Optimal design of fibre composite pressure vessels.

Abstract

Fibre composite pressure vessels are replacing conventional metallic vessels because of their higher efficiencies (stored energy/unit weight). In this study, multi-layered fibre composite pressure vessels have been designed using a Direct Search method to simultaneously determine the optimal design parameters of layer thickness and wind angle (based upon maximum vessel efficiency according to an interactive failure theory). It was shown that the ability of the fibre composite pressure vessel to resist the internal pressure without failure increased with increasing total wall thickness, up to a certain limit, after which little or no increase in failure pressure was possible. It was also shown that an improved design of a fibre composite pressure vessel can be accomplished by increasing the number of individual equal thickness layers in the vessel wall. Additional improvement in the design can be obtained by allowing the thickness of each individual layer to vary, especially for thicker vessels. Peak vessel efficiency generally occurred at the same wall thickness, implying the efficiency is mostly affected by the type of fibre/matrix combination selected. A slight improvement in efficiency was noticed by increasing the number of individual layers and allowing their thicknesses to vary. Finally, the manufacturing and testing aspects are described.