www.theses.fr/2006ENMP1375.
Повний текст джерелаTurbines blades made out of AM1 C1A coated single-crystal superalloy are components subjected to severe loading. One of the objectives of this research was to simulate these thermal and mechanical loads in a controlled manner under laboratory conditions. Another objective was to assess the accuracy of the constitutive equations in non-isothermal multiaxial conditions, as well as the accuracy of the life time prediction model. An axial-torsional Thermo-Mechanical Fatigue test device was developed based upon a particular experimental procedure, consisting of controlling the mechanical strain during thermal cycling (in our case from 650°C to 1100°C). In the case of a torsional loading, the anisotropy of the single crystal leads to heterogeneity of the deformation. This strain heterogeneity can be modelled by 3D Finite Elements simulations. However, it was necessary to develop a specific calculation algorithm in the ZeBuLoN code in order to assure a good correspondence with the thermo-mechanical test. The numerical simulations were carried out with a model of crystalline viscoplasticity. They are in good agreement with the experiments, for various mechanical loadings : the life durations and the localization of damage (crack initiation) were compared successfully with those obtained by a damage model with interaction fatigue-creep-oxidation interaction, except in the case of loading of torsion at high level where the comparison was less convincing. Complementary torsion tests at 950°C were also carried out with a torque control. They have shown a ratchetting phenomenon that was not expected for an alternated loading in torsion. This was modelled successfully by using an asymmetric version of the constitutive equations. The analysis of these tests clearly contradict the predictions of the damage model, in the isothermal case even stronger than for the anisothermal tests
Le, Mire Etienne. "Contributions expérimentales et théoriques à la fatigue multiaxiale des élastomères : Vers un critère cinématique." Electronic Thesis or Diss., Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0021.
Повний текст джерелаFatigue life prediction of elastomers undergoing multiaxial loading conditions is an open problem. The most efficient existing criteria are classically expressed in terms of stress, which necessitates the choice of a hyperelastic model and the determination of its parameters, which are sources of imprecision. The present thesis proposes to tackle the problem through a purely kinematic approach. In this way, several mathematical properties ofthe Hencky strain tensor h are used. On the one hand, two of its invariants (noted K2 and K3) allow the decomposition of the strain into a modeand an intensity, easing its physical interpretation. On the other hand, recent works on tensor decomposition lead to a new mechanical interpretation of this strain measure as a “sum” of elementary transformations. Thanks to K2 and K3, a new method for designing multiaxial fatigue tests is developed and applied to tension-torsion experiments, both in phase and out-of-phase. Moreover, the decomposition of tensor h allows the visualization of deformation cycles in 3D, and lead to a new definition of their mean and amplitude. Finally, a first fatigue criterion is proposed, based on a purely kinematic modelling of crack initiation mechanisms coupling cavitation and extension of a critical plane. It involves a kinematic equivalent of the hydrostatic pressure, derived from the decomposition of h into positive and negative parts. Ultimately, this criterion is applied to the fatigue tests realized in this work, and also to a large database built during the thesis, consisting of more than 350 tension-torsion tests published in the literature
Lacroix, Florian. "Etude du comportement en fatigue des caoutchoucs synthétiques." Tours, 2004. http://www.theses.fr/2004TOUR4060.
Повний текст джерелаThe behaviour of an elastomer being a close function of its service conditions (stress, temperature or the environment), it is very difficult to study its fatigue resistance. This study is focused essentially an crack initiation, a subject seldom studied. The aim of this study, in the industrial context is to increase the fatigue life of a chloroprene elastomer and to identify a mechanical parameter characteristic of fatigue. The second aim is to correlate laboratory specimen behavior with that of real components (tested in special set ups) by means of a finite element simulation. We have identified a scalar parameter, representing the dissipated energy and determined by a visco-hypereleastic constitutive low. Different crack techniques to detect crack initiation were tested and a critical analysis has beeen made on the efficiency of these techniques
Vu, Quoc Huy. "Fatigue polycyclique multiaxiale de l'acier C35 : caractérisation et modélisation des mécanismes d'endommagement." Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aéronautique, 2009. http://tel.archives-ouvertes.fr/tel-00445429.
Повний текст джерелаBennani, Amine. "Elaboration, Comportement et Durée de vie en Fatigue du Caoutchouc Naturel chargé de Silice." Paris, ENMP, 2006. https://pastel.archives-ouvertes.fr/tel-00136825.
Повний текст джерелаNatural rubber has long been reinforced by stiff fillers such as carbon black in order to improve mechanical properties (breaking strength, abrasion, rigidity…). The introduction of silica particles to the library of potential fillers offers new possibilities to further tailor the properties of Natural rubber via blending. Introduce silica instead of carbon black is a challenge in pneumatic industry. Synthetic-based elastomers filled with silica particles decrease in rolling friction of the tires while also retaining a good adherence. The goal of this study is to explore the influence of silica particles one the mechanical behavior, stiffness, strength, hysterisis, fatigue lifetime, of natural rubber. The main purpose is to understand the influence of the morphology of silica (Interaction surfaces between filler with rubber, dispersion with random distribution, chemical activity) on the mechanical behavior and on the fatigue lifetime. Also, Two blends with two different morphology of silica were produced. The both blends were made to obtain similar rheology properties. Experiments investigations were performed to identify the mechanical behavior such as (tension, compression, torsion ,cyclic loading, relaxation tests) and mechanisms of deformation and damage were estimated from uniaxial elongation in combination with in situ SEM micrographs tests. The micro-structure of the blends were studied through SEM observations and uniaxial elongation in combination with in situ X-ray. Theses studies indicate respectively a good dispersion of the filler and a crystallization of soft-segment induced by elongation. Fatigue experimental results with fractographic observations allow to built a new model of lifetime prediction. This model is able to predict the location and orientation of cracks as well as the fatigue lifetime. The life time experiments and numerical tests study shows how the two different silica particles reinforced natural rubber , when subjected to various mechanical loading conditions (uniaxial, hydrostatic, monotonic, cyclic)
Valantin, Chloé. "Compréhension des mécanismes d'endommagement de l'interface textile-caoutchouc." Thesis, Tours, 2014. http://www.theses.fr/2014TOUR4027.
Повний текст джерелаStudied belts undergo complex mechanical stress and thermal variations up to 160°C. To enhance their service life, the interfacial properties between the PA 4, 6 cord, coated with RFL, and the EPDM matrix must be improved. In this study, fatigue tests on belts were stopped after various numbers of cycles in order to characterize the interface between cord and rubber. Electron Microscopy revealed three different mechanisms for mechanical damage: Degradation of the inner cord structure Propagation of fibrillar microcracks at the RFL/rubber interface Appearance of RFL/polyamide microfiber debondings This damage was associated with interfacial hardenings (nanoindentation), viscoelastic properties variations of the structure (DMA) and a decrease in adhesive values (peeling or pulling out). Physicochemical analyses, mainly by Tof-SIMS, enabled to determine interfacial composition and to link its evolution with observed mechanical damage
Raoult, Ida. "Structures élastomères sous chargement cyclique : Comportement – Fatigue – Durée de vie." École polytechnique, 2010. http://www.theses.fr/2010EPXX0090.
Повний текст джерелаThe automotive industry must ensure the service life of numerous rubber components used for anti vibratory purposes. This work aims at proposing a method to predict the fatigue life of a carbon-black reinforced natural rubber structure. The approach proposed here consists in uncoupling the evolution of the mechanics behaviour and damage under cyclic loading. We make the assumption that the behaviour tends to stabilize and that the lifetime, defined as the initiation of a crack, depends only on the mechanical variables in the stabilized state. Upon cyclic loading, elastomers experience a stress-softening phenomenon known as the Mullins’ effect. This phenomenon occurs mostly during the first few cycles, after which the response of the material remains unchanged by additional reloading. We propose a model to represent this stabilized state, supposed to depend only on some cyclic variables. The parameters are the maximum stretches reached in a finite number of material directions, in order to describe the anisotropy induced by the Mullins’ effect. This model is used to analyse a large number of uniaxial and multixial fatigue tests realised with cylindrical dumbbell specimens. We show its ability to take into account the type of control (force or displacement) and the influence of an initial overload. The analysis of the multiaxial data indicates that the maximum principal stress is well correlated with lifetime for all types of solicitations, excepting those which involve multi-plane cumulative damage. A cumulative damage law is proposed to account for these types of loading
BENNEBACH, MOHAMED. "Fatigue multiaxiale d'une fonte gs. Influence de l'entaille et d'un traitement de surface." Paris, ENSAM, 1993. http://www.theses.fr/1993ENAM0021.
Повний текст джерелаBentachfine, Saâdia. "Etude en fatigue oligocyclique multiaxiale en phase et hors phase d'un alliage de magnésium-lithium." Metz, 1993. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1993/Bentachfine.Saadia.SMZ9314.pdf.
Повний текст джерелаThe aim of this thesis is the study of the influence of the out-of-phase on life duration in multiaxial low cycle fatigue of a magnésium-lithium alloy. In first chapter, we expose the state of the art of multiaxial low cycle fatigue of a magnesium-lithium alloy and the different criterion of life prediction existing in this domain. The second chapter will be devoted to the experimental study. In the third chapter, we will present a discussion of experimental results. In the fourth chapter, a metallographic study of the material we have used, we clear us and then give us a physical explication to the differents results we met. We will present in the five chapter, lot models of fatigue prediction of material in multiaxial low cycle fatigue in phase and out-of-phase. At last, a general conclusion will make a balance sheet of this memory
Roux, Clément. "Dimensionnement en fatigue multiaxiale des toiles de roues ferroviaires sous sollicitations multi-paramètres à amplitude variable." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX109/document.
Повний текст джерелаThe main objective of this PHD thesis is to develop a method for the definition of simplified equivalent loads representative of real loads (the severity is equivalent from fatigue phenomenon point of view). This method must be adapted to multi-input problems because loads applied on wheels are multi-dimensional (vertical and lateral loads) and independent. Finally, the thesis also aims to provide a comprehensive approach to fatigue-reliability problem of the wheels, which can be an extension of the stress-strength method for multi-input loads. A fatigue criterion for the railway will is presented and identified using a new test campaign
Klimkeit, Bert. "Etude expérimentale et modélisation du comportement en fatigue multiaxiale d'un polymère renforcé pour application automobile." Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aéronautique, 2009. http://tel.archives-ouvertes.fr/tel-00464186.
Повний текст джерелаFeaugas, Xavier. "Microstructure et modélisation du comportement en fatigue uniaxiale et multiaxiale d'un alliage de titane biphasé." Compiègne, 1994. http://www.theses.fr/1994COMPD772.
Повний текст джерелаChaussumier, Michel. "Un modele statistique de calcul en fatigue multiaxiale pour les pieces mecaniques en acier nitrure." Paris, ENSAM, 1999. http://www.theses.fr/1999ENAM0045.
Повний текст джерелаFlacelière, Laurent. "Contribution a la modélisation du dommage en fatigue multiaxiale d’un acier C36 : confrontation à l’expérience." Poitiers, 2004. http://www.theses.fr/2004POIT2338.
Повний текст джерелаThe basic objective of this thesis is the experimental characterization of deterioration mechanisms for simple (tension and torsion) loading cycles as well as for complex sequential loading programmes. The study of cumulative damage development for corresponding (tension and torsion) loadings blocks is put forward. This experimental investigation is a basis for coupled damage-plasticity mesomechanical modelling of the multiaxial fatigue phenoma. Established within a thermodynamic framework, there are in fact three modular and ascending damage models proposed. The gradual increase in their respective complexity is a consequence of accounting for increasing number of phenomena : nucleation, propagation in mode II, bifurcation, propagation in mode I, combination of the both and finally ruin of the crystalline aggregate. Moreover, by using an approach considering privileged slip direction within the activated system, it is possible to establish a description of damage intensity accounting for multitude of orientations in physical space of the material. A statistical approach is also proposed within the above approach
Gaborit, Pierre. "Unification des modèles d’endommagement de type Lemaitre, pour la fatigue LCF/HCF, multiaxiale et aléatoire." Thesis, Cachan, Ecole normale supérieure, 2015. http://www.theses.fr/2015DENS0041.
Повний текст джерелаThis work presents the proposal of a unifying predictive model to deal with LCF and HCF problems. It is based on a two-scale approach initially developed by Lemaitre. As the damage evolution law is rate written, complexity due to non proportional and random loadings may also be treated. An experimental fatigue campaign of 12 cross shaped samples made of TA6V alloy for aerospace applications is presented. It includes not only proportional and non proportional biaxial tests but also pseudo random loadings. Digital Image Correlation is used to evaluate the local strains from pictures taken in the zone of interest. Loadings are the simulated and both strains and lifetimes are compared to experimental observations. Among the theoretical contributions presented in this work, the main are: - A new kinematic hardening evolution law for the modeling of elasto-plasticity of TA6V alloy under cyclic loadings; - Use of local elastoplastic correction from linear Finite Element Calculation to estimate plastic strains in the structure zone of interests; - Improvements of the micro-plastic yield function to take into account mean stress effect and triaxiality effects in the lifetime prediction in HCF domain; - A unifying method of two damage variables in order to extend the validity domain of the initial model to shorter lifetimes (LCF). As the model is based on a thermodunamical framework for continuum mechanics, several extension are mentioned as future propects
BENTACHFINE, SAADIA Pluvinage Guy. "ETUDE EN FATIGUE OLIGOCYCLIQUE MULTIAXIALE EN PHASE ET HORS PHASE D'UN ALLIAGE DE MAGNESIUM-LITHIUM /." [S.l.] : [s.n.], 1993. ftp://ftp.scd.univ-metz.fr/pub/Theses/1993/Bentachfine.Saadia.SMZ9314.pdf.
Повний текст джерелаAbdelmoumen, Saïd. "Contribution à l'étude des déformations différées sous charge constante de composites ciment-caoutchouc." Amiens, 2009. http://www.theses.fr/2009AMIE0104.
Повний текст джерелаTrabelsi, Mariem. "Propagation de fissures en fatigue oligocyclique multiaxiale à haute température pour le superalliage HAYNES® 188." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM952.
Повний текст джерелаThis study is concerned with the SEMAFOR (ANR-14-CE07-0037) project in collaboration with ONERA, Mines ParisTech,LMT Cachan and Safran. In very high temperature condition, as found for some engine aircraft components, crack couldinitiate near perforated zones. Once a crack is initiated, further degradation by crack growth is the result of a complex setof phenomena: multiaxial fatigue loading, thermal gradients and large scale yielding under oxidizing environment. The purpose of this study is to analyse the fatigue crack growth of the superalloy HAYNES® 188 under such conditions wit hbiaxial tests. The design of an original experiment is a challenging issue to conduct biaxial tests at high temperature. A specific inductor (pancake) was designed to decrease thermal gradient within the gage length. Subsequent thermalfield has been measured using Infra-red thermography. An experimental methodology was developped to ensure a deep analysis of the crack growth. One of our major purpuse is the determination of the experimental fatigue crack growth rate in such conditions. A finite element numerical analysis was achieved using a post-processing methodology based onenergy partition. This model has been successfully validated, at first without crack insertion, for cruciform specimen tests with neither modification of the model constitutive parameters. Using consistent remeshing tools, crack propagation was modeled by explicit introduction of the crack observed experimentally. This approach leads to analyze the mechanical quantities controlling the fatigue crack growth under large scale yielding at high temperature, in order to establish tools for3D modeling of explicit crack propagation
Dubar, Laurent. "Fatigue multiaxiale des aciers. Passage de l'endurance a l'endurance limitee. Prise en compte des accidents geometriques." Paris, ENSAM, 1992. http://www.theses.fr/1992ENAM0019.
Повний текст джерелаSaintier, Nicolas. "Fatigue multiaxiale dans un élastomère de type NR : mécanismes d'endommagement et critère local d'amorçage de fissure." Phd thesis, Paris, ENMP, 2001. https://pastel.archives-ouvertes.fr/tel-00397910.
Повний текст джерелаBennani, Amine. "Elaboration, comportement et durée de vie en fatigue du caoutchouc naturel renforcé de silice." Phd thesis, École Nationale Supérieure des Mines de Paris, 2006. http://tel.archives-ouvertes.fr/tel-00136825.
Повний текст джерелаCe qui leur confère de meilleures propriétés (résistance à la rupture, abrasion, rigidité...). Actuellement, les charges
renforçantes les plus souvent utilisées sont les noirs de carbone. La substitution de cette charge classique par la silice constitue un challenge dans l'industrie pneumatique. En effet, il est admis que la silice diminue la résistance au roulement des pneus, de matrice synthétique, tout en conservant une bonne adhérence. La particularité de cette étude est d'analyser l'influence du renfort par la silice sur le comportement mécanique en endurance du caoutchouc naturel. Son principal objectif est de comprendre l'influence de la morphologie de la silice (surface développée en interaction avec le caoutchouc, dispersibilité, activité chimique) sur le comportement
mécanique et plus spécialement sur la durée de vie en fatigue du caoutchouc naturel ainsi chargé. L'élaboration de deux matériaux permettant d'établir l'influence de la morphologie de la silice constitue une première étape déterminante du travail. Elle se base sur l'incorporation de deux nuances de silice précipitée dans une matrice de caoutchouc naturel pouvant présenter des propriétés rhéologiques similaires. Les essais de caractérisation mécanique (monotones et cycliques) selon différents types de sollicitation (traction, compression, relaxation, traction cyclique, torsion) ainsi que des essais de traction in situ au MEB permettent d'identifier les mécanismes de déformation, de renfort et d'endommagement présents. L'interprétation des résultats de cette campagne expérimentale est basée sur une caractérisation microstructurale approfondie de l'état de dispersion de la silice ainsi que celui de la cristallisation de la matrice en caoutchouc naturel.. Les résultats des essais de fatigue ainsi que les observations microscopiques des mécanismes de propagation des fissures en fatigue permettent d'établir un critère de durée de vie prenant en compte les modes de sollicitation (traction, compression, et torsion). Celui-ci est capable de prévoir la durée de vie ainsi que le lieu d'amorçage des fissures. Il s'avère que, selon le mode de sollicitation appliqué, les propriétés de dispersion de la silice sont plus ou moins importantes dans le renforcement et l'endurance du caoutchouc naturel chargé de silice.
Ce travail fait donc appel à la physico-chimie, à la mécanique et aux observations microstructurales, en allant de l'élaboration des matériaux jusqu'à la modélisation mécanique du comportement et de la durée de vie.
Delahay, Thomas. "Développement d'une méthode probabiliste de calcul en fatigue multiaxiale prenant en compte la répartition volumique des contraintes." Bordeaux 1, 2004. http://www.theses.fr/2004BOR12846.
Повний текст джерелаVidal-Sallé, Emmanuelle. "Prévision de la durée de vie en fatigue multiaxiale sous sollicitations d'amplitude variable à l'aide d'un critère global." Lyon, INSA, 1996. http://www.theses.fr/1996ISAL0012.
Повний текст джерелаThis thesis presents a tool to estimate the fatigue life of a structure subjected to multiaxial variable amplitude stresses. The signed octahedral shear stress is used as a counting variable. Its correct evolution versus time is ensured by the continuity of the motion of the principal frame. That requires a re-organization of principal elements of the stress tensor. To each cycle extracted from the counting variable sequence corresponds cycle. A fatigue criterion based on a global approach gives the fatigue life corresponding any cycle by the way of an implicit method. Three new fittings of the criterion are proposed. Models and assumptions which are necessary to implement the implicit method are given. Their effects on fatigue life assessments are studied. Miner's rule is used for the damage calculation and its linear summation technique. All the steps of the method are implemented in a code. Multiaxial experimental tests under periodical or variable amplitude stress states are used to evaluate the model. As a result predicted fatigue lives are equal to or smaller than experimental lives within a factor from 1 to 5. Finally, the proposed method extends from uniaxial to multiaxial loadings fatigue life prediction without reducing the usual accuracy of fatigue life estimation methods
Rublon, Pierre. "Etude expérimentale multi-échelle de la propagation de fissure de fatique dans le caoutchouc naturel." Ecole centrale de Nantes, 2013. http://www.theses.fr/2013ECDN0003.
Повний текст джерелаThis PhD thesis aims to experimentally characterizethe fatigue crack growth behaviour in natural rubber, and is particularly interested in the neighbourhood of thecrack tip where the well-known phenomenon of straininduced crystallization takes place due to the large strains in this region. The final goal is therefore to explain the outstanding fatigue properties and crack growth resistance of natural rubber which are recognized for a while in literature. On the one hand, fatigue crack growth rate tests are performed to evaluate the influence of various parameters such as the type of elastomer, the carbon-black content and non-relaxing conditions, on the fatigue crack growth resistance. On the other hand, various experimental methods are used at different scales to characterize the fatigue crack tip neighbourhood. First of all, a synchrotron radiation allows us to measure quantitatively the strain-induced crystallization phenomenon at the crack tip using the wide-angle X-ray diffraction method. Moreover, those results are related to strain field measurements obtained by digital image correlation. Besides, an original fatigue experiment performed in a scanning electron microscope enables us to observe in situ the fatigue crack growth mechanisms at the crack tip. Finally, all these experimental results, compared to macroscopic measurements of fatigue crack growth rates in our samples, lead to a discussion about the influence that has the strain-induced crystallization phenomenon on the resistance to fatigue crack growth in natural rubber
Chamat, Abderrahim. "Prévision de la durée de vie en fatigue des roues ferroviaires sous ollicitations multiaxiale proportionnelle et non-proportionnelle." Metz, 2005. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2005/Chamat.Abderrahim.SMZ0509.pdf.
Повний текст джерелаThe experience shows that the fracture of the components or structures in normal working conditions is often due to fatigue. The aim of this works is to propose a criterion which predicts the life duration in endurance fatigue. For this purpose, a signal has been raised during the tests. In order to apply this signal the specimens are extracted from the wheel. Annexe Fatigue Multiaxiale en endurance illimitée 145. Our Instron machine is not predisposed for the realization of this type of loading ; therefore a Labview program has been set which enables to introduce all points of the cycle. The experimental results are compared to the prediction of the various criteria. The application of the various criteria predicted results different from the experimental data. In this perspective, a semi local approach based on the application of the volumetric method has been proposed. Two methods have been proposed to depict the test results in fatigue strength diagram. The first consists in depicting a load factor as a function of the number of cycles to fracture. While the second consists in representing the maximal von Mises stress versus the number of cycles to fracture diagram. Numerous studies showed the influence of the signal in the endurance domain. Experimental results of the present study confirmed these findings. It is noted, the effect of the loading on the life duration becomes negligible from a life duration of 10-7cycles i. E. Low values
Rublon, Pierre. "Etude expérimentale multi-échelle de la propagation de fissure de fatigue dans le caoutchouc naturel." Phd thesis, Ecole centrale de nantes - ECN, 2013. http://tel.archives-ouvertes.fr/tel-00904442.
Повний текст джерелаOstoja-Kuczynski, Élisabeth. "Comportement en fatigue des élastomères : application aux structures antivibratoires pour l'automobile." Nantes, 2005. http://www.theses.fr/2005NANT2153.
Повний текст джерелаThe delivery time for a new car project was previously five years and is now two years. In this context, the numerical simulation should replace experiments in order to sufficiently reduce the design time of new components. Nowadays, simulation of static and dynamic responses of new AVS components is widely used during the design loop, but duration life estimation remains a critical objective for rubber manufactures. In this context, a fatigue life criterion is a necessary pre-requisite to numerically establish the relevance of technical solutions before their experimental validation. In this work, several aspects of fatigue of rubbers are studied : 1 – very long and very short duration life, 2 – reinforcement phenomenon under non-relaxing conditions, 3 – temperature influence and 4 – multiaxiality effects. For each case, propagation law and initiation law are investigated in order to demonstrate that propagation and initiation were drive by similar physical mechanisms
Chamat, Abderrahim Azari Zitouni. "Prévision de la durée de vie en fatigue des roues ferroviaires sous ollicitations multiaxiale proportionnelle et non-proportionnelle." Metz : Université Metz, 2008. ftp://ftp.scd.univ-metz.fr/pub/Theses/2005/Chamat.Abderrahim.SMZ0509.pdf.
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