Multi-scale and multi-physics investigation of the curing of bio-sourced composite materials – MOCOMBIO-MEMPHYS

The production of bio-sourced epoxy resin and flax fibre composite parts would permit to lower the environmental impact of automotive and aeronautics industries. These parts are however submitted to complex phenomena during processing, including thermal, chemical and hygroscopic strains. These phenomena strongly impact the products’ quality (including its geometry and mechanical performances) through the development of residual stresses. The measurement and prediction of the material behaviour during processing is therefore necessary in order to estimate the initial mechanical state of the part. Accounting for these different phenomena in order to predict the development of residual stresses and strains within these materials has never been investigated until now. To this end, the MOCOMBIO-MEMPHYS project aims to improve the understanding of the behaviour of flax fiber reinforced epoxy resin composites during processing. This latter will be identified thanks to a multi-physics characterization approach, which will investigate the impact of the degree of cure, temperature and moisture content on the mechanical behaviour of the material. This will permit to identify the constitutive laws of the material, which will feed a predictive tool of the development of residual stresses and strains at the plies scale during the processing of composite parts. Results from this tool will be compared to the strains measured on manufactured parts in order to validate the developed model. A multi-scale approach based on a homogenization-relocalization method will also be adopted in order to predict the development of residual stresses at the fibre scale. The outcomes of this project will permit to make recommendations to composite parts manufacturers concerning the processing of bio-sourced composites. This will improve the quality of the process used and lower the amount of defaults in the produced parts, therefore limiting the environmental impact of the concerned industries.