When Boeing first considered extensive use of structural composites on the 787 Dreamliner, its engineers knew intuitively the epoxy/carbon fiber matrices would reduce weight significantly, allowing fuel savings and extended flying range. But after an intensive early look at composites, they realized fundamental design changes were possible that would allow functional systems integration, as well as changes in lamellar flow that would improve aerodynamics.
From a materials’ point of view, the 787 Dreamliner is one of the most revolutionary leaps in the history of manufacturing.
But in order to meet an ambitious delivery schedule – the first delivery is scheduled for May 2008 – there were tremendous hurdles to jump:
No one ever attempted to mass produce very large carbon-reinforced plastic structures, which are thermoset materials with significantly slower processing times than thermoplastics,
The critical tooling for such large sections was still very much in the development stage and, in fact, represented one of the few, small stumbles in the development program,
New coatings had to be developed to deal with the crack propagation issues, which are not a factor with aluminum. Engineers had to devise different systems to deal with electrical shorts because composites are not electrically conductive.
One area that was not new was the materials’ technology. “When we made the decision on composites’ use in the wings, fuselage, floor beams and so on, we went down a path based on a material that we had already had a significant amount of production experience with on the Triple 7,” says Dr. Alan G. Miller, director of technology integration on the 787 and former chief engineer for all materials technology at Boeing. “We knew the things like dimensional stability. We knew how composites impacted the manufacturing flows. We had a lot of design allowables databases. We had a lot of confidence from our customers.”
The Boeing 777 is 9 percent composites by weight, compared to 50 percent for the Boeing 787. Throughout the life of the 777, the Carbon-reinforced plastic materials (composites) were enhanced in terms of their properties, manufacturing and cost structure.
There are several different types of composites used on the 787, including bismaleimide, depending on specific applications requirements. There are several smaller parts made from discontinuous fibers that can be molded into odd shapes. There is also extensive use of thermoplastics in the interior of the aircraft, but that’s not a departure from previous designs.
All of the composites are supplied by Toray Industries, the world’s largest producer of carbon fiber. Since 2004, Boeing has placed composites orders with Toray estimated at more than $6 billion, creating pressure on prices and supplies for other users. The estimate was based on projected production as of 2006, numbers which are already out-of-date because of the spectacular success of the 787.
At the end of 2003, Toray had capacity to produce 7,300 metric tons of carbon fiber products. By this summer, capacity will reach 13,900 metric tons. Its investment in that time period for carbon fiber products are approaching a billion dollars. Expansions are coming in the U.S. (Tacoma, WA