Search results for "Éléments"

Original strain energy density functions for modeling of anisotropic soft biological tissue

2017

This thesis has focused on the construction of strain energy densities for describing the non-linear behavior of anisotropic materials such as biological soft tissues (ligaments, tendons, arterial walls, etc.) or fiber-reinforced rubbers. The densities we have proposed have been developed with the mathematical theory of invariant polynomials, particularly the Noether theorem and the Reynolds operator. Our work involved two types of anisotropic materials, the first with a single fiber family and the second with a four-fiber family. The concept of polyconvexity has also been studied because it is well known that it plays an important role for ensuring the existence of solutions. In the case o…

Te-As-Se glass microstructured optical fiber for the middle infrared

2009

International audience; We present the first fabrication, to the best of our knowledge, of chalcogenide microstructured optical fibers in Te-As-Se glass, their optical characterization, and numerical simulations in the middle infrared. In a first fiber, numerical simulations exhibit a single-mode behavior at 3.39 and 9.3 μm, in good agreement with experimental near-field captures at 9.3 μm. The second fiber is not monomode between 3.39 and 9.3 μm, but the fundamental losses are 9 dB/m at 3:39 μm and 6 dB/m at 9.3 μm. The experimental mode field diameters are compared to the theoretical ones with a good accordance.

Contribution to the investigation of dynamic responses of human tissues under high velocity impacts using finite element modeling

2022

Thoracic injuries happen frequently in various frameworks of high velocity impact biomechanics. Rib fractures and lung injuries are the most common hard and soft tissue injuries in human thorax. This thesis aims to contribute to the investigation of dynamic responses of human tissues especially ribs and soft tissues under high velocity impacts using finite element modeling. Firstly, a novel strain-rate-dependent elasto-hydrodynamic constitutive law of the synthetic polymer Styrene-Ethylene-Butylene-Styrene (SEBS) gel was proposed and implemented as a user material subroutine in Radioss (Altair Hyperworks) to interpret dynamic behaviors of SEBS gel under various loading configurations. Numer…

Prédiction de la contrainte de rupture de composites unidirectionnels et suivi de l'accumulation de ruptures de fibres

2005

Modeling and numerical simulation of the propagation of pitting corrosion of iron in chlorinated medium : contribution to the evaluation of the durab…

2012

This study deals with the understanding of the mechanisms of pitting corrosion susceptible to occur on carbon steel selected for high level nuclear waste containers. Transport/reaction models have been developed in order to simulate, by finite element method, the propagation of a pit on iron in chlorinated medium. For conservative models, pit is activated by imposing a potential on metal. Thanks to different parametric studies (geometry, environment…) simulations have permitted to classify, by severity order, the factors responsible of the increase or the inhibition of the localized corrosion rate. Otherwise, experiments on occluded (called « lead-in-pencil ») electrodes confirm that confin…

Le pur, l'impur et l'imaginaire des éléments chez Bachelard

2011

International audience

Interconnecteurs métalliques de piles à combustible de type SOFC - Résistance à la corrosion et conductivité électrique à haute température

2009

The need of interconnect to connect individual cells into electrical series in a SOFC stack appears as one of the most important point in fuel cell technology. The main important criteria requires for interconnect is an excellent oxidation resistance in air and in H2/H2O. The goal of this study is to determine the influence on corrosion behaviour of a reactive element oxide coating (La2O3, Y2O3) realized by MOCVD on different metallic alloys like Crofer22APU, Haynes230 and Fe30Cr. The realisation of long ageing (7 700 and 15 400 hours) proved to be insightful. The corrosion kinetic experiments, the oxide scale characterisation and ASR measurements established that the presence of perovskite…

Modélisation de phénomènes locaux : vers leur prise en compte dans la simulation de la cinétique d'oxydation d'un métal.

2006

The oxidation of metals is a complex process involving several mechanisms that take place at different length scale (macroscopic and microscopic). In this work, we try to integrate local phenomena (microscopic scale) in macroscopic models, especially to the modelling of the metal oxidation kinetics. The study is divided in two parts ; the first one based on non-equilibrium thermodynamics allows us to obtain the evolution laws of the system metal/oxyde, those were used to modelling oxidation kinetics. The second one is microscopic ; it consists in a study of the thermo-mechanical behaviour of various aluminium surfaces by molecular dynamic and the calculation of their surface energy density.…

En direct de l’essai patrimonial des 42 parcelles d’INRAE à Versailles : impacts de fertilisations centenaires en profondeur du NEOLUVISOL de lœss

2020

International audience; Après l’étude d’évolutions pédologiques et géochimiques dans l’horizon de surface (van Oort et al., 2016, 2017a), ce nouveau volet du projet de valorisation du dispositif des 42 parcelles de l’Inra de Versailles présente les effets d’apports continus de matières fertilisantes à l’échelle du solum, pour une dizaine de traitements : ammoniacaux, engrais-Na et/ou K, phosphatés, CaCO$_3$, fumier et témoins. Pour chaque traitement, les profils de teneur en éléments (0-120 cm) ont été comparés avec le bilan 1929-2014 en surface (0-25 cm), afin de raisonner la pertinence d’études des impacts d’activités anthropiques, restreintes à l’horizon de surface. En l’absence de végét…

Entre air et terre: les éléments dans Aurora Leigh d'Elizabeth Barrett Browning

2010

Surprinsingly enough, despite the fact that it is strongly associated with femininity, Elizabeth Barrett Browning has no use for water as an element in her narrative of Aurora Leigh's progress as a poet in the eponymous poem. Fire is only used in its usual purifying function. But she does construct a complex architecture from the elements of aire and earth. She starts with the generally accepted duality of earth, both nurturing and a symbol of death. She multiplies the associations with air: angels and squirrels, wind and mountains, to cite only a few. She then examines and redefines the relationships between these two elements in liofe and in poetry and finally reaches a mystical union anc…