Page 57 - 3D Fibre Reinforced Polymer Composites

46 30 Fibre Reinforced Polymer Composites
Table 2.1 Description of advanced textile manufacturing techniques
Textile process Preform style Fibre orientation Productivityketup
Stitching Complex preforms Dependant upon basic fabric High
(general) possible by combining being stitched productivity.
several structures Short setup time
Stitching Additional fibres Complex fibre orientations Moderate
(embroidery) incorporated onto possible, e.g. maximum stress productivity
basic fabric direction Short setup time
3D Weaving Flat fabrics, simple Wide range of through- High productivity
profiles, integral thickness architectures possible Long setup time
stiffened structures & but in-plane fibres generally
integral sandwich limited to 0190 directions
structures (except with advanced looms)
3D Braiding Open & closed profiles 0 degree fibres. Braiding fibres Medium
.
(I, C. L, Z, 0, T,. .) & between 0-80 degrees. 90 productivity
flat fabrics degree fibres possible Long setup time
Knitting (weft Flat fabrics, integral Highly looped fibres in mesh- Medium
and warp) sandwich structures & like structure productivity
very complex Short setup time
preforms
Knitting (non- Flat fabrics Multi-axial in-plane orientation High productivity
crimp) 0/90/+45/-45. Up to 8 layers Long setup time

It should be stated that these textile manufacturing techniques will not be applicable for
all composite components. Design or manufacturing criteria that favour the use of a
particular textiie process for one application may not necessarily be relevant for another.
It is also possible that for some structures it may be necessary to combine a number of
the textile processes in order to obtain a product that satisfies the many, and often
conflicting, requirements of cost, performance, production rate, manufacturing risk, etc
(Broslus and Clarke, I99 1). This intimate connection between the textile manufacturing
process, the required preform design, the cost and the performance of the resultant
component is of particular importance. It has been mentioned in the descriptions of the
various textile processes that there is a very large range of possible preform
architectures that can be produced, each with its own mechanical performance and
associated cost. It is therefore critical that in the design of any component early
consideration is given to the method of manufacture as only slight, relatively
unimportant changes to component shape or required performance may result in
significant changes to the manufacturing process utilised and the cost of final preform.
In spite of the relative youth of these manufacturing techniques, advanced textile
preforms are beginning to be used in the manufacture of composite components
(Hranac, 2001). The potential savings in cost and improvements in performance that
can be realised through the use of these processes are sufficiently attractive that
extensive efforts are being put into further developing these processes. It is not yet clear
how far these developments will go, but as designers and manufacturers become more
familiar with the advanced textile techniques on offer, the use of these techniques will
become more commonplace.