The adoption of advanced composite materials for aerospace applications has been growing steadily since the early 1980s and the reason is clear – they make aircraft lighter, stronger and more durable than their counterparts such as heavy metals. Today, their adoption is skyrocketing with composites comprising more than 50% of an aircraft’s primary structure, such as the Airbus A350 XWB. It is believed that future commercial and defense aircraft may become more than 80% composite as demand grows for more fuel-efficient aircraft generating fewer emissions.
At Hexcel, we are leaders in developing and manufacturing these advanced materials, and we have a long history serving the aerospace and industrial markets with carbon fiber, honeycomb core, and other engineered materials. For composite intensive air vehicles such as the A350 and the Lockheed Martin F-35, the supply chain and infrastructure are set up to produce these systems at a rate of tens of aircraft per month. For primary structure, the composite components are generally manufactured with legacy processes that include hand layup, automated layup with AFP/ATL systems, and autoclave curing. These processes are adequate to produce the volumes currently required by commercial and defense aviation platforms.
However, some emerging markets are projecting significantly higher build rates – perhaps more than a hundred vehicles per month. This includes the Advanced Air Mobility (AAM) market which is projecting volumes in line with high-end automobile production. It also includes the Unmanned Aerial Vehicle (UAV) market where the defense industry is planning for UAV swarms and attritable systems with only a single mission use that would require production volumes in the hundreds or even thousands per month. These volumes will significantly strain existing supply chain and manufacturing processes, and that is pushing the entire composites eco-system to develop, certify, and implement material systems and manufacturing processes that can meet the projected demand.
There are material systems that have been developed over the years for high-rate production of composites, but those have been primarily in industries other than aerospace. The challenge now is to enhance these systems and certify them for aerospace use, both for passenger-carrying and unmanned systems. At Hexcel, we forecast demand for material solutions that will satisfy the production volume demand from these emerging markets as follows:
Similar to those currently used for automotive and consumer products applications. Curing can occur in a few minutes in compression molding and does not require an autoclave. [what can we say about our current R&T efforts in this area?] Hexcel is at the forefront of developing novel resin chemistries, that deliver improved thermal and mechanical performance combined with faster processing capabilities. Processing times have been reduced to 10s of seconds in some cases!
Dry fiber preforms are infused with resins under heat and pressure. Dry fiber systems such as Hexcel HiMax® and HiTape® allow for automation in the preforming operation and then direct compatibility with Hexcel infusion resins. Again, Hexcel is developing innovative chemistries and curatives that deliver enhanced performance and are tailored in terms of cure temperatures and condition as needed.
Thermoplastics can be stored indefinitely at room temperature and can be consolidated in seconds, are well-suited to automation, add toughness when compared to thermoset systems, and can be more easily recycled. Hexcel is developing innovative prerpregging technology, designed to deliver state of the art performance and product consistency to the industry. Hexcel’s partnership with Arkema is helping to leverage synergies from both companies to deliver this technology.
For complicated geometric parts such as brackets, fixtures, and ducting, additive manufacturing with carbon-fiber/thermoplastic systems can produce at high volumes – in fact, hundreds of parts per month at an economical price with a quick turnaround. Hexcel is leading the way in additive layer manufacturing using state of the art thermoplastic polymer technology and equipment.
In January 2020, Hexcel presented a composite materials outlook for the Advanced Air Mobility market, during the Vertical Flight Society Transformative Vertical Flight conference. We said the materials strategy for this space will coalesce at the intersection of automotive resin technology and aerospace pedigree performance. Since that time, we have seen several announcements from automotive companies that are investing in the AAM space, either through collaboration with start-ups, or setting up their own business units. The automotive industry has extensive experience in producing large volumes of vehicles efficiently and cost effectively. The AAM market is bringing together the aerospace and automotive industries which should lead to overall improvements in composite structures manufacturing efficiency. Moreover, it should open up both the aerospace and automotive markets for the use of more composite materials which will ultimately benefit the consumers of air and ground transportation.
About the author
Dr. Robert Yancey has filled numerous roles in his career including research, technology development, sales, management, business development, and executive roles. He currently leads business development for Hexcel in the Americas which includes advanced materials, manufacturing, and engineered products. He has a technical background in composite materials, composite mechanics and micromechanics, design optimization, additive manufacturing, finite element modeling, and nondestructive evaluation. He holds a B.S. degree in Aeronautics and Astronautics from MIT, an M.S. degree in Engineering Mechanics from Virginia Tech, and a Ph.D. in Materials Engineering from the University of Dayton. He is an AIAA Associate Technical Fellow and Industry 4.0 Emerging Technologies Lead for SAMPE.