Since 1991, the Cooperative Research Centre for Advanced Composite Structures (CRC-ACS), in Melbourne, has been looking into more cost effective methods of using carbon-fibre reinforced polymers.
The research centre designs, manufactures and tests composite materials and structures for a range of applications, primarily in aerospace, but also in defence and maritime industries.
In more recent years, the centre has contributed to progressive developments in other industries for applications including bridges, buildings, wind turbine blades, commercial vehicles, and has recently assisted in the development of the next generation of bicycle frames for elite cyclists at the Australian Institute of Sport.
Ian Crouch, business development manager at CRC-ACS, defines advanced composites as a combination of fibre reinforcement material, such as carbon fibre or glass fibre, in a polymer matrix.
Crouch says that standard practice over the last thirty years, and the ‘building block’ for composite aerospace components has been the use of ‘pre-preg’ materials. “These are single layers of highly-engineered fabrics, woven forms of glass or carbon fibres, which have been pre-impregnated with resin, normally an epoxy resin, which is partly cured.
“As sheets of material, they are flexible, pliable and easy to use, but the manufacturing process is very labour intensive relying on precision hand lay-up operations prior to vacuum bagging and using an autoclave to finally cure the part.”
The alternative liquid moulding technologies that the team at the CRC-ACS has been developing are less expensive in terms of materials, labour, and/or capital equipment. As a result, Hawker de Havilland, Australia’s prime aerospace manufacturing company, has adopted many of these alternative practices.
The CRC-ACS has an extensive client base and is conducting ongoing research and development activities related to Boeing’s new 7E7 aircraft, various Airbus programs, as well as military projects like the F111 and the JSF program. It also carries out work for the US Office of Naval Research.
According to Crouch one of the spin-off technologies coming out of the core research program of the CRC-ACS has been the development of a one-shot process for the production of fire-resistant panels using ‘3D’ fabrics.
These fabrics consist of two layers of woven fabric which have additional fibres, integrally woven into the fabric, which connect the two layers together. When the dry fabric is placed in a closed mould and evacuated, phenolic resin is sucked into the fabric, wetting out the surface layers.
As the resin continues to be drawn into the part, excess resin converts into phenolic foam. The result is a light-weight, foam-filled sandwich panel with excellent fire performance and delamination resistance. As an optional extra, such panels can be produced, via the single-shot process, with any type of surface veneer, whether it be stainless steel sheet, aluminium plate or additional layers of composite materials.
This unique process has been patented and an exclusive manufacturing licence set up with the Sydney-based company, Australian Urethane and Styrene. The process is being fully commercialised and will supply panelling to the maritime, building and construction industries.
Crouch says that the CRC-ACS has received funding from the commonwealth for a further seven years and will continue to work with both industry and other research organisations to develop more affordable composite materials, processes and design methodologies.