Local Anisotropy and Elastic Properties in a ShortGlass Fibre Reinforced Polymer Composite

In short glass fibre reinforced polymers parts obtained by injection moulding, processing conditions produce complex orientation patterns that influence the mechanical properties of the component. In this work, the problem of whether a morphological description can be predictive of the elastic behaviour of these materials is addressed, with particular reference to the shell and core zones identified in a PA6-GF 30 sample. Morphological parameters considered include fibre volume fraction, Mean Intercept Length (MIL) fabric tensor eigenvalues and principal directions. Apparent elastic moduli values in different sites within the sample were computed by simulations using a numerical model based on the Cell Method. Both morphological and numerical methods were able to capture the principal directions of anisotropy and the differences between shell and core and among the volumes of interest within each region. Even if the fabric tensor, normalised, eigenvalues did not show a significant correlation to the apparent elastic moduli, approximately 92% of stiffness components variance could be accounted for by changes in MIL eigenvalues once normalised values were used for elastic moduli as well.