A quantitative mesoscale characterization of the mechanical behaviour of Ceramic Matrix Composites

An experimental micro-macro kinematic description of matrix cracking in unidirectionnal ceramic matrix composites is proposed. It has been enlighten by observations performed during an in situ tensile test in a Scanning Electron Microscope. The characterization of matrix crack nucleation, propagation and coalescence has been done with new parameters and related to the macroscopic behaviour

Multiscale approach of mechanical behaviour of SiC/SiC composites: Elastic behaviour at the scale of the tow

SiC/SiC composites are candidates for structural applications at elevated temperatures in the context of the development of the 4th generation of nuclear reactors. A multiscale approach is under development to construct a predictive modelling of their complex mechanical behaviour due to their heterogeneous microstructure. This approach is based on two scale transitions: from the fibres/matrix microstructure to the tow and from the tow to the woven composite, each scale presenting a significant residual porosity. This paper focuses on the first scale transition and on the modelling of the elastic behaviour of the tow at room temperature. A microstructural investigation of several tows in a 2D SiC/SiC specimen has been conducted using scanning electron microscopy to get statistical data on microstructural characteristics by image analysis in order to generate a virtual microstructure. The elastic problem of homogenisation is numerically solved by means of finite element techniques. The simulations performed on various volumes show noticeable fluctuations of the apparent behaviour: so separation of length scales is not satisfied in this material. Nevertheless, this problem is neglected in a first approximation and the homogeneous equivalent behaviour is evaluated by averaging the apparent behaviours of several volume elements – smaller than the Representative Volume Element (RVE) – called Statistical Volume Elements (SVEs). Finally, influence of porosity and pores’ morphology is quantified

Caractérisation expérimentale du champ local de déformation dans les matériaux hétérogènes par technique de corrélation d'images numériques

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Propriétés mécaniques à basse température du sélénium vitreux

A method for the preparation of bulk samples of selenium is described. The results of a preliminary investigation of the mechanical properties of this material using uniaxial compression tests at low temperature (T < 300 K) are given : the material is viscous. A permanent strain accompanied by an increase in density can be obtained.Cet article présente, d'une part une méthode de préparation d'échantillons massifs de sélénium amorphe et d'autre part une étude préliminaire des propriétés mécaniques de ce matériau en compression uniaxiale à une température inférieure à la température de transition vitreuse. Le comportement est de type visqueux. Il existe une déformation permanente. La déformation augmente la densité du matériau

A mesoscale experimental approach of plasticity and damage.

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Microextensometry by Image Correlation Applied to Micromechanical Studies Using the Scanning Electron Microscopy

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Influence de la répartition spatiale et de la morphologie des grains monophasés gamma et des grains lamellaires biphasés gamma/alpha2 sur me comportement d'un alliage Ti48Al48Cr2Nb2

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Plastic flow and structural morphology of two phase materials

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Etude expérimentale micromécanique de la déformation, de l'endommagement et de la rupture des alliages à base zirconium hydrurés

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Plastic flow and structural morphology of two phase materials

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