Analysis of the behaviour of flax fibre’s biocomposites under static and dynamic loads

Abstract

Composite materials are not new, they have been leading the way in the construction of technologically cutting- edge structures for several decades, specially in the field of aeronautics. In the last few years their use has, however, jumped to some other sectors. The main reason for this popularisation for "earthlier" applications, has been the deepening in their knowledge, specially regarding their manufacturing and maintenance processes, what has caused without any doubt a cheapening in their use. On the other hand, in the last two decades it has arisen across all industries, fields, sectors and social layers of population a raising awareness of care taking of the planet, what has caused an important ecological wave, as resources are limited and the human being is consuming them at an accelerated rate. As a consequence of this deeper knowledge in composites and following this ecological upward tendency, bio composite materials appeared in the 90’s. Among these bio composites the flax fibre is gaining an important role due to its characteristics, which keep a good balance between weight/density and mechanical properties. VESO- Concept is a company settled in Toulouse whose aim is to develop complete organic elements made up with bio composite materials. This thesis fits within the BOPA project, a project between VESO- Concept and ISAE- SUPAERO, the Institut superieur de l’aeronatique et de l’espace. Final objective of this project is the characterization of the behaviour of plies made of flax fibre, specially regarding damage. Models of damage will be developed following others authors theories and they will be put to test taking advantage of the powerful tools that represent the currently finite elements programs. To compare results, real experiments will be carried out. At the same time these experiments will be replicated with FEM program. Experiments will put the bio composite elements under static loads (three point bending test and fracture test) and dynamic loads, through an impact test. Results comparison will help to analyse the validity of the models and improve them.