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.
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.
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.
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.
Composites aren’t the only materials’ news in the 787 Dreamliner. While composites represent 50 percent by weight (80 percent by volume) of the Dreamliner structure, other materials represented are aluminum, 20 percent; titanium, 15 percent; steel, 10 percent and 5 percent, other. Most notable among the “other” is the first-time widespread use in aircraft structures of plastic heat sinks. That’s right – plastic heat sinks. Plastics that are highly loaded with heat-removing materials such as carbon or ceramics have been around for a while, but have not yet penetrated the aircraft market. Their great advantage is their ability to be molded into net shapes. The economics for plastics can be favorable depending on total tooling and finishing costs. They can be designed with additional surface areas as fins and ribs to improve convective heat transfer. Costs and properties can be balanced depending on which engineering thermoplastics are used. For example, nylon can improve economics while liquid crystal polymer can improve properties. They are typically loaded 30 to 40 percent with thermally conductive materials.
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