Current definition of the microstructure of fibre-reinforced composite
materials is usually limited to the definition of the materials used
and the proportion and orientation of the fibres. Significant differen
ces can be achieved within such a definition, particularly in respect
of the spatial distribution of fibres within the material. The microst
ructure-mechanics relationship is gaining importance as the discipline
of mesomechanics. Recent advances in computer hardware, and in softwa
re for image processing and analysis, have permitted the rapid definit
ion of spatial microstructural parameters. This paper reviews the prep
aration of samples for optical microscopy and the use of image analysi
s for the definition of microstructure in fibre-reinforced composites.