On the mechanical characterization of a sunflower-based biocomposite using the grid method
This work is part of a project aimed at developing a new biocomposite material that can be used for building thermal insulation purposes. It deals with the mechanical characterization of this material, which is mainly made of sunflower stem chips and of biomatrix derived from chitosan, the latter being used as binder between the chips. Indeed, panels made of this material must exhibit minimum mechanical properties to be able to sustain various mechanical loads such as dead weight or local stress peaks due to mounting on walls. The goal is to investigate experimentally the link between the macroscopic response of the panels and phenomena that occur at the scale of the constituents, namely the bark and pith chips. The grid method, which is one of the full-field measurement systems employed in experimental mechanics to measure displacement and strain fields, is employed because of the very heterogeneous nature of this material. Heterogeneity is due to both the contrast in rigidity between bark and pith and to the presence of voids within the material. Because of the voids and the pith, a specific marking for the specimen surface under investigation has been developed. Compression tests performed on small briquettes made of this material provides useful information on the local response of the constituents. This also helps establishing a link with the global response of the tested briquettes. Typical experimental results will be shown and analysed during the presentation.