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

Investigating Ramp Wave Propagation inside Silica Glass with Laser Experiments and Molecular Simulations

Under elastic shock compression silica glass exhibits a very specific behaviour. A shock propagating inside a material is usually seen as the propagation of a discontinuity. However in silica glass, shocks are unstable and lead to the propagation of a ramp wave where the shock front becomes gradually larger over time. Ramp waves were already reported in the literature, however their origin remain uncertain. This work presents an original study combining laser shock-induced experiments and molecular dynamics simulation aiming to improve the understanding of the mechanisms involved. Experimental ramp waves were directly observed using shadowgraphy technique allowing for an estimation of the head and tail velocities. Molecular dynamics simulations were carried out in order to reproduce ramp waves and to gain insight into the material properties. Ramp waves were observed for both elastic and plastic shockwaves. In the latter case, the plastic waves were preceded by an elastic ramp precursor. The sound speed, related to the material compressibility, was found to decrease with increasing pressure, as observed experimentally for quasi-static hydrostatic loading, thus providing an explanation for the instabilities that lead to the propagation of ramp waves

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

No abstract provide

Quantitative characterization of the mechanical behaviour of Ceramic Matrix Composites.

No abstract provide

Micro-indentation et densification : influence du coefficient de Poisson et forme des zones affectées; une étude analytique

L'influence du coefficient de Poisson sur la susceptibilité à la formation de zones de densification, ainsi qu'à leurs formes, lors d'indentations faibles charges est mise en évidence analytiquement. Les modèles utilisés sont ceux de Yoffe dont la pertinence physique de l'étude permet une intégration facile dans un schéma analogue à un schéma de (semi)-inclusion d'Eshelby. Une bonne cohérence est obtenue avec l'expérimental

A study of the micromechanical push-out test: Response of an SCS-6/Ti-6242 composite

Push-out tests have been performed on unidirectional SiCfibre/Ti-6242-matrix composites, with samples of variable thickness and fibre volume fraction. Experimental results show the existence of two distinct decohesion types. SEM observations establish that these two types are characterised by two decohesion sites. Since these mechanisms appear to be linked with geometrical parameters, a finiteelement analysis has been developed. This allows us to evaluate the stress field induced by the material manufacture process, the preparation of the sample and the test itself. Two mechanisms are proposed to explain both types of behaviour

Étude du test micromécanique de push-out.

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