Дисертації з теми "Caoutchouc – Matériaux – Fatigue"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-21 дисертацій для дослідження на тему "Caoutchouc – Matériaux – Fatigue".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
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
Bennani, 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)
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
Beurrot, 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
Ostoja-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
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
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
Gauchet, Séverine. "Etude de l'influence du type de noir de carbone sur la tenue en fatigue de caoutchouc HNBR." Tours, 2007. http://www.theses.fr/2007TOUR4049.
Повний текст джерелаThe fatigue resistance optimization of the alternator pulley needs to understand damage mechanisms influence on the rubber fatigue behaviour used in mecanical power transmission. Although the toughness of rubber was log time studed, the fatigue of HNBR filled with carbon black is not described in literature. The aim of this work is to understand the influence of filler on theses complex mechanisms through the modifications induiced by filler on the microstructure and dynamical properties. Two damage mechanisms at starting initiate several microcracks which are propagated in rosette forme. Size and number of petals depend on the type of carbon black. This characteristics represent the cracking speed and they describe a mechanisme of crack rotation. The influence of filler on the damage is highlighted by solid NMR H. This original technique proves to be a power technique for studying degradation of rubber having a complex formulation. These results open new propects in order to understand damage mechanisms
Pire, Myriam. "Caoutchouc naturel époxydé et réticulation par les acides dicarboxyliques : chimie, cinétique et propriétés mécaniques." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://pastel.archives-ouvertes.fr/pastel-00732940.
Повний текст джерелаDemassieux, Quentin. "Structural changes in the process zone of a cyclic fatigue crack in filled natural rubber." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066074.
Повний текст джерелаFilled natural rubbers are widely used in structural parts such as tires for their outstanding mechanical properties. Their exceptional behavior is often associated to the ability of natural rubber chains to form a crystalline structure under tension. In the case of cyclic fatigue cracking, the dissipation added through crystallization and melting at the crack tip is often seen as the main reinforcing mechanism that reduces fatigue crack growth. This PhD work focused on all the dissipative mechanisms activated by the strain amplification near a crack tip. An extensive use of X-ray scattering was made to investigate sub-micronic changes in structure (strain-induced crystallization, cavitation, filler network). A study was made in uniaxial tension to understand the effects of material composition and test environment on these structure changes. The effect of filler volume fraction, crosslink density, thermal ageing and test temperature were considered. This study was followed by a complete description of several fatigue crack-tips. Digital image correlation was used to map the strain fields at the vicinity of the cracks, while X-ray mapping of the process zone gave information on the local changes in structure. The cyclic fatigue properties of the materials were then discussed through the knowledge acquired both in uniaxial tension and near crack-tips. It showed that the effect of strain induced-crystallization far outweigh the dissipation added
Balutch, Thomas. "Prise en compte des défauts dans l’analyse du comportement en fatigue d’élastomères EPDM." Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0050.
Повний текст джерелаThe present PhD thesis focuses on the fatigue behavior of EPDM elastomers used in antivibration automotive applications. The objectives are to identify the critical defects with regard to fatigue resistance, to understand the crack initiation and propagation mechanisms around them, to quantify their criticality and finally to understand the origin of the large fatigue lifetime scatter usually observed on these materials. To meet these objectives, the thesis is divided into four parts. First, the bibliographic context and experimental tools are presented. Next, it is proposed to characterize the fatigue properties of the studied elastomers. The two classical approaches of fatigue are then used: lifetime and propagation. Moreover, a procedure for rapid fatigue life characterization using self-heating measurements is developed. Then, fatigue damage at the microscopic scale is analyzed. A fatigue damage scenario for EPDM is then proposed. Furthermore, an original procedure using calibrated defects is developed in order to quantify the influence of defect size. The crack growth rate analysis of small cracks then reveals a "short crack" regime for the studied EPDM. Finally, fatigue lifetimes are linked with the geometric and microstructural features of the critical defects. A clear relationship then appears between the size of the defects, the local strain and the fatigue life, regardless of the type of defect considered (parting line or inclusions). The scatter in fatigue life results can therefore be explained by the natural variations of microstructure between the specimens
Muñoz-Mejia, Luisa. "Étude expérimentale des mécanismes d’endommagement par fatigue dans les élastomères renforcés." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10235.
Повний текст джерелаIn this thesis, we present an experimental study on fatigue crack growth dynamics in a natural rubber filled with silica or carbon black nanoparticles. This work has been developed in an industrial context aiming to transpose the qualities of silica filler on synthetic rubber to natural rubber, which has a strain induced crystallization behavior. The main research objective is to understand the influence of material and test parameters on fatigue fracture of rubber. Crack growth dynamics is followed by video tracking using optical and thermo-graphic cameras. The later allows us to measure the heating build-up of specimens due to cyclic loading. The morphology of rupture surfaces is characterized by post mortem observation (SEM, optical profilometry). The influence of temperature, frequency, kind of filler and filler rate has been studied. Whatever the compound or test conditions, crack growth becomes unstable starting at a certain strain level. This behavior is clearly visible on the curves of tear energy vs. crack growth rate, where two branches of crack velocity appear. In the low velocity branch, the roughness of rupture surfaces is very important because of cavities formation. In the high velocity branch, the morphology of rupture surfaces is characterized by sawtooth striations; their size increase with velocity. We demonstrate that, in contrast with literature data, at least two fatigue cycles are needed to form one striation. The instability occurrence and catastrophic rupture thresholds depend on filler type and test conditions
Narynbek, Ulu Kubat. "Fatigue of HNBR - Effects of formulation and thermal aging." Thesis, Ecole centrale de Nantes, 2018. http://www.theses.fr/2018ECDN0006/document.
Повний текст джерелаThe present PhD thesis is devoted to investigation of fatigue in elastomers, andmore particularly of carbon black-filled hydrogenated nitrile butadiene rubber (HNBR).HNBR is a high performance elastomer classically used for high temperature industrial applications, where high resistance to industrial solvents is also required.The thesis is divided into three main parts.First, major improvements of testing procedures utilized in fatigue life testing ofelastomers are proposed. An original method to prescribe the true stress throughout fatigue experiments is developed; it permits to plot the first “true” Wöhler curve, i.e. true stress vs.number of cycles, for elastomers. Then,statistical tools, widely applied in medical research, are adopted for a comprehensive probabilistic analysis of fatigue life results that exhibit high scatter and censored lifetimes.Second, these novel tools are used to investigate the effect of chemical formulation -acrylonitrile content, percent hydrogenation,and of a composite blend - on fatigue resistance of HNBR at the service temperature of 120 oC. In addition to these fatigue life tests,fatigue crack propagation experiments and microscopic fatigue damage analysis are carried out. Third, the influence of thermal aging on fatigue performances of HNBR is investigated.To this end, two additional fatigue life tests are carried out: simultaneous aging and fatigue experiments, and fatigue experiments on preaged samples.Additionally, strain-induced crystallization in HNBR is studied; for the first time, quantitative relationships between crystallization, strain,and stress are established for unfilled HNBR blends
Broudin, Morgane. "Vieillissement thermo-oxydatif d'un élastomère industriel pour applications automobiles antivibratoires : caractérisations, compréhension, outils de dimensionnement." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0079.
Повний текст джерелаUnder service conditions, many factors are responsible for the evolution of the mechanical properties of rubber parts (temperature, oxygen, mechanical loadings, etc.). Automotive anti-vibration parts using rubber-like materials are usually massive and ageing can therefore lead to heterogeneous properties. To understand the degradation process and especially the effect of oxygen, aerobic and anaerobic ageing conditions have been studied for a wide range of temperatures (from 40°C to 120°C). Numerous samples have been used with different geometries (from thin films to massive structural samples) to ease the interpretation but also to remain as close as possible from the final applications. The mechanical consequences of the ageing have been investigated for both static and fatigue properties throughout a wide experimental database (about 1000 specimens tested in fatigue, for example). The study aims at identifying the physicochemical mechanisms and/or microstructural evolution that cause the processes of degradation and to quantify the consequences on the mechanical behavior and the fatigue properties. These results will provide the necessary elements needed for the integration of thermo-oxidative effects in the fatigue design loop of automotive anti-vibration parts
Glanowski, Thomas. "Compréhension et modélisation des mécanismes élémentaires d’endommagement en fatigue d’élastomères renforcés au noir de carbone." Thesis, Brest, École nationale supérieure de techniques avancées Bretagne, 2019. http://www.theses.fr/2019ENTA0009.
Повний текст джерелаThe fatigue properties of carbon black filled elastomers are strongly related to the inclusions’ population, induced by complex recipes and the successive stages of the manufacturing process (mixing, injection and curing). The improvement of these properties involves at first an ability to describe the statistical features of these inclusions’ population in terms of nature, size, geometry, orientation and spatial distribution. Then, a detailed understanding of the damage mechanisms is required in order to define the mechanical criticality of inclusions according to their characteristics under cyclic loading. This study presents at first the tools developed, based on a detailed analysis of X-ray micro-tomography data. The obtained results on the inclusion’s populations and the damage induced allow highlighting the potential of these tools and their current limits for the studied materials. Atypical inclusions, unknown in the litterature, has been discovered. The cavitation mechanism appears to be the most critical regarding fatigue because it leads to micro-cracks that propagate in the matrix. A comparison of the criticality of the inclusions’ parameters regarding a cavitation criterion is carried out with a parametric study using finite elements simulations. Finally, thermographic measurements at the inclusions’s scale show the additional investiguations needed for a better understanding of the damage mechanisms at this scale
Ruellan, Benoît. "Fatigue of natural rubber at different temperatures : reinforcement due to strain-induced crystallization and modelling the non-linear damage evolution." Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S058.
Повний текст джерелаThe present thesis is dedicated to the investigation of the fatigue behavior of natural rubber (NR) under fatigue loadings. Natural rubbers exhibit extraordinary physical properties, typically the ability to crystallize under tension that is assumed to be responsible for their high fatigue resistance. Strain-induced crystallization (SIC) is a highly thermosensitive phenomenon. Better understanding how SIC reinforces the fatigue life and how temperature affects this property is therefore a key point to improve the durability of rubbers. The present thesis is divided in three parts. The first one is dedicated to the investigation of the fatigue behavior of NR at 23°C and confirms that SIC is responsible for a lifetime reinforcement. Furthermore, a post-mortem analysis is carried to better understand the reinforcement mechanisms. Among the different results obtained, new elements are provided on the fatigue striation phenomenon. The second part addresses the effect of temperature on the SIC-induced reinforcement under non-relaxing loadings. Surprisingly, a lifetime reinforcement still occurs at 90°C although SIC is assumed to be significantly attenuated if not cancelled at elevated temperatures. No SIC effect was observed at 110°C. The third part deals with the construction of a lifetime prediction model for variable loading amplitudes. This model accounts for the lifetime reinforcement due to SIC and the effect of temperature, as well as for non-linear damage
Guo, Qiang. "Réponse thermo-mécanique des élastomères sous chargement cyclique : modélisation constitutive et expérience." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I023/document.
Повний текст джерелаEstablishing the coupling between the different inelastic phenomena, usually appearing together during the cyclic loading history, is an open issue to be addressed. The Phd report is divided into two parts. The first part is focused on filled rubbers. The effects of pre-stretch and filler content on the history-dependent cyclic response of a representative carbon-filled synthetic rubber (SBR) are qualitatively and quantitatively analyzed by using the internal state variable theory. An interpretation of the underlying physical mechanisms is proposed in which two types of dissipative network rearrangements are considered, i.e. recoverable rearrangements inducing viscoelasticity and unrecoverable rearrangements inducing damage. In order to predict the main set of inelastic fatigue effects (fatigue-induced stress-softening and hysteresis along with dissipative heating), we formulate a new thermo-viscoelastic-damage constitutive model based on the internal state variable theory. The proposed constitutive model is implemented into a finite element program and numerical applications on rubber structures are performed. The predictive capabilities of the model are verified by comparisons with our experimental observations. The second part is focused on stretch-induced crystallizable rubbers. We develop a new micro-mechanism inspired molecular chain model to describe the progressive evolution of the crystallinity degree in rubbers and the history-dependent thermo-mechanical response within the context of the thermodynamic framework. In this model, the molecular configuration of the partially crystallized single chain is analyzed and calculated by means of some statistical mechanical methods. Our approach is implemented into the micro-sphere model in the aim to introduce the crystallization-induced anisotropy and dissipation. The proposed constitutive model is then used to discuss some important aspects of the micro-mechanism and the macro-response under the equilibrium state and the non-equilibrium state involved during stretching/recovery/continuous relaxation. The model simulations are also compared to experimental data at different stretch levels and temperatures. Local fields in terms of anisotropy and dissipation are presented on illustrative numerical examples
Poisson, 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 джерелаGillani, Syed Asad Ali. "Degradation of the residual strength of concrete : effect of fiber-reinforcement and of rubber aggregates : application to thin bonded cement-based overlays." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30040.
Повний текст джерелаThis work is devoted to the study of the debonding of thin bonded cement-based overlays from the concrete substrate under mechanical loading. As repair materials, fiber-reinforced and rubbberized cement-based mortars are used. Under these conditions, assessment of durability of the repairs necessarily involves the study of the degradation of the bridging strength under fatigue loading. In this context, tensile fatigue tests controlled by crack mouth opening displacement (CMOD) are conducted on composite specimens in order to establish the degradation law of fiber-reinforced and/or rubberized mortar. The bridging strength decreases with the number of fatigue cycles for the same maximum crack width, whatever the nature of the composite. The maximum cyclic bridging strength degradation occurs in plain mortar. The cyclic bridging strength degradation for large pre-cracked widths is limited for mortar reinforced with metallic fibers. In case of rubberized mortar, cyclic bridging strength degradation is limited at less pre-cracked width values. A combine use of rubber aggregates and fibers in mortar appeared to be a suitable solution to limit the cyclic bridging strength degradation for a wide range of pre-cracked widths. It confers to the composite an interest for durable application such as cement-based thin bonded overlays. Taking into account the main cause of distress in thin bonded cement-based applications i.e. cracking and interface debonding, different surface preparation techniques were evaluated in this research. Among them, the sandblasting one is usually implemented in actual conditions. In order to investigate the structural performance, composite beams consisting of a thin repair layer on top of sandblasted substrates are subjected to three point bending tests (monotonic and fatigue). For monitoring the evolution of cracking in the repair layer and of debonding at interface, digital 3D image correlation technique is used. It emerges as a conclusion that the rubber aggregates incorporation in repair material is helpful to control micro-cracking, which results in the delay of the debonding initiation. Moreover, a fiber-reinforcement of repair material is also helpful to limit the interface debonding propagation by restraining opening of the crack. So, the dual-use of rubber aggregates and fibers in the repair material of thin bonded cement-based overlays can be a suitable solution to delay the debonding initiation and also to limit the interface debonding propagation. This shows that the synergetic effect provided by the combine use of rubber aggregates and fibers remains valid under fatigue loading also. The used rubber aggregates are obtained by grinding end-of-life tyres. In such conditions, the approach brings an added value, the recycling of this industrial by-product being also a contribution to the maintenance of a clean environment. Incidentally, this approach also helps towards the development of a circular economy
Fradet, Clémence. "Caractérisation d’élastomères synthétiques par indentation instrumentée (I.I.T.) : protocoles et applications." Thesis, Tours, 2019. http://www.theses.fr/2019TOUR4014.
Повний текст джерелаInstrumented indentation testing (IIT) is a local method of caracterization which has highlighted a significant potential to probe materials’ behaviors. Nevertheless, for now, its use has been limited to metals, ceramics or more polymers. Thus IIT is rare in literature about mechanics of elastomers, mainly due to their local heterogeneity and viscoelasticity which are responsible for non-negligible experimental bias. The first aim of this thesis is to set up a robust protocol so as to bring relevant responses to practical industrial issues. Plethora of local phenomena in elastomers are serious candidates for the application of this technique. These works deal specifically with the influence of the micro-morphology and the loading-unloading kinematics when indenting a synthetic elastomer. The established protocol has then been used on industrial materials, for aeronautic and automotive uses, so as to probe the effects of a thermal ageing, a mechanical fatigue, different vulcanization rates and interfacial gradients of a polymer-elastomer composite
Nguyen, Trung-Hieu. "Durabilité des réparations à base cimentaire : analyse comparée de l'influence des propriétés mécaniques du matériau de réparation." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/963/.
Повний текст джерелаSubstrate-overlay composites should work monolithically. For this reason, the durability of a cement-based repair relies also on the durability of its bond with the substrate. To improve the durability of repair, it is necessary to prevent the original cause of debonding: cracks through the depth of the overlay. For this the use of a cement composite having an improved strain capacity should be considered as a suitable solution. The aim of this work is to validate this hypothesis. As repair materials, cement-based mortars incorporating low aggregate stiffness and with fibre reinforcement were used. Rubber aggregates obtained from grinding end of life tyres were used thus contributing to the recovery of an industrial byproduct. Stainless and high bond steel fibres were also used. They are effective to restrain the cracking and can be used in aggressive environment. A good synergy between rubber aggregates and fibres reinforcement is demonstrated: rubber aggregates improve the strain capacity of the composite before the macro-cracking localisation and residual post-peak strength due to the fibre reinforcement is not affected. Monotoneous and fatigue bending tests were carried out on specimens repaired by using these mortars. These tests allow the structural response, in particular the interface debonding, to be analysed (the load corresponding to the debonding initiation and debonding propagation). In parallel, a numerical modelling based on finite element method was conducted to simulate the mechanical response of the tested specimens. Comparison between experimental and numerical results shows the relevance of the numerical modeling which is suitable tool that highlights the effect of the restrained length change of the repair material at the interface on the debonding mechanisms. As ultimate findings, this study shows that a positive synergetic effect from rubber aggregate and fibre reinforcement contributes to enhance the durability of bonded cement-based overlays