Abstract
A ‘forest’ of vertically aligned carbon nanotubes (CNTs), synthesised by chemical vapour deposition with an iron catalyst on a silicon substrate, is drawn into a horizontally-aligned CNT web. Previous work has shown that the electro-thermal properties of this web may be tuned by altering the individual length of the CNTs and the number of layers. This paper demonstrates, for the first time, that the orientation and multi-directional layering of the web provides further scope for tuning the electrical conductivity and heat distribution of the composite system. An analytical model based on the thermal conduction theory of anisotropic solids is proposed to predict the electrical conductivity of general multi-layered and multi-directional CNT webs.Specimens with different aspect ratios and web orientations were manufactured and their electrical conductivity and resistive heat distribution measured. All of them were shown to exhibit electrical properties and heating distributions which could be predicted or bounded by the analytical model. Consequently, through tuning the CNT web orientation and layup, various heating patterns may be obtained and designed for specific requirements.
Highlights
Carbon fibre reinforced polymer (CFRP) composite is the predominant material used for the primary structure of the latest generation of wide-body passenger aircraft (e.g. 53 wt% on the Airbus A350 XWB and 50 wt% on the Boeing 787 [1]) delivering a 20% weight reduction over comparable previous-generation aircraft and commensurate reductions in fuel consumption
The thickness of 20 layers of carbon nanotubes (CNTs) web in resin is ∼12 μm, which can be neglected compared with the length and width of the specimens, the laminate can be treated as a two-dimensional system
The results show that depending on the aspect ratio of the specimens, the conductivity, as a function of web orientation, is bound by the two theoretical curves for aspect ratios tending towards zero and infinity
Summary
Carbon fibre reinforced polymer (CFRP) composite is the predominant material used for the primary structure of the latest generation of wide-body passenger aircraft (e.g. 53 wt% on the Airbus A350 XWB and 50 wt% on the Boeing 787 [1]) delivering a 20% weight reduction over comparable previous-generation aircraft and commensurate reductions in fuel consumption. With an incessant drive towards greater efficiency, the industry is seeking novel solutions to reducing energy and maintenance requirements of on-board systems. One such system is the conventional ice protection system used on most aircraft for anti-icing. This relies on hot air bleed ducted from the engine compressor stages, adding non-structural weight and maintenance complexity. While the A350 utilises a conventional iceprotection system, the B787 makes use of an electrical system for wing anti-icing, developed by GKN, where the heating element is a metal spray applied between two insulating glass fibre plies [4]. The anti-icing system used on the nacelles of the B787 remains a conventional engine bleed system
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