MECHANICAL CHARACTERISATION OF A BIO-BASED COMPOSITE PANEL

The increasing demand for environmentally friendly materials and the desire to reduce the cost of traditional fibre, has led to the development of new bio-based composite panels using natural fibres. These fibres offer specific benefits such as low density, low pollutant emissions, biodegradability, high specific properties and low cost. Nevertheless, the mechanical properties of these panels have a large variability, which depends on the manufacturing process, the quality of the fibres and the humidity level, among others. Thus, their properties must be evaluated experimentally by tensile tests or by inverse modelling methods. This article presents an investigation on the mechanical properties of a composite panel made of unidirectional flax fibres embedded in a polyethylene matrix (flax-PE). An initial set of mechanical properties has been carried out by classical static tests. Then, an experimental modal analysis was performed in order to get information on natural frequencies and mode shapes, which are related to the mechanical properties. The experimental results were compared with numerical ones, obtained by means of a finite element model in which the mechanical properties carried out by static test were used. Finally, in order to get a good numerical-experimental correlation, the mechanical properties used in the FE model were updated using an inverse modelling method based on parallel genetic algorithms. Special consideration is taken on the variation of the mechanical properties throughout the panel due to manufacturing or the variability of flax fibres.