This paper reports results on the shielding effectiveness parameter of laminated epoxy composites with carbon fibre reinforcements. Measurements of shielding effectiveness were carried out with a coaxial transmission line testing chamber according to ASTM 4935 standard and epoxy-matrix composites with continuous carbon-fibres were proven to be an excellent electromagnetic interference shielding material, where a composite slab made of 4 layers of prepregs provided more than 99.9% of electromagnetic attenuation. It was found that the reflection mechanism of the shielding material was mainly influenced by the fibre volume ratio, and that an increase in the number of layers of the composite resulted in higher shielding effectiveness due to a greater absorption mechanism. Calculations of the shielding effectiveness parameter of the material used were made by means of commercial electromagnetic simulation tools, having determined experimentally the overall resistivity of the composite. The findings presented in this work suggest that in presence of a greater number of interfaces at different impedance the separate modelling of matrix and fibres at mesoscopic scale must be taken into account.

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Predictive calculations of the physical properties of fibrous preforms and composite parts require an appropriate description of the preform geometry. Most internal dimensions of a preform are set during its manufacturing through mechanical interactions occurring between the tows and threads. However, the global shape and the interlacing patterns of the constituent textiles are determined independently. In this paper, a formal procedure for the description of the interlacing patterns is proposed. This procedure, which is based on the individual textile manufacturing processes, is general in the textiles considered and in the possible applications. The interlacing patterns are expressed by a series of vectors that follow a universal set of criteria and are generated from the values taken by the processing parameters. Defining examples are given for three-dimensional woven textiles and three-dimensional tubular braided textiles, and geometrical applications are also presented. Further examples for warp-knitted textiles and multiple-layer stacks will be given in a subsequent paper, together with examples of physical applications.

This study analyses the influence of the random filament arrangement in fibre bundles on the resin flow behaviour. Transverse steady-state resin flow that occurs behind a liquid resin flow front was simulated numerically through statistically equivalent micro-structures at high-fibre volume fractions, V f > 0.6, as observed in fibre bundles. The need of applying a minimum gap distance between neighbouring filaments was overcome by automated local mesh refinement. The derived permeability values showed significant scatter. Convergence of these values was determined at a ratio of flow length to filament radius greater than 20 for all three analysed fibre volume fractions. Mean permeabilities were between 6 and 10 times lower than those predicted for a hexagonal fibre array. A statistical model is proposed, which is able to predict the scatter of observed permeabilities based on simple micro-structural descriptors.