On high velocity impact on carbon fibre reinforced polymers

The gaining popularity of composites and their typical applications (e.g. aerospace, energy and defence) are driving the requirements for the dynamic characterisation of these materials. Carbon fibre reinforced polymers (CFRP), which are the main concern in this work, are composed of stiff, brittle fibres encased in epoxy resin. Their microstructure results in pronounced anisotropy which makes their characterisation challenging even in basic quasi-static mechanical tests. It must be pointed out that the anisotropy and heterogeneity lead to a complexity in behaviour of these materials including a number of failure mechanisms in the material that are activated by different loading conditions. Despite extensive research in the last three decades, a widely accepted and reliable failure theory for composites does not exist [1][2]. The work in progress, presented here, is related to development of the damage part of a constitutive model intended for modelling of high velocity impact on CFRP aerospace structures. The model is based on spectral decomposition of the material stiffness tensor and strain energy. The model development was supported by extensive mesoscale modelling of the effects of physical damage on the damage parameters related to the material deformation eigenmodes. This is done as part of an integrated effort to produce tools for modelling of high velocity impact on composites in the European project EXTREME∗∗.