Les matériaux cellulaires fragiles

Les matériaux cellulaires fragiles suscitent aujourd'hui un intérêt croissant dans différents domaines d'applications. Ces mousses allient faible densité et bonnes performances mécaniques ce qui les compatible avec une utilisation comme matériaux d'allègement des structures ou d'absorption d'énergie. L'objectif de la présente étude est double.Il consiste à caractériser le comportement mécanique d'une mousse à matrice vitreuse utilisée comme absorbeur de choc et à identifier un modèle de comportement macroscopique en vue de prédire la réponse mécanique du matériau sous des sollicitations complexes. Dans ce but, des essais de compression libre et confiné à différentes vitesses de déformations ont été effectués sur des éprouvettes cylindriques. La réponse multiaxiale a été caractérisée à travers des essais triaxiaux sur la machine Astrée du LMT-Cachan. Les mécanismes d'endommagement mis en jeu lors des essais de compression quasi-statique ont été observés et analysés via la micro-tomographie RX. A partir des résultats expérimentaux, le modèle de Deshpande Fleck légèrement modifié a été identifié. La capacité du modèle à décrire des modes de sollicitation complexes a été validée à partir d'essais d'écrasement des minus – capots métallique remplie de la mousse céramique.

Résultats (Anglais) 1:

Fragile cellular materials today interest growing in various areas of applications. These foams combine low density and good mechanical performance which compatible with use as relief structures or energy absorption materials. The objective of this study is twofold. It is to characterize the mechanical behavior of a mousse glassy matrix used as a shock absorber and identify a macroscopic constitutive model for predicting the mechanical response of the material under complex stress. For this purpose, compression tests free and confined at different rates of deformation are made on cylindrical specimens. The multiaxial response has been characterized through Triaxial tests on the Astrée of LMT-Cachan machine. Mechanisms of damage put at stake during quasi-static compression tests have been observed and analyzed via the RX tomography. From the experimental results, the slightly modified Deshpande Fleck model has been identified. The ability of the model to describe complex patterns of solicitation was posted from the UNMIS crushing tests - ceramic foam-filled metal hoods.

Résultats (Anglais) 2:

Fragile cellular materials today there is growing interest in different fields of applications. These foams combine low density and good mechanical performance that's consistent with use as relief structures or energy absorbing materials. The objective of this study is double.Il is to characterize the mechanical behavior of a foam glass matrix used as a shock absorber and identify macroscopic behavior model to predict the mechanical response of the material under complex loading . For this purpose, the free compression tests and confined at different strain rates were performed on cylindrical specimens. The multiaxial response was characterized through triaxial tests on Astree machine LMT-Cachan. The damage mechanisms involved during quasi-static compression tests were observed and analyzed using the micro-tomography RX. From the experimental results, the model slightly modified Deshpande Fleck has been identified. The model's ability to describe complex stress modes has been validated from crushing tests of minus - metal covers filled with ceramic foam.

Résultats (Anglais) 3:

The cellular materials fragile today, there is a growing interest in various fields of applications. These foams combine low density and good mechanical performance which the compatible with use as a materials of alleviation of structures or absorption of energy. The objective of this study is twofold.It is to characterize the mechanical behavior of a foam matrix to vitreous used as shock absorber and to identify a model of macroscopic behavior in order to predict the mechanical response of the material under the stresses complex. For this purpose,The tests of compression free and confined to different speeds of deformations have been carried out on cylindrical specimens. The answer robot has been characterized through of triaxial testing on the machine Astree of the LMT-Cachan. The mechanisms of damage put into play during the tests of compression quasi-static have been observed and analyzed via the micro-computed tomography X-RAY.From the experimental results, the model of Deshpande Fleck slightly modified has been identified. The ability of the model to describe the modes of solicitation complex has been validated from crushing tests of UNMIS - metal hoods filled the ceramic foam.