Variability in Composite Materials Properties

Composite materials are created as a quite complex architecture which includes a fibre reinforcement structure and matrix material. Many material parameters play a role when composite structures are modelled, e.g. in finite element models. In addition to the properties of the raw fibre and matrix materials which are used, also geometrical parameters have a significant effect on structural characteristics. Fibre reinforcement geometry together with material properties of fibre and matrix determine homogenised material properties.The first part of the paper gives an overview of the most important processes which are used in composites processing industry. The factors which affect variability are also listed, and the effect of variability on material parameters is mentioned as well. The second part of the paper elaborates the identification of geometrical variability of the fibre reinforcement structure which is encountered with one particular type of composite material, namely a twill 2/2 carbon fibre weave with an epoxy matrix.