Design of Non-Metallic Tube and Coupling Systems

The results of a design -study to develop a non-metallic duct and coupling system are presented. The objective of the work was to create a duct system which could be used to replace thin-wall aluminum tubing systems used in current aircraft designs. The mechanical, thermal, chemical, and electrical design parameters are given. These parameters were then used to select five design approaches for the duct system: PTFE hose, long-fiber reinforced elastomeric hose, liquid crystalline polymer tube, long-fiber reinforced thermosetting resin tube, and cross-linked long-fiber reinforced thermoplastic tube. The constraints of each design were reviewed in detail indicating long-fiber reinforced thermoplastics as the most promising approach. A thin-walled tube was developed exhibiting several unique properties. Design of the end fittings was shown to be dependent on tubing design and construction. A trade-off study of alternatives yielded a final design complementing the tubing properties and showing unique installation and reliability advantages.