Study of cellular materials by X-ray tomography and finite element modelling
Résumé
Cellular materials are gaining use in different applications. The aim of this work is to perform a two-scale study of the microstructure and mechanical properties of different cellular materials, thanks to X-ray tomography. The mesostructure can be described by low resolution images and corresponds to the architecture of the materials: relative density, distribution of solid phase “walls” and macroporosity, etc. Numerous studies have already been performed about the link between these parameters and the mechanical properties. However, the microstructure of the solid “walls” is also of importance. Their microstructural characteristics (presence of a secondary phase or of defects due to the sintering) can have a strong influence on the macroscopic properties. High resolution observations can be done thanks to the so called “local tomography” version of the technique, in which the sample is placed close to the X-ray source. It is then larger than the field of view but reconstructions can still be achieved, although a little bit noisier. High resolution images obtained with local tomography can thus be combined with lower resolution ones. Moreover, in-situ mechanical tests can be done in the tomograph to observe the damage evolution in relation with the microstructure. Consequently, the mechanical behavior of the cellular materials can be explained according to two scales.