Letteratura scientifica selezionata sul tema "Simulations de rupture ductile"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Consulta la lista di attuali articoli, libri, tesi, atti di convegni e altre fonti scientifiche attinenti al tema "Simulations de rupture ductile".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Articoli di riviste sul tema "Simulations de rupture ductile"
1
Rahafrooz, M., M. Sanjari, M. Moradi e Danial Ghodsiyeh. "Prediction of Rupture in Gas Forming Process Using Continuum Damage Mechanic". Advanced Materials Research 463-464 (febbraio 2012): 1047–51. http://dx.doi.org/10.4028/www.scientific.net/amr.463-464.1047.
Testo completoAbstract (sommario):
The Continuum Damage Mechanics is a branch of applied mechanics that used to predict the initiation of cracks in metal forming process. In this article, damage definition and ductile damage model are explained, and also ductile damage model is applied to predict initiation of fracture in gas metal forming process with ABAQUS/EXPLICIT simulation. In this method instead of punch, the force is applied by air pressure. In this study, first the ductile damage criterion and its relations are taken into account and, subsequently, the process of gas-aid formation process is put into consideration and ductile damage model for prediction of rupture area is simulated using ABAQUS simulation software. Eventually, the process of formation via gas on the aluminum with total thickness of 0.24 [mm] was experimentally investigated and the results acquired from experiment were compared with relating simulations. The effect of various parameters such as radius of edge matrix, gas pressure and blank temperature has been evaluated. Simulation was compared with experimental results and good agreement was observed.
2
Chowdhury, S. "Finite element simulations of ductile rupture in a constrained metal foil". International Journal of Multiphase Flow 22 (dicembre 1996): 136. http://dx.doi.org/10.1016/s0301-9322(97)88479-0.
Testo completo
3
Chowdhury, S. Roy, e R. Narasimhan. "Finite element simulations of ductile rupture in a constrained metal foil". Materials Science and Engineering: A 191, n. 1-2 (febbraio 1995): 27–37. http://dx.doi.org/10.1016/0921-5093(94)09645-7.
Testo completo
4
Abakumov, A. I., I. I. Safronov, A. S. Smirnov, A. B. Arabey, A. G. Glebov, T. S. Esiev e B. A. Sarychev. "NUMERICAL SIMULATION OF A DROP WEIGHT TEST OF DUCTILE PIPE STEEL". Problems of strenght and plasticity 82, n. 4 (2020): 493–506. http://dx.doi.org/10.32326/1814-9146-2020-82-4-493-506.
Testo completoAbstract (sommario):
The processes in the metal sample of a supply pipeline realized under drop-weight tests (DWT, or DWTT according to ASTM) are studied. DWT is a proof test of the pipeline metal that should ensure high resistance of the pipeline against extensive destruction. Numerical simulation of DWT with the steel sample of full thickness was performed; the steel had К65 strength grade. Parallel finite-element computer code DANCO developed in RFNC-VNIIEF was used for simulations. A detailed description of the rupture formation process required a fine-enough mesh and a supercomputer. To carry out the numerical simulation of the process, the constants of the deformation diagram were used, obtained on the basis of static and dynamic tensile tests of samples at room temperature. A modified Gurson–Tvergaard–Niedelman (GTNm) model for macro-viscous steel destruction (ductile failure) was used to describe the strain and the destruction of the metal. The modification makes it possible to describe direct and oblique cuts and their combinations in case of ductile failure of small-size objects (rods, plates, shells). The calculated dependences of the movement of the crack tip on the movement of the load and the resistance force of the sample on the movement of the crack tip are presented. We have got a good agreement between the computations and experimental data with regard to the “force–displacement” strength parameter, the deformed profiles and macro-geometry of the ruptured sample after the tests. The computation results reveal the mechanics of the crack origination, start and propagation in the sample, describe the plastic-flow energy distribution in the process of dynamic destruction. The results of the work can be used in the development of the requirements and of the implementation conditions of the “tooled” DWT, and for numerical simulation of the extensive destruction at the main pipeline.
5
Bernatowska, Edyta, e Lucjan Ślęczka. "Experimental and Numerical Investigation into Failure Modes of Tension Angle Members Connected by One Leg". Materials 14, n. 18 (7 settembre 2021): 5141. http://dx.doi.org/10.3390/ma14185141.
Testo completoAbstract (sommario):
This paper presents the results of experimental and numerical tests on angle members connected by one leg with a single row of bolts. This study was designed to determine which failure mode governs the resistance of such joints: net section rupture or block tearing rupture. Experimental tests were insufficient to completely identify the failure modes, and it was necessary to conduct numerical simulations. Finite element analysis of steel element resistance based on rupture required advanced material modelling, taking into account ductile initiation and propagation of fractures. This was realised using the Gurson–Tvergaard–Needleman porous material model, which allows for analysis of the joint across the full scope of its behaviour, from unloaded state to failure. Through experimental testing and numerical simulations, both failure mechanisms (net section and block tearing) were examined, and an approach to identify the failure mode was proposed. The obtained results provided experimental and numerical evidence to validate the strength function used in design standards. Finally, the obtained results of the load capacity were compared with the design procedures given in the Eurocode 3′s current and 2021 proposed editions.
6
Troufflard, Julien, Guillermo Requena, Sandrine Thuillier e Éric Maire. "Ductile Damage in Tension and Bending for DP980 Steel Sheets". Key Engineering Materials 554-557 (giugno 2013): 110–17. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.110.
Testo completoAbstract (sommario):
The mechanical behavior of DP980 steel sheets of 1.7 mm thickness has been investigated with both tensile and bending tests. Free bending tests were performed on square samples of 60mm side. The bending tool has a sharp radius of around 0.4 mm and the sample simply lies on two rollers. Scanning electron micrography observations were performed in order to check the occurrence of cracks, that indicate the onset of rupture in bending. Moreover, X-ray microtomography observations were performed on smooth and notched tensile specimen, with a specific small-size geometry, and bending specimen. Maximum void volume fractions of 1.5 10-3were recorded and the influence of the triaxiality ratio was investigated, by changing the notch radius. In the case of bending, samples were cut in the bent area and void volume fraction distribution was analyzed along the sheet thickness. Material parameters for Gurson-Tvergaard-Needleman (GTN) model, associated with isotropic hardening and von Mises yield criterion, were identified from the tensile tests. Inverse identification was performed over the different sample geometries, showing that GTN model can not capture the triaxiality ratio influence. Finite element simulations of the bending test were then carried out, in order to compare experimental and predicted void volume fractions in the sheet thickness.
7
Pradeau, A., Sandrine Thuillier e Jeong Whan Yoon. "Bending Behavior to Fracture of an Aluminium Alloy Involving Pre-Strain". Key Engineering Materials 725 (dicembre 2016): 495–501. http://dx.doi.org/10.4028/www.scientific.net/kem.725.495.
Testo completoAbstract (sommario):
The work associated to this abstract is focused on the modelling of an aluminium alloy under the shape of sheet. It characterizes the mechanical behaviour up to rupture of an AA6016 alloy, taking into account the anisotropy and the hardening of the metal. The mechanical tests on which the model is based on consist of uniaxial tension, simple shear and hydraulic bulging performed at room temperature up to rupture, except for the simple shear. The numerical model is constituted of three parts. The choice of the model is suited for ductile fracture and allows for high flexibility, thanks to a total of 21 material parameters. The material parameter identification is realised through an inverse methodology. The objective of such an approach is to minimize iteratively the gap between the experimental and numerical outputs. Validation of the results is then done with the help of bending tests. The bending tests are performed with and without pre-strain in tension prior to the air-bending. Different amplitudes of pre-strain allows to reach rupture or not in bending, thus giving the possibility to find the value of the parameter controlling the non-linear accumulation of the damage. The correlation between experiments and simulations is proved to be successful and gives a very good representation of the mechanical behaviour of the aluminium alloy studied.
8
Foroozmehr, Fayaz, e Philippe Bocher. "On the ductile rupture of 13% Cr-4% Ni martensitic stainless steels". International Journal of Fracture 224, n. 1 (23 aprile 2020): 67–82. http://dx.doi.org/10.1007/s10704-020-00446-2.
Testo completo
9
Fadly, Muhammad Syaiful, Anindito Purnowidodo e Putu Hadi Setyarini. "Karakteristik Fiber Metal Laminate Akibat Beban Impak Balistik Dari Peluru Kaliber 9 mm Full Metal Jacket (FMJ)". Jurnal Rekayasa Mesin 12, n. 1 (31 maggio 2021): 103. http://dx.doi.org/10.21776/ub.jrm.2021.012.01.12.
Testo completoAbstract (sommario):
<p class="Abstract"><span lang="EN-GB">Estimated damage levels from ballistics impact zone provide valuable information to make bulletproof materials more effective. Therefore, this study aims to determine the impact of ballistics including hole shape, hole depth, macro, and microstructure on fiber metal laminate. The characteristics of ballistics impact for each configuration target is obtained from experiment and comparison based on simulations with finite element method. Test experiments used short-barreled fire guns at a distance of 5 meters with a normal attack angle based on the National Institute of Justice standard. Simulation with Johnson-Cook plasticity models for aluminum plate and orthotropic material model for kevlar/epoxy. The experiment and simulation results showed that the projectile is able to perforate the first layer (aluminum plate) and the second layer (Kevlar/epoxy) while the last layer (backplate) is deformed to form a bulge. The aluminum plate is perforated by the failure of petaling formation on the backside and spread of dimple fracture around the area of the petal which indicates ductile fracture while kevlar/epoxy is perforated by projectile with failure of fiber fracture on primary yarn, fiber pull-out, fiber stretching and fiber rupture.</span></p>
10
Orlov, O., Éric Maire, Jérôme Adrien, Michael J. Worswick e David J. Lloyd. "Application of the Three-Dimensional Damage Percolation Model and X-Ray Tomography for Damage Evolution Prediction in Aluminium Alloys". Materials Science Forum 519-521 (luglio 2006): 1011–16. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.1011.
Testo completoAbstract (sommario):
A three-dimensional damage percolation model, which captures the effect of microstructural heterogeneity on damage evolution, has been developed to model damage initiation and propagation in materials containing second phase particles. It considers the three phenomena preceding ductile rupture of the material: void nucleation, growth, and coalescence. Threedimensional X-ray tomography is used to obtain measured three-dimensional second phase particle distributions in aluminum alloy sheet. Material damage evolution is studied within a tensile test simulation and compared to measured damage from an in situ tensile test utilizing X-ray tomography. Experimental and simulation results for material damage initiation and evolution are in good agreement.
Tesi sul tema "Simulations de rupture ductile"
1
Buljac, Ante. "Compréhension, observation et quantification des mécanismes de rupture ductile par imagerie 3D". Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN036/document.
Testo completoAbstract (sommario):
Au cours des dernières décennies, des efforts importants ont été menés dans la modélisation des processus de rupture ductile entraînant des progrès substantiels. Cependant, la compréhension complète des mécanismes de rupture ductile dans des états de contraintes spécifiques demeure une question ouverte. Ceci est dû au manque de bases des données expérimentales et à la non validation des modèles pour ces conditions de chargement. Dans ce travail, les acquisitions de données sont principalement obtenues en utilisant la laminographie, ce qui rend possible l'imagerie de régions d'intérêt d'échantillons plats. L'utilisation d'éprouvettes larges (et minces) permet de générer différents états de contraintes et des conditions aux limites pertinentes pour l'ingénierie, qui ne pouvaient pas être évaluées jusqu'à présent en trois dimensions et en essais in-situ à des échelles micrométriques. La corrélation d'images volumiques (DVC) est utilisée pour mesurer les champs de déplacement à l'intérieur des échantillons en acquérant des images de laminographie 3D. Deux classes de matériaux représentatives de deux modes génériques de rupture ductile ont été examinées, à savoir les alliages d'aluminium (rupture par instabilité) et la fonte à graphite sphéroïdal (rupture par croissance de vide et coalescence).L'observation de la microstructure et les interactions déformations-endommagement pour différentes géométries d'échantillons et pour différents niveaux de triaxialité des contraintes associés ont été étudiées pour des alliages d'aluminium à une résolution micrométrique. De plus, un cadre combiné numérique-expérimental (DVC-FE) est introduit pour valider les simulations numériques à l'échelle microscopique pour la fonte à graphite sphéroïdal. Les simulations par éléments finis (FE), qui représentent la microstructure des matériaux étudiés, sont conduites avec des conditions aux limites de Dirichlet extraites des mesures DVC. Enfin, le cadre DVC-FE a été amélioré et utilisé comme une procédure d'identification intégrée pour l'étude du comportement élasto-plastique de la matrice ferritique de la fonte, non seulement en termes de champs cinématiques induits par la microstructure aléatoire, mais aussi avec les niveaux de charge globauxIn the last few decades significant efforts have been made in modeling ductile failure processes resulting in substantial progress. However, the full understanding of ductile failure mechanisms under specific stress states still remains an open question. This is partly due to missing experimental data and validation of models for such loading conditions.In this work, data acquisitions are mainly obtained by using laminography, which makes the imaging of regions of interest in flat samples possible. The use of large (and thin) specimens allows various stress states and engineering-relevant boundary conditions to be generated, which could not be assessed in three dimensions and in-situ at micrometer scales before. Digital Volume Correlation (DVC) is used for measuring displacement fields in the bulk of samples by registering 3D laminography images. Two material classes that are representative of two generic modes of ductile failure have been examined, namely, Al-alloys (failure by instability) and cast iron (failure by void growth and coalescence). The observation of microstructure and strain-damage interactions at micrometer resolution for various specimen geometries and associated levels of stress triaxiality are studied for Al-alloys. Additionally, a combined computational-experimental (DVC-FE) framework is introduced to validate numerical simulations at the microscopic scale for nodular graphite cast iron. Finite Element (FE) simulations, which account for the studied material microstructure, are driven by Dirichlet boundary conditions extracted from DVC measurements.Last, the DVC-FE framework is upgraded to an integrated identification procedure to probe elasto-plastic constitutive law of the cast iron ferritic matrix not only in terms of kinematic fields induced by the random microstructure but also by overall load levels
2
Forster, Charles. "Contribution à l'étude de la rupture ductile des structures élastoplastiques". Compiègne, 1995. http://www.theses.fr/1995COMPD784.
Testo completoAbstract (sommario):
L'objectif de ce travail est de simuler la ruine des structures élastoplastiques ductiles. Dans une première partie, on présente un modèle élastoplastique endommageable en transformations finies. Écrit dans le cadre de la thermodynamique des milieux continus et de la mécanique de l'endommagement continu, il s'appuie sur une hypothèse d'équivalence en énergie totale pour définir les variables effectives et permet de décrire des écrouissages isotropes et cinématiques non-linéaires. En deuxième partie, on adapte et développe un programme informatique permettant de simuler la ruine des structures. Il s'appuie sur une formulation implicite et incrémentale du problème. L'intégration des équations différentielles fortement non-linéaires de la relation de comportement est particulièrement développée. Des exemples sont traités en troisième partie. Ils démontrent la capacité de l'approche à décrire la rupture ductile des structures, et à capter les phénomènes de localisation dûs au dommage. En quatrième partie, on développe de manière succincte les aspects théoriques lies aux problèmes de localisation.
3
Taherzadehboroujeni, Mehrzad. "Lifetime Estimation for Ductile Failure in Semicrystalline Polymer Pipes". Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/91901.
Testo completoAbstract (sommario):
The aim of this study is to develop a combined experimental and analytical framework for accelerated lifetime estimates of semi-crystalline plastic pipes which is sensitive to changes in structure, orientation, and morphology introduced by processing conditions. To accomplish this task, high-density polyethylene (HDPE) is chosen as the exemplary base material. As a new accelerated test protocol, several characterization tests were planned and conducted on as-manufactured HDPE pipe segments. Custom fixtures are designed and developed to admit uniaxial characterization tests. The yield behavior of the material was modeled using two hydrostatic pressure modified Eyring equations in parallel to describe the characterization test data collected in axial tension and compression. Subsequently, creep rupture failure of the pipes under hydrostatic pressure is predicted using the model. The model predictions are validated using the experimental creep rupture failure data collected from internal pressurization of pipes using a custom-designed, fully automatic test system. The results indicate that the method allows the prediction of pipe service lifetimes in excess of 50 years using experiments conducted over approximately 10 days instead of the traditional 13 months. The analytical model is joined with a commercial finite element package to allow simulations including different thermal-mechanical loading conditions as well as complicated geometries. The numerical model is validated using the characterization test data at different temperatures and deformation rates. The results suggest that the long-term performance of the pipe is dominated by the plastic behavior of the material and its viscoelastic response is found to play an insignificant role in this manner. Because of the potential role of residual stresses on the long-term behavior, the residual stress across the wall thickness is measured for three geometrically different HDPE pipes. As expected, the magnitude of tensile and compressive residual stresses are found to be greater in pipes with thicker walls. The effect of the residual stress on the long-term performance of the pipes is investigated by including the residual stress measurements into the numerical simulations. The residual stress slightly accelerates the failure process; however, for the pipe geometries examined, this acceleration is insignificant.Doctor of Philosophy
The use of plastic pipes to carry liquids and gases has greatly increased in recent decades, primarily because of their moderate costs, long service lifetimes, and corrosion resistance compared with materials such as corrugated steel and ductile iron. Before these pipes can be effectively used, however, designers need the capability to quickly predict the service lifetime so that they can choose the best plastic material and pipe design for a specific application. This capability also allows manufacturers to modify materials to improve performance. The aim of this study is to develop a combination of experiments and models to quickly predict the service lifetime of plastic pipes. High-density polyethylene (HDPE) was chosen as the plastic material on which the model was developed. Several characterization tests are planned and conducted on as-manufactured HDPE pipe segments. The yielding behavior of the material is modeled and the lifetime predictions are evaluated. The predictions are validated by experimental data captured during pipe burst tests conducted in the lab. The results indicate that the method allows the accurate prediction of pipe service lifetimes in excess of 50 years using experiments conducted over approximately 10 days instead of the traditional 13 months, resulting in significant savings in time (and consequently costs) and making it possible to introduce new materials into production more rapidly.
4
Chen, Youbin. "Modélisation de la rupture ductile par approche locale : simulation robuste de la déchirure". Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM038/document.
Testo completoAbstract (sommario):
Cette étude a pour objectif principal d’établir une stratégie de modélisation robuste, fiable et performante pour décrire des propagations de fissures d’échelle centimétrique en régime ductile dans des composants industriels. Le modèle d’endommagement de GTN écrit en grandes déformations est utilisé pour modéliser l’endommagement ductile. Ce modèle conduit généralement à une localisation de la déformation, conformément à l’expérience. L’échelle caractéristique de ce phénomène est introduite dans les équations de comportement via l’adoption d’une formulation non locale.Sur le plan numérique, ce modèle non local rend bien compte de la localisation dans une bande d’épaisseur donnée lorsqu’on raffine suffisamment le maillage. Par ailleurs, le problème de verrouillage numérique associé au caractère initialement isochore de la déformation plastique est limité en utilisant une formulation à base d’éléments finis mixtes. Enfin, la distorsion des éléments totalement cassés (i.e. sans rigidité apparente), qui pourrait nuire à la bonne convergence des simulations numériques, est traitée par une régularisation viscoélastique.L’ensemble de ces ingrédients sont appliqués pour simuler la propagation de fissure dans un milieu infini plasticité confinée), de sorte à établir un lien avec les approches globales en J-Δa. L’émoussement, l’amorçage et la (grande) propagation de fissure sont bien prédits. Le modèle est également appliqué à une tuyauterie métallique testée en grandeur réelle dans le cadre du projet européen Atlas+. Après une phase d’identification des paramètres sur éprouvette, les réponses globales et locales d’autres éprouvettes et du tube sont confrontés aux résultats expérimentaux. Ces résultats illustrent le degré de robustesse, de fiabilité et de performance qu’on peut attendre du modèleThe major goal of this work is to establish a robust, reliable and efficient modeling technique so as to describe ductile tearing over a distance of several centimeters in industrial cases. The GTN damage model expressed in the context of finite strains is chosen to model ductile damage. Generally, the model leads to strain localization in agreement with experimental observations. The characteristic length scale of this phenomenon is introduced into the constitutive equations through the use of a nonlocal formulation.On a numerical ground, the nonlocal model controls the width of the localization band as soon as the mesh is sufficiently refined. Besides, the issue of volumetric-locking associated with plastic incompressibility is handled using a mixed finite element formulation. Finally, the distortion of broken elements (i.e. without any stiffness), which may affect the computational convergence of numerical simulations, is treated using a viscoelastic regularization.The improved GTN model is applied to simulate crack propagation under small-scale yielding conditions, so as to establish a relation with the global (J-Δa) approach. Crack tip blunting, crack initiation and (large) crack propagation are well captured. The model is also applied to a full-scale metallic pipe in the framework of the UE project Atlas+. After a phase of parameter calibration based on the experimental results on some small specimens, the global and local responses of other small specimens and of the full-scale pre-cracked pipe are compared with the experimental results. The results illustrates the robustness, the reliability and the efficiency of the current model
5
Benzerga, Ahmed Amine. "Rupture ductile des tôles anisotropes. Simulation de la propagation longitudinale dans un tube pressurisé". Paris, ENMP, 2000. http://www.theses.fr/2000ENMP1067.
Testo completoAbstract (sommario):
Les aciers à usage gazier sont en général ferrito-perlitiques. En particulier, les tôles laminées présentent une anisotropie de plasticité de nature cristallographique et une anisotropie de rupture. La phénoménologie de l'endommagement ductile révèle une anisotropie initiale liée à la forme des inclusions MnS et une anisotropie induite qui traduit l'évolution de la forme des cavités et/ou de leur orientation. Trois modes de coalescence sont observés: la striction interne, la coalescence en bande et la coalescence en "chapelet". Ce dernier mode est observé en traction selon la direction de laminage. La ccalescence en bande est favorisoe par la rotation des cavités, en traction hors-axes. La propagation fait intervenir essentiellement le mode de coalescence par striction interne. Cependant le mécanisme de propagation change en fonction de l'état de contrainte et du confinement plastique. La modélisation s'inscrit dans un cadre micromécanique. L'anisotropie de plasticité est introduite en étendant l'analyse de Gurson à des matériaux orthotropes obéissant au critère de Hill. Ensuite, la forme des cavités est introduite via le modèle de Gologanu-Leblond. La coalescence par striction interne est modélisée en utilisant un critère de charge limite. Pendant le régime de post-coalescence, la surface de charge est donnée par ce dernier critère, et l'évolution des paramètres internes est déduite d'une cinématique propre au mode de déformation localisé. Le modèle, implanté dans le code ZéBuLoN, est utilisé pour prédire la rupture des barreaux entaillés. Comme le modèle n'utilise pas de paramètre ajustable, une analyse inclusionnaire est nécessaire afin d'estimer la fraction volumique, la forme et l'espacement entre inclusions. Une deuxième application discute le mode de rupture en déformation plane. Les résultats obtenus suggèrent un effet coujugué de l'anisotropie de plasticité et de la courbure de la surface de charge valable en post-coalescence.
6
Bude, Jérémie. "Ductile fracture simulation using the strong discontinuity method". Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2243/document.
Testo completoAbstract (sommario):
Dans un contexte d’évaluation de la criticité des chargements, les travaux de thèse ont les objectifs suivants : prendre en compte les phénomènes sous-jacents à le rupture ductile : les phénomènes de dissipation volumique (plasticité et endommagement) et surfaciques (fissuration). On s'intéresse également à régulariser la solution vis-à-vis du maillage, à prédire le phénomène de transition de mode de rupture plan vers un mode de propagation oblique observé pour certains essais. La méthode utilisée est basée sur la méthode des discontinuités fortes. Un des enjeux majeurs de ces travaux est d’étendre son champ d'application au cadre de la modélisation de la rupture ductile, notamment en présence de plasticité et d'endommagement dans le volume. Une première partie des travaux est consacré à l'établissement d'un modèle en hypothèse de petites déformations, avec un modèle matériau de plasticité et d'endommagement couplé de Lemaitre pour le volume et un modèle cohésif endommageable pour le comportement surfacique. Les deux modes de rupture I et II ont été considérés dans les essais numériques. Des résultats montrant les capacités de régularisation de la méthode employée ont été présentés pour divers essais. Une seconde partie des travaux a été consacré à la formulation d'un modèle en hypothèse de grandes transformations, avec également des résultats probants en termes de régularisation de la dépendance à la taille de maille. Les deux éléments présentés ont été implémentés en formulation implicite et explicite, dans FEAP (Finite Element Analysis Program), logiciel académique développé à UC Berkeley par Taylor, et plus récemment dans le logiciel de calcul Eléments Finis AbaqusIn the context of loadings criticality analysis, the thesis work have the following objectives : to take into account the underlying phenomena to ductile fracture : the volumetrie (plasticity and damage) and surfacic (fracture) dissipativ mechanisms. We also aim at regularizing the solution with regards to meshing, predicting the transition from a straigh crack propagation to a slant fracture mode observed for certain tests. The chosen method relies on the stron discontinuity method. One of the major challenges of this work is to extend its framework to the ductile fractur modeling framework, by accounting for plasticity and damage in the bulk. The first part of this work is dedicated to th establ'ishment of a model in small strain hypothesis, with a material model that takes into account coupied plasticity an damage in the QUik and a damageable model for the cohesive surfacic behavior. Both modes 1 and Il have been taken int) account in thnumerical examples. Results attesting the regularizing capabilities of the method are presented fo different tests. The second part of this work is dedicated to the formulation of a finite strain mode!, and results showin the good regularizing capabilities of the method are also shown. Both elements have been implemented in FEAP (Finit Element Analysis Program), an academie software developed at UC Berkeley by Taylor, and more recently in the finit element software Abaqus
7
Bron, Frédéric Charles André. "Déchirure ductile des tôles minces en alliage d'aluminium 2024 pour application aéronautique". Paris, ENMP, 2004. http://www.theses.fr/2004ENMP1207.
Testo completoAbstract (sommario):
L'objectif de ce travail est la simulation par éléments finis de la déchirure ductile des tôles minces en alliage d'aluminium 2024. La méthode est basée sur l'approche locale de la rupture. Les observations métallographiques indiquent deux mécanismes de rupture. Si la pression hydrostatique est élevée, la rupture intervient par striction interne. Dans le cas contraire, la rupture intervient par localisation de la déformation en bande à 45 degrés. Dans les éprouvettes de fissuration Kahn et M(T), les mécanismes de rupture sont identiques. Les simulations sont basées sur une extension du modèle de Rousselier incluant une représentation de l'anisotropie plastique et de la germination de porosités. Un nouveau critère de plasticité anisotrope est spécifiquement développé. Il s'agit d'une extension du critère de Karafillis et Boyce (1993). Le modèle est appliqué à deux nuances dont la teneur en particules intermétalliques est différente. Les paramètres sont ajustés sur de petites éprouvettes pour le matériau à haute pureté. La transférabilité est vérifiée sur les grands panneaux M(T). Le transfert vers le matériau ayant la plus forte teneur en particules intermétalliques est fait en modifiant la taille de maille dans le même rapport que l'espacement inter-particules. Le modèle est utilisé comme un outil numérique afin d'étudier les effets de la loi d'écrouissage, d'une pré-traction ou de l'anisotropie plastique sur la résistance à la propagation de fissure. Il est alors possible de proposer des voies d'amélioration du matériauThe purpose of this work is to develop a finite element simulation of ductile tearing of thin sheets in 2024 aluminum alloy. The method is based on the local approach to fracture. Metallurgical observations indicate two rupture mechanisms. If hydrostatic pressure is high, rupture arises by internal necking. In the opposite case, rupture arises by localization of deformation into a 45 degree slanted band. In Kahn and M(T) cracking samples, rupture mechanisms are identical. The simulations are based on an extension of the Rousselier model which includes the description of plastic anisotropy and void nucleation. A new anisotropic yield function is specifically developed. It is an extension of the yield function of Karafillis and Boyce (1993). The model is applied to two grades which have different volume fractions of intermetallic particles. The parameters are adjusted in the case of the high purity material on small specimens. The transferability is checked on large M(T) panels. The transfer to the material containing the highest amount of intermetallic particles is made by modifying the mesh size according to the ratio of the particle mean spacing. The model is used as a numerical tool to investigate the effects of plastic hardening, prestraining and plastic anisotropy on crack growth resistance. It is then possible to give guidelines for material improvement
8
Dorothy, Hannah Lois. "Modélisation numérique de la rupture ductile dynamique par cisaillement adiabatique et micro-endommagement couplés". Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30176/document.
Testo completoAbstract (sommario):
Les matériaux à haute résistance, notamment les aciers et les alliages à base d'aluminium et de titane, sont largement utilisés dans l'aéronautique comme matériaux structuraux et de protection. Dans le cas de surcharges accidentelles impliquant des vitesses de chargement élevées et des conditions quasi adiabatiques, ces matériaux sont souvent sensibles au cisaillement adiabatique par bande. Les bandes de cisaillement adiabatique (BCA) sont des zones étroites de cisaillement intense qui résultent d'une instabilité thermomécanique et qui conduisent à une rupture prématurée du matériau. À un stade avancé du processus de localisation, des micro-cavités (MCs) ont été observées dans les BCAs. Ces MCs peuvent coalescer pour former des fissures et mener à la rupture de la structure. Ainsi, les mécanismes couplés d'ASB+MC agissent comme un précurseur à la rupture catastrophique et il est par conséquent important de modéliser numériquement leurs effets dans des structures soumises à des sollicitations à haute vitesse. Les BCAs apparaissent aussi dans certaines applications industrielles, telles que l'usinage à grande vitesse, où elles favorisent le festonnement du copeau. Un postulat de grande échelle est appliqué ici où la longueur caractéristique du volume élémentaire représentatif (VER) est plus grande que la largeur de bande, et non l'inverse comme fait communément. L'objectif du travail présenté est d'enrichir un modèle décrivant les effets des BCAs en prenant en compte les conséquences de l'endommagement par MC dans le processus progressif de la rupture. Les effets des BCAs et des MCs sur la réponse du VER sont doubles : cinématique, à savoir une déviation progressif de l'écoulement plastique dans le plan de la bande décrite via des gradients de vitesse induits par les BCAs et par les MCs; et matériel, à savoir une dégradation anisotrope des modules élastiques et plastiques décrite via des variables tensorielles d'ordre deux de détérioration induite par les BCAs et par les MCs. L'amorçage des BCAs est déterminé à partir d'une analyse linéaire de stabilité et celui des MCs par une valeur critique du taux de restitution d'énergie local. L'intérêt de ce modèle avancé est démontré par comparaison avec un modèle orienté application du type (1-D) où D est une variable de détérioration isotrope. Le modèle enrichi ASB+MC est implémenté comme matériau utilisateur dans le code de calculs commercial par éléments finis LS-DYNA. [...]High strength metallic materials, notably steel and light-weight titanium and aluminium alloys, are widely used in aeronautical and other structures. In case of accidental overload involving high strain rates and quasi adiabatic conditions, these materials are often susceptible to adiabatic shear banding. The adiabatic shear bands (ASB) are intense shear localisation zones resulting from thermomechanical instability and provoking premature material failure. At an advanced stage of the localisation process, the ASBs have been shown to contain micro-voids (MV) which may coalesce to form cracks and ultimately lead to the fracture of the structure. Thus the coupled mechanisms of ASB+MV act as a precursor to catastrophic failure and it is consequently crucial to numerically model their formation and effects when dealing with structures submitted to high loading rates. The ASBs are also observed in industrial applications such as high speed machining where their formation favours the chip serration. A large scale postulate is used herein to obtain a global insight into the structural material response. The shear band cluster is indeed contained/ embedded within the representative volume element (RVE), and not the opposite as usually considered. The objective here is to enrich a model describing the ASB effects by taking into account the consequences of the micro-voiding within the progressive failure process. The effects of ASB and MV initiation and evolution on the RVE (material point) response are double: kinematic, namely a progressive deviation of the plastic flow in the band plane described via specific ASB and MV induced velocity gradients; and material, namely a progressive anisotropic degradation of the elastic and plastic moduli described via ASB and MV induced second order tensor deterioration variables. The ASB onset criterion is derived from the linear perturbation analysis and the MV is activated using a critical value for the local energy release rate. The interest of this advanced constitutive model is emphasised by comparison with an application oriented (1-D) model where D is a scalar damage variable. [...]
9
Douziech, Jean-Luc. "Comportement et rupture d'un alliage d'aluminium silicium, AS7G03 : application : modélisation du comportement dynamique de support moteur,simulation de crash test". Châtenay-Malabry, Ecole centrale de Paris, 1997. http://www.theses.fr/1997ECAP0638.
Testo completoAbstract (sommario):
Le comportement dynamique de pièces de liaison entre les éléments mécaniques et la structure influe beaucoup sur le déroulement d'un choc (intrusion d'éléments dans l'habitacle, décélération au niveau des occupants). Afin d'optimiser les fonctions de ces pièces, on cherche à modéliser leur comportement lors d'un choc. L’élément qui nous intéresse relie la structure au groupe de moto-propulsion. Ces pièces, supports de moteur, sont de plus en plus souvent réalisées en alliages d'aluminium moulé. L’objectif de cette étude est la modélisation du comportement d'un support moteur sous sollicitation dynamique. Pour ce faire, il est nécessaire de bien connaitre le comportement et la rupture du matériau, l'AS7G03 qui est un alliage d'aluminium - silicium moulé. Nous avons examine l'influence de la composition chimique de l'alliage et notamment du fer sur le comportement du matériau. La structure de la pièce considérée étant complexe, les vitesses de refroidissement varient d'un point à l'autre. Il est donc important d'étudier l'influence de la vitesse de solidification sur la microstructure du matériau et donc sur ses propriétés mécaniques. En plus des paramètres de fabrication, nous avons étudié des paramètres mécaniques, à savoir l'effet des chargements multiaxiaux ainsi que l'effet de la vitesse de chargement. Pour connaitre l'influence de chargements multiaxiaux, nous avons réalisé des éprouvettes axisymétriques entaillées. Elles nous ont permis de déterminer que le critère de Rice et Tracey est bien adapté à la rupture de notre matériau. Nous avons étudié l'influence de la vitesse de sollicitation sur le comportement et la rupture du matériau en réalisant des essais à différentes vitesses, en particulier à l'aide du montage des barres de Hopkinton en compression et en traction. Un meilleur mode de dépouillement des essais dynamiques bases sur des calculs par éléments finis a été mis en place. De plus, l'instrumentation des éprouvettes axisymétriques entaillées a été améliorée. Des informations sur les mécanismes d'endommagement et de rupture ont été obtenues à l'aide de l'essai de traction de mini éprouvette dans l'enceinte d'un microscope électronique à balayage. L’endommagement débute avec la rupture des particules de silicium, il se poursuit par la croissance et par la coalescence de ces cavités. Il se crée des microfissures. L’ensemble de ces microfissures croient jusqu'a la jonction de plusieurs microfissures qui provoque la ruine de la matière. Cette dernière étape n'apparait pas dans le cheminement classique de la rupture ductile. Une technique pour tester les supports moteurs reproduisant au mieux le chargement de cette pièce lors d'un crash test véhicule a été mis au point. Nous avons ensuite modélisé par éléments finis cet essai en utilisant la loi de comportement et le critère de rupture de Rice et Tracey que nous avons déterminé avec les essais sur éprouvettes. Ce critère apporte une amélioration de la prédiction de rupture par rapport au critère de mises jusqu'alors utilise. Nous prédisons avec une bonne précision le comportement ainsi que la rupture (lieu et niveau d'effort) du support moteur.
10
Serveaux, Jérémy. "Rupture ductile d’un conteneur de déchets radioactifs HA soudé et soumis à une corrosion généralisée". Thesis, Troyes, 2019. https://tel.archives-ouvertes.fr/tel-03180078.
Testo completoAbstract (sommario):
L’Agence nationale pour la gestion des déchets radioactifs (Andra) est en charge d’étudier le stockage des déchets de Haute Activité (HA) dans un centre de stockage géologique (projet Cigéo). Il est prévu d’encapsuler les déchets HA dans des conteneurs mécano-soudés en acier non allié P285NH, puis de les insérer dans des alvéoles de stockage réalisées dans une formation argileuse à 500 m de profondeur. L’objectif principal de la thèse est de savoir si le modèle proposé et la méthode numérique associée sont capables de prédire fidèlement le comportement à long terme (plusieurs centaines d’années) de ces conteneurs en situation de stockage, notamment l’épaisseur critique à partir de laquelle la rupture ductile apparait. Le comportement ductile de l’acier P285NH a été caractérisé par des essais sur des éprouvettes prélevées sur une maquette échelle 1:1. Des essais de traction ont été réalisés sur des éprouvettes lisses et entaillées issues du matériau de base ainsi que du joint soudé. Pour ces matériaux, un modèle de comportement élastoplastique avec écrouissages non linéaires cinématique et isotrope fortement couplés à l’endommagement ductile isotrope et faiblement couplé à la corrosion généralisée, a été développé. Sa formulation est basée sur la thermodynamique des processus irréversibles avec des variables d’état macroscopiques en considérant des grandes déformations plastiques. Plusieurs cas de simulations sur conteneurs soumis à différents chargements mécaniques et vitesses de corrosion sont réalisésAndra, the French national radioactive waste management agency, is in charge of studying the possibility of disposal of High Level activity Wastes (HLW) in deep geological repository. Andra has planned to encapsulate HLW in non-alloy P285NH steel overpacks before inserting them into horizontal steel cased micro-tunnels called HLW disposal cells. The objective of this PhD is to study the long-term behavior of a welded steel overpack subjected to mechanical loading and generalized corrosion. Several tensile tests have been performed on smooth and notched specimens taken from both base material and welded material. For these materials, an elastoplastic behavior model with mixed nonlinear hardening strongly coupled with ductile isotropic damage and weakly coupled with generalized corrosion is developed. It is formulated based on the classical thermodynamics of irreversible processes framework with state variables at the macroscopic scale assuming the large plastic strains and small elastic strains. The comparisons between numerical and experimental results allow us to be confident in the capability of numerical simulations performed on P285NH to simulate the initiation and propagation of cracks. Finally, the addition of corrosion allows performing multiple simulations on overpacks, subjected to different mechanical loading conditions and corrosion conditions
Libri sul tema "Simulations de rupture ductile"
1
Mundheri, Mohammed H. Al. Approches globale et locale de la rupture fragile et ductile d'aciers faiblement alliés (16 MND 5) influence de l'irradiation. Grenoble: A.N.R.T, Université Pierre Mendes France (Grenoble II), 1986.
Cerca il testo completoCapitoli di libri sul tema "Simulations de rupture ductile"
1
Miannay, Dominique P. "Microscopic aspect of fracture: Cleavage and ductile rupture". In Mechanical Engineering Series, 102–54. New York, NY: Springer New York, 1998. http://dx.doi.org/10.1007/978-1-4612-1740-4_5.
Testo completo
2
Sandström, Rolf. "Creep Ductility". In Basic Modeling and Theory of Creep of Metallic Materials, 257–73. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-49507-6_13.
Testo completoAbstract (sommario):
AbstractFor a number of creep resistant steels, the creep ductiliy decreases with increasing temperature and time. As a function of stress, the ductiity is often describe with an S-shaped curve with an upper and a lower shelf level. As a function of time, the S-shape is inverted. If the ductility is high, the rupture is referred to as ductile, and for low ductility levels as brittle. Ductile rupture is believed to be due to a plastic instability such as necking. Brittle rupture on the other hand is controlled by the nucleation, growth and linkage of creep cavities. With the help of the basic models for creep deformation and cavitation, the rupture stress and ductility can be predicted. Several models exist for the influence of multiaxiality on the creep ductility. Although the models are based on different principles, they predict approximately the same behavior, which is verified by comparison to rupture data for notched bars.
3
Regenauer-Lieb, K., e D. A. Yuen. "Multiscale Brittle-Ductile Coupling and Genesis of Slow Earthquakes". In Earthquakes: Simulations, Sources and Tsunamis, 523–43. Basel: Birkhäuser Basel, 2008. http://dx.doi.org/10.1007/978-3-7643-8757-0_5.
Testo completo
4
Spielmannová, Alena, Anna Machová e Petr Hora. "Crack Orientation versus Ductile-Brittle Behavior in 3D Atomistic Simulations". In Materials Science Forum, 61–64. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-469-3.61.
Testo completo
5
Dong, Xuelin, e Zhiyin Duan. "Rupture Failure of Tubing and Casing with a Crack in Mixed Modes". In Computational and Experimental Simulations in Engineering, 405–12. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-67090-0_32.
Testo completo
6
Roten, D., K. B. Olsen, S. M. Day e Y. Cui. "Quantification of Fault-Zone Plasticity Effects with Spontaneous Rupture Simulations". In Pageoph Topical Volumes, 45–67. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-72709-7_5.
Testo completo
7
Szuwalski, K. "Bars of Uniform Strength vs. Optimal with Respects to Ductile Creep Rupture Time". In Creep in Structures, 637–43. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-84455-3_73.
Testo completo
8
Brackmann, Lukas, Arne Röttger, Hoang-Giang Bui, Sahir Butt, Golnaz Hoormazdi, Abdiel Ramon Leon Bal, Sebastian Priebe et al. "Excavation Simulations and Cutting Tool Wear". In Interaction Modeling in Mechanized Tunneling, 93–164. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-24066-9_3.
Testo completoAbstract (sommario):
AbstractThe mechanized tunnel construction is carried out by tunnel boring machines, in which the soil in front of the working face is removed, and the tunnel lining is carried out with shotcrete or the setting of segments and their back injection. Advancements in this field aim towards increase of the excavation efficiency and increase of the tool lifetime, especially in rock-dominated grounds. The latter is achieved by understanding the wear mechanisms abrasion and surface-fatigue, and by knowledge of the microstructure-property relation of the utilized materials. Improvements for tool concepts are derived, based on experiments and simulations. A key parameter towards efficient rock excavation is the shape of the cutting edge of the utilized disc cutters. Sharp cutting edges have proven to generate higher rock excavation rates compared to blunt ones. The compressive strength of the utilized steel has to be high, to inhibit plastic deformation and thereby to maintain sharp cutting edges. This requirement competes with the demand for toughness, which is necessary to avoid crack-growth in the case of cyclic loading. Solutions for this contradiction lie in specially designed multiphase microstructures, containing both hard particles and ductile microstructural constituents. Besides adapting the alloying concept, these required microstructures and the associated properties can be adjusted by specific heat-treatments.
9
Harris, Ruth A. "Numerical Simulations of Large Earthquakes: Dynamic Rupture Propagation on Heterogeneous Faults". In Computational Earthquake Science Part II, 2171–81. Basel: Birkhäuser Basel, 2004. http://dx.doi.org/10.1007/978-3-0348-7875-3_5.
Testo completo
10
Brünig, Michael, Steffen Gerke e Daniel Brenner. "Experiments and Numerical Simulations on Stress-State-Dependence of Ductile Damage Criteria". In Inelastic Behavior of Materials and Structures Under Monotonic and Cyclic Loading, 17–33. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-14660-7_2.
Testo completoAtti di convegni sul tema "Simulations de rupture ductile"
1
Remmal, Al Mahdi, Stéphane Marie e Jean-Baptiste Leblond. "New Model for Ductile Rupture Under Cyclic Loading Conditions". In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93836.
Testo completoAbstract (sommario):
Abstract Experiments have shown that ductile failure occurs sooner under cyclic loading conditions than under monotone ones. This reduction of ductility probably arises from an effect called “ratcheting of the porosity” that consists of a continued increase of the mean porosity during each cycle with the number of cycles. Improved micromechanical simulations confirmed this interpretation. The same work also contained a proof that Gurson’s classical model for porous ductile materials does not predict any ratcheting of the porosity. In a recent work [6], the authors proposed a Gurson-type “layer model” better fit than Gurson’s original one for the description of the ductile behavior under cyclic loading conditions, using the theory of sequential limit analysis. A very good agreement was obtained between the model predictions and the results of the micromechanical simulations for a rigid-hardenable material. However, the ratcheting of the porosity is a consequence of both hardening and elasticity, and sequential limit analysis is strictly applicable in the absence of elasticity. In this work, we make a proposal to take into account elasticity in the layer model through the definition of a new objective stress rate leading to an accurate expression of the porosity rate accounting for both elasticity and plasticity. This proposal is assessed through comparison of its predictions with the results of some new micromechanical simulations performed for matrices exhibiting both elasticity and all types of hardening: isotropic, kinematic and mixed, to better comply with the hypothesis made to derive the model.
2
Suga, Kazuhiro, Katsumasa Miyazaki, Ryotaro Senda e Masanori Kikuchi. "Ductile Fracture Simulation of Mulitple Surface Flaws". In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57147.
Testo completoAbstract (sommario):
Effect of surface flaw on ductile fracture behavior of non-aligned multiple flaws in plate is studied numerically using Gurson’s constitutive equation. Based on experiments, 2 parallel crack problems are simulated. In experiments and simulation crack coalescence, crack non coalescence and crack interaction was observed. In all cases, ductile fracture processes are obtained and results are compared with experimental ones. In this study, a new alignment rule for the prediction of maximum tensile load or rupture load for multiple cracked plates is compared with the simulation result.
3
Bonora, Nicola, Domenico Gentile, Andrew Ruggiero, Gabriel Testa, Paolo Folgarait e Andrea Calatroni. "Failure Assessment of Pipe Tee Element Using Continuum Damage Mechanics". In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97344.
Testo completoAbstract (sommario):
In this work continuum damage mechanics was used to try to predict the occurrence of ductile rupture in a barred tee fitting subjected to pressure load. In order to account for the scatter in the material damage parameters, a stochastic definition was used. Ductile damage parameters were identified using failure data obtained from traction tests of round notched bar samples. The attention is concentrated on the possible failure of the grid since it occurrence can obstruct the pipe flow and drive the structural failure of the tee Numerical simulation indicates that the bars fail first but do not trigger the tee rupture. The location where ductile rupture is expected to initiate in the tee was found to be 30° out of the tee symmetry plane.
4
Remmal, Al Mahdi, Stéphane Marie e Jean-Baptiste Leblond. "Experimental Determination of the Ratcheting of the Porosity for the Study of Ductile Rupture Under Cyclic Loading Conditions". In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93831.
Testo completoAbstract (sommario):
Abstract It is known that for ductile porous materials, cyclic loadings lead to lower fracture strains than monotone ones. This reduction of ductility probably arises from an effect called “ratcheting of the porosity” that consists of a continued increase of the mean porosity during each cycle with the number of cycles. Finite element based micromechanical simulations confirmed this interpretation. Recently the authors proposed a Gurson-type “layer model” better fit that Gurson’s original one which does not predict the ratcheting of the porosity, for the description of the ductile behavior under cyclic loading conditions. A very good agreement was obtained between the results of the micromechanical simulations and the model predictions for a rigid-hardenable material. Yet, the ratcheting of the porosity is a consequence of both hardening and elasticity; and the theory of sequential limit analysis used in order to get the “layer model” is strictly applicable in the absence of elasticity. Based on an expression of the porosity rate accounting for elasticity, a proposal was made to improve the new model with regard to elasticity. Simultaneously to this theoretical work, an experimental program was conducted on a model material in order to assess experimentally this new model. The material is a HIPed 316L stainless steel, with Al2O3 almost spherical inclusions acting like porosities, complying with the hypothesis made to derive the theoretical model. Notched tensile specimens, with a center section of 4mm, were cyclically loaded. Several tomographies were performed at ESRF, using a 120 keV beamline and 3x3 microns detector, in order to prove experimentally the ratcheting effect of the porosity. The void growth through the cycles is precisely described and the experimental results could then be processed and compared to the numerical porosities predictions of the model. This paper presents the experimental activity of this PhD program.
5
Reytier, M., S. Chapuliot e M. Ne´de´lec. "Tests and Calculations of Thermomechanical Shocks in the Brittle/Ductile Transition Zone of a Pressure Vessel Steel". In ASME 2003 Pressure Vessels and Piping Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/pvp2003-1996.
Testo completoAbstract (sommario):
In order to study the effects of a sudden cooling in a thick hot structure, such as the vessel of a pressurised water reactor, a specially-adapted compact tension specimen has been developed. It consists of a CT50 (2T-CT specimen) with holes through the specimen to cool the crack tip locally by liquid nitrogen. Therefore, this new test allows to study in details different loading-temperature histories near the brittle/ductile transition zone which may put the classical crack intiation criteria in the wrong. First, this article describes in details two tests for which a cleavage rupture has been obtained during the thermal shock on this 16MND5 steel. Either the Crack Mouth Opening Displacement was maintained during the test or the applied load. Then, numerical calculations have been realised in order to estimate the local mechanical fields at the crack tip and to evaluate the global fracture mechanics parameters. Thanks to these tests and these thermal and mechanical simulations, a work is done on rupture criteria under thermal shocks by using either the “Master Curve” approach or the Beremin model.
6
Mohajer Rahbari, Nima, J. J. Roger Cheng e Samer Adeeb. "On the Critical Boundary Conditions for Rupture of Buckled Steel Pipelines". In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65763.
Testo completoAbstract (sommario):
The environmental contamination due to the leakage of energy pipelines is a serious hazard to the public property and safety. Hence, any premature rupture should be dealt with in the design and the operating mode of steel pipes. A large amount of complexity is involved in the soil-pipe interactions that makes it so challenging to discover the physical boundary conditions (BC) applied to the buried pipelines during differential ground movements. Therefore, the most critical boundary conditions of buried pipes should be conceived based on the probable mechanism of soil-pipe interactions and considered in the experimental and analytical simulations of rupture. The focus of the current research is to address the critical boundary conditions that can trigger the rupture of underground wrinkled pipelines whilst being subjected to a monotonic increase of curvature. Finite element (FE) simulation of a full-scale bending test on a pressurized X70 line pipe specimen conducted at the University of Alberta is implemented. Cumulative fracture criterion coupled with the equivalent plastic strain to fracture for X70 steel grade is fed into the analysis to predict the ductile crack formation in the pipe’s body. The FE model is verified by the experimental data and is used to study the critical soil-pipe interactions that provoke the rupture of buckled steel pipes on the tensile side of the cross-section under increasing bending curvature. The results of this study suggest that the pipelines which are restricted from axial displacements are extremely vulnerable to experience a rupture along their post-buckling loading path. And so are the pipelines in which tensile axial force is developed due to soil-pipe interactions, e.g. pipelines in arctic regions that are installed during the summer time.
7
Jaquay, Kenneth R., e Michael J. Anderson. "Yucca Mountain Project Structural Fragility Estimates for Impact Loading of Waste Packages". In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-66538.
Testo completoAbstract (sommario):
A methodology is presented for estimating the ultimate structural capability (fragility) of metallic nuclear waste disposal containers (waste packages) subject to impact events. The LS-DYNA finite element analysis (FEA) computer code and massively parallel processing (MPP) is used for nonlinear, dynamic-plastic, large-distortion impact simulations. The fragility estimate for risk assessments uses strain energy concepts, a ductile-rupture damage criterion and tri-linear stress-strain curves adjusted for material cold-forming triaxiality and weldment toughness scatter. FEA examples are provided for waste package impacts on ground support structures.
8
Margolin, B. Z., V. I. Kostylev, E. Keim e R. Chaouadi. "Local Approach of Fracture in the Ductile Regime and Application to VVER Materials". In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22710.
Testo completoAbstract (sommario):
Within the TACIS R2.06/96 project: “Surveillance Program for VVER 1000 Reactors”, sponsored by the European Commission, the local approach of fracture has been applied in the ductile regime. Two different models were applied and compared, namely Tvergaard-Needleman-Gurson versus Prometey model. The main tasks are: • perform special Local Approach experiments on smooth and notched cylindrical specimens; • predict JR-curve on the basis of the ductile fracture models; • compare two models of ductile fracture, namely, the Tvergaard-Needleman-Gurson model and the Prometey model. In this paper, the Tvergaard-Needleman-Gurson and Prometey models are briefly described. The parameters of both models were calibrated by using experimental data obtained on tensile specimens. While only smooth tensile specimens are used to calibrate the Tvergaard-Needleman-Gurson model, notched tensile in addition to smooth tensile specimens are used to calibrate the Prometey model. In the latter, standard smooth tensile specimens are used to determine the mechanical properties (the yield stress σy, the ultimate stress σu, the ultimate elongation δu, the area reduction Z) and notched cylindrical specimens to determine the strain at rupture. The numerical analysis comprises essentially two steps: • Step 1: finite element simulation of the smooth tensile specimen (determination of true stress-strain curve and critical void volume fraction for the Tvergaard-Needleman-Gurson model) and simulation of the notched cylindrical specimen up to rupture (determination of stress triaxiality for the Prometey model); • Step 2: finite element simulation of the 2T CT specimen and determination of the crack resistance behaviour in the ductile regime (J-Δa curve). It is found that both models were able to correctly predict the crack resistance behaviour of the investigated materials. The numerical and the experimental results were in very good agreement. The main difference between the two models is that the required number of calibrated parameters in the Prometey model is less than in the Tvergaard-Needleman-Gurson model but additional tests on notched specimens are required for the Prometey model.
9
Igi, Satoshi, Mitsuru Ohata, Takahiro Sakimoto, Junji Shimamura e Kenji Oi. "Buckling and Tensile Strain Capacity of Girth Welded 48″ X80 Pipeline". In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10994.
Testo completoAbstract (sommario):
This paper presents the experimental and analytical results focused on the compressive and tensile strain capacity of X80 linepipe. A full-scale bending test of girth welded 48″ OD X80 linepipes was conducted to investigate the compressive strain limit regarding to the local buckling and tensile strain limit regarding to the girth weld fracture. As for the compressive buckling behavior, one large developing wrinkle and some small wrinkles on the pipe surface were captured relatively well from observation and strain distribution measurement after pipe reaches its endurable maximum bending moment. The tensile strain limit is discussed from the viewpoint of competition of two fracture phenomena: ductile crack initiation / propagation from an artificial notch at the HAZ of the girth weld, and strain concentration and necking / rupture in the base material. The ductile crack growth behavior from the girth weld notch is simulated by FE-analysis based on the proposed damage model, and compared with the experimental results. In this report, it is also demonstrated that the simulation model can be applicable to predicting ductile crack growth behaviors from a circumferentially notched girth welded pipe with internal high pressure subjected to post-buckling loading.
10
Di Biagio, M., G. Demofonti, G. Mannucci, F. Iob, C. M. Spinelli e T. Schmidt. "Development of a Reliable Model for Evaluating the Ductile Fracture Propagation Resistance for High Grade Steel Pipelines". In 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90614.
Testo completoAbstract (sommario):
The recent experience on ductile fracture propagation control on gas pipelines has shown that the applicability of the Battelle Two Curve Method (based on Charpy-V energy) to high grade steel pipes from API5L-X80 to X120 (ISO3183-L555M to L830M) operated at very high hoop stress values (≥500 MPa) is highly questionable. The reduced geometry of the specimen, the intrinsic low value of ductility of very high strength steels, as low work-hardening and low value of the strain at maximum load are pointed out as the main causes of the mismatch. Starting from these assumptions a new EPRG (European Pipeline Research Group) project has been launched with the aim to develop, with reference to the ductile fracture propagation resistance, a suitable fracture parameter(s) with an associated laboratory methodology based on a simple sample which would be able to take into account the role of the ductility of the material on this specific fracture event. The present paper shows the approach adopted in this EPRG Project: an innovative approach based on “plastic damage model” which allows to describe the stable ductile crack propagation by means of stress-state parameters (named triaxiality and deviatoric parameters). Moreover the proposed “damage model” has been implemented inside a commercial finite element code and used to predict the fracture crack propagation behaviour of Single Edge Notch Bend (SENB) tests in terms of load-displacement diagram and residual plastic deformation. One of the main topics of this project was the application of this method to six selected grade steels (with grades in the range of API X65 – X100) many of them coming from experimental full scale burst tests. The comparisons between experimental results and numerical simulations are substantially good; besides the results confirm that Charpy-V specimens, during the fracture propagation, work in different “constraint” conditions with respect to pipe and that DWTT specimen is in the middle between the two. Finally the “damage model approach” seems also able to discriminate between low and high grade steels in terms of failure deformation at rupture. So it resulted very promising to quantify the role of both ductile of the steel and geometrical constraint of the specimen in the ductile fracture propagation event.
Rapporti di organizzazioni sul tema "Simulations de rupture ductile"
1
Boyce, Brad L., Jay D. Carroll, Phillip Noell, Daniel Charles Bufford, Blythe G. Clark, Khalid Mikhiel Hattar, Hojun Lim e Corbett C. Battaile. Mechanisms for Ductile Rupture - FY16 ESC Progress Report. Office of Scientific and Technical Information (OSTI), gennaio 2017. http://dx.doi.org/10.2172/1340630.
Testo completo
2
Luh, M. H., e J. S. Strenkowski. Simulations of ductile flow in brittle material processing. Office of Scientific and Technical Information (OSTI), dicembre 1988. http://dx.doi.org/10.2172/476646.
Testo completo
3
Pitarka, Arben. Rupture Dynamics Simulations for Shallow Crustal Earthquakes. Office of Scientific and Technical Information (OSTI), febbraio 2019. http://dx.doi.org/10.2172/1499970.
Testo completo
4
Pitarka, A. Dynamic Rupture Simulations of the Mw7.2 1992 Landers,California, Earthquake. Office of Scientific and Technical Information (OSTI), febbraio 2023. http://dx.doi.org/10.2172/2005094.
Testo completo
5
King, W. E., G. H. Campbell, D. L. Haupt, J. H. Kinney, R. A. Riddle e W. L. Wien. Mechanism of ductile rupture in the Al/sapphire system elucidated using x-ray tomographic microscopy. Office of Scientific and Technical Information (OSTI), dicembre 1995. http://dx.doi.org/10.2172/231570.
Testo completo
6
Pitarka, A. Rupture Dynamics Simulations of Shallow Crustal Earthquakes on Reverse Slip Faults. Office of Scientific and Technical Information (OSTI), febbraio 2020. http://dx.doi.org/10.2172/1599564.
Testo completo
7
Kalan, Robert. Development of a Ductile Rupture Failure Surface for PH13-8Mo H950 Steel Using the Xue-Wierzbicki Failure Model. Office of Scientific and Technical Information (OSTI), settembre 2021. http://dx.doi.org/10.2172/1854725.
Testo completo
8
Henshall, G. A., M. J. Strum, P. R. Subramanian e M. G. Mendiratta. Simulations of creep in ductile-phase toughened Nb{sub 5}Si{sub 3}/Nb in-situ composites. Office of Scientific and Technical Information (OSTI), novembre 1994. http://dx.doi.org/10.2172/161524.
Testo completo
9
Phillips e Robinson. L51979 Gas Decompression Behavior Following the Rupture of High Pressure Pipelines-Phase 1. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), novembre 2002. http://dx.doi.org/10.55274/r0010194.
Testo completoAbstract (sommario):
The ability to predict the behavior of a crack propagating in a steel natural gas transmission pipeline is of great importance. This is because a long-running fracture is costly, both in terms of the time taken for replacement, and associated lost revenue, and the cost of replacement of the pipe itself. The determination of ductile shear fracture arrest toughness levels requires an accurate knowledge of the gas decompression behavior following the rupture. In particular, there is a need to predict accurately the gas decompression wave velocity within the pipe as a function of initial pressure, temperature and gas composition. Although models developed in the 1970's have proved remarkably robust to date, even when stretched considerably beyond their range of validation, operational characteristics currently being considered range far beyond any that have been investigated on a realistic scale. There is, therefore, a need to produce a model that has been validated for conditions relevant to next generation pipeline projects. This report describes the work carried out in Phase 1 of a project to produce such a model. In Phase 1 a review of current knowledge was carried out and the work required in Phase 2 of the project was specified. This report describes Phase 1 of the gas decompression project. The aim of Phase 1 was to review the current state of knowledge on pipeline decompression. Carrying out this work has enabled the requirements for the model, the extent of validation that will be required and the proposed technical approach to be identified.
10
Kanninen, M. F. L51718 Development and Validation of a Ductile Fracture Analysis Model. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), maggio 1994. http://dx.doi.org/10.55274/r0010321.
Testo completoAbstract (sommario):
In close cooperation with the Centro Sviluppo Materiali (CSM) and SNAM of Italy, with several years of support from the PRCI NG-18 committee, the Southwest Research Institute (SwRI) has developed and validated a "first principles" predictive model for ductile fracture in a gas transmission pipeline. In particular, the coordinated SwRI and CSM projects for the PRC -supplemented by work contributed by SNAM - has established a theoretically valid methodology and an accompanying line pipe material characterization procedure for gas industry use. This progress provides a theoretically sound framework for designing and operating gas transmission pipelines to be without risk of a large-scale ductile fracture event. However, there remained two important aspects of this technology that needed to be addressed before practical use of the methodology could be made by gas transmission companies. First, because the preceding projects concentrated on pipes with natural gas, to cover the full range of gas transmission pipeline service, the approach needed to be extended to include the effects of gases rich in hydrocarbons. Second, as the number of full-scale pipe fracture experiments that were included in the developmental phase of the research were limited, other data for validation of the model needed to be identified and employed. These two aspects of the ductile fracture methodology development process were conducted concurrently, and have now been completed. The progress that has been provided in detail in this report. The work is culminated by a relation through which the methodology can be applied by pipeline engineers to assess the possibility of a ductile fracture propagation. This report describes the development of a predictive model for ductile fracture in a gas transmission pipeline, thus providing a theoretically sound framework for designing and operating gas pipelines to be without risk of a large-scale ductile fracture event. The model represents an improvement on a number of empirical relations used in designing natural gas pipelines in that this model has been generalized to consider a wide-range of hydrocarbon contents and validated through both additional full-scale instrumented tests carried out by Centro Sviluppo Materiali of Italy and computer simulations conducted at Southwest Research Institute. Application of the model in pipeline design is based on determination of the maximum driving force for fracture, as described in the report, and contrasting this value with measured material resistance that provides a basis for assessing the likelihood of ductile fracture occurring. For existing pipelines the procedure can be used to obtain the maximum operating line pressure that will not put the pipeline at risk of ductile fracture.