‘But How Can We Make Something Useful Out of Black String?’ The Development of Carbon Fibre Composites Manufacturing (1965–2015)

Abstract

Abstract.This chapter looks at how the manufacturing community responded to the invention of carbon fibres, the first practical, high-modulus, reinforcement to be available as continuous fibres; largely through the lens of the author's personal experience. Whilst it seems axiomatic to us today that we use continuous fibres, most of the composites applications in 1965 used short fibres, for example chopped glass, asbestos, whiskers or linen fibres. To a large extent the narrative of carbon fibre composites manufacturing is the story of how to manipulate continuous fibres into complex geometries; and how to do that cost-effectively without introducing strength reducing defects. Until very recently, when the manufacturing and structural integrity communities have started to interact much more, there has tended to be an almost complete disconnect between the materials, design and manufacturing worlds. This has been the case as much in industry as it has in academia and seems to have been the norm since the very beginnings of the application of carbon fibre composites. The difficulties inherent in manufacturing geometrically complex parts were identified very early in the history of carbon fibre composites. However, it has proven to be very challenging to go beyond identifying problem issues to actually solving them, and that process is by no means complete. There are signs that the composites community may finally be on the right track, with some recent successes pointing towards research directions where design and manufacturing approaches can be unified to deliver reliable and cost-effective parts -only 50 years after the process started.

Automated layup and forming of prepreg laminates

“…There are automated layup techniques that are suitable for large structures with simple geometries, but the current automation alternatives struggle with problems related to affordability, process reliability and overall productivity [12,13]. These automated alternatives are limited in terms of part complexity and size [16,17], and there are a number of products that cannot be efficiently manufactured using the current methods for automated layup [18]. Developing automated solutions for the manufacturing of composite products made from prepreg requires a thorough understanding of the raw material, as well as an in-depth understanding of the manufacturing processes.…”

“…For the layup process, the plies must be stacked in the correct sequence and according to specifications on allowable gaps and overlaps between prepreg plies, and the position and orientation of the plies must also be to specification [3,[67][68][69][70][71]. There are also requirements on fiber orientation: the industrial norm generally allows a ±2° or ±3° fiber orientation deviation compared to the drawing nominal [16,67]. However, controlling the fiber direction is difficult and many complex parts only have a single control rosette showing the four main directions to compare with [16,67].…”

“…There are also requirements on fiber orientation: the industrial norm generally allows a ±2° or ±3° fiber orientation deviation compared to the drawing nominal [16,67]. However, controlling the fiber direction is difficult and many complex parts only have a single control rosette showing the four main directions to compare with [16,67]. The layup must be made so that no air is trapped between the plies, as this causes porosity and poor material properties in the cured product [72].…”

“…Both types of systems deposit prepreg tape layer by layer on a mold; the major difference between the two is the width of the deposited tape. The first developments of ATL technologies came in the late 1960s, and the oldest patent in the area is from 1967 [16]. Research machines were developed in the 1970s.…”

“…AFP offers much lower scrap rates than manual layup, where prepreg plies are cut from broad rolls of prepreg, although the additional cost for slitting the narrow tapes from wide rolls of prepreg can in some cases offset the savings of lower material waste [16].…”