The implications of the Phase I results are driving Phase II of the project, and could ultimately lead to a decrease in cost for carbon fibre composite structures, making them more amenable for adoption in the automotive and other high volume industries, reduce embodied energy, and lead to a creation of jobs in the industry.
This material created through this IACMI project combines Fibrtec’s flexible coated tow, Fibrflex, with DuPont’s Rapid Fabric Formation (RFF) technology and a proprietary DuPont polyamide resin, supported by Purdue University’s modelling and characterisation capabilities. The coated tow material is a partially impregnated carbon fibre/polyamide composite tow where the carbon fibre is not fully wetted with the polyamide, yielding a more flexible tow material than one that is fully impregnated. The RFF process is said to be an ultra-fast way of manufacturing fabrics with tows in varying orientations without the need to lift the tow during processing. Experiments, modelling and simulations have shown that this process/materials combination is a potential method for producing lower cost continuous fibre reinforced polymer (CFRP) thermoplastic materials that conform well during moulding with outstanding physical properties.
“Fibrtec’s contribution of its globally differentiated thermoplastic composites to this IACMI Phase I joint project with DuPont and Purdue University has helped to deliver breakthrough results on the IACMI goals,” says Robert Davies, Fibrtec’s Chief Executive Officer. “Tapping into the innovation of small and medium sized organizations (SMEs), like Fibrtec, and the forging of public/private partnerships through IACMI’s framework is accelerating the insertion of structural composites in the automotive industry. It is a fantastic opportunity for companies like Fibrtec to have access to world-class resources not normally available to them and we look forward to continuing Phase II.”
The objective of this project is to reduce the cost of manufacture of carbon fibre reinforced polymer composites by using a near net shape process such as automated fibre placement (AFP) on a relatively inexpensive carbon fibre/polymer tow-preg. The coated tows are easily manipulated, and the resulting pseudo-fabrics are readily draped and conform easily during moulding without shear locking. The project partners project that with this strategy, the process would be able to use the expensive carbon fibre only where it is required, reducing the carbon fibre waste by up to 30% and creating fibre preforms that predictably deform during compression prior to moulding.
The Phase I project conclusion resulted in better than expected outcomes with embodied energy being reduced by more than 40% using this processing scheme.
“This project addresses some of the most challenging aspects of composites manufacturing and commercial adoption in high volume market applications,” reports Jan Sawgle, Program Manager DuPont Transportation and Advanced Polymers. “Phase I completion signals a step forward in demonstrating a significant impact in the ability to make lower cost parts with the design freedom to meet performance requirements of challenging applications. This was one of the earliest projects launched by IACMI and it serves as a great example of collaboration and partnering to accelerate innovation. We look forward to continuing our progress in Phase II.”
“The synergy between Purdue, Fibrtec and DuPont on this project demonstrates the power of public-private partnerships in fostering innovation and delivering novel solutions to real-world problems,” adds Michael Bogdanor, director of the Composites Design Studio in the Purdue Composites Manufacturing and Simulation Centre. “In this project, we focused on manufacturing informed performance, which is of critical importance in the design of composite components and structures. Phase I of this project was instructive in developing new simulation tools to be able to predict the behaviour of the RFF and FibrFlex technologies. This resulted in new methods to predict the behaviour of the material system in manufacturing as well as the ultimate performance of parts.”
“We are pleased by the outcomes of Phase I and look forward to continued development of these advanced carbon fibre composite materials,” concludes IACMI Chief Executive Office, John A. Hopkins. “Through the second phase of this project we will more fully characterise these novel carbon fibre thermoplastic prepreg forms and validate their use in moulding processes suitable for high-rate, cost-sensitive applications. This will showcase their suitability for large-scale deployment, especially in the automotive industry, which is an important part of our long-term goals to reduce energy use.”
This project offers a new CFRP manufacturing process when compared to the two other typically deployed processes which have significant drawbacks that limit their mainstream, high volume use in the automotive and aerospace industries. One mainstream current technique weaves dry carbon fibre tows into a fabric, layers the fabrics with thermoplastic resin films, and subsequently heats and compresses them into a well-consolidated composite. While this method is ultimately effective in creating a carbon fibre fabric, the process has several drawbacks. One drawback is that the carbon fibres often break during the weaving process, releasing short, conductive carbon fibre strands into the local environment. Therefore, the surrounding looms and equipment must be electrically isolated. Another drawback is the relatively slow speed which is associated with this traditional process. Creating carbon fibre composites through this weaving method is roughly one-third the speed of that required to make glass fibre-based fabrics.
A second typical technique is the impregnation and flattening of carbon fibre tows with a thermoplastic resin to make a low-void, fully consolidated composite tape. These tapes are then woven or placed and tacked to form a fabric, which is then rapidly consolidated into the final composite part. A major issue with this process is the handling of the UD tapes because they are stiff and brittle, and therefore can fracture when bent to tight radii at room temperature. This stiffness property makes fabric formation from tapes a slow and expensive process.
The conclusion of Phase I of the DuPont, Fibrtec project is said to validate the advancements that can be made in the carbon fibre composites production field, and reveals new opportunities for the application of carbon fibre composites into the automotive and aerospace industries as carbon fibre composites become easier and safer to produce making them more affordable, and viable for mass production.