Manufacturing of Doubly Curved Tubular Composite Structures: Mapping and Weave Modifications

The versatility of the textile weaving process has made it a popular method for producing structural composite preforms. Enhanced through-thickness strength by multi-layer weaving, good in-plane strength and the ability to produce 2.5D or 3D shapes, are some of the advantages which have made weaving the most commonly used textile process for composite applications. It is also possible to incorporate local modifications to the weave patterns and fibre-densities within the woven structure; although this characteristic of weaving has not been completely exploited by the composites industry. It is easy to produce a tubular structure having good bi-directional mechanical properties. Moreover, the preform also can be molded into bent shapes, making the woven composites more versatile than ever before. Drape behavior of such tubular fabrics is complex and has not previously been investigated. The aim of this paper is to discuss the manufacturing aspects of such tubular preforms and to suggest ways to overcome the wrinkling problems using the mapping results. In terms of the mapping models, existing shear-based algorithms for mapping a flat fabric over open surfaces are first applied to a closed tubular section. Specific algorithms are developed to map a straight tubular preform over a bent tubular section. Wrinkles are prevalent in sections with severe bends and the paper also discusses methods to remove them.