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Boeing 787 Dreamliner Represents Composites Revolution - 2007-06-04 00:00:00 | Design News Page 1 of 4 Boeing 787 Dreamliner Represents Composites Revolution Extensive use of plastic composites in the Boeing 787 Dreamliner reduces weight and allows new design concepts Doug Smock, Contributing Editor -- Design News, June 3, 2007 When Boeing first considered extensive use of structural composites on the 787 Dreamliner, its engineers knew intuitively the epoxy/carbon fiber matrices would reduce
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   Advertisement Boeing 787 Dreamliner Represents Composites Revolution Extensive use of plastic composites in the Boeing 787 Dreamliner reduces weight and allows new design concepts Doug Smock, Contributing Editor -- Design News, June 3, 2007  When Boeing first considered extensive use of structural composites on the 787 Dreamliner , its engineers knew intuitively the epoxy/carbon fiber matrices would reduceweight significantly, allowing fuel savings and extended flying range. But after an intensive early look at composites, they realized fundamental design changes werepossible 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 timesthan 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 thedevelopment 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 todeal 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 wentdown 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 oftechnology integration on the 787 and former chief engineer for all materials technology at Boeing. “We knew the things like dimensional stability. We knew howcomposites 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 smallerparts 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 adeparture 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 Torayestimated 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 whichare 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 inthat time period for carbon fiber products are approaching a billion dollars. Expansions are coming in the U.S. (Tacoma, WA and Decatur, AL), as well as in France andJapan. Demand for PAN ( polyacrylonitrile )-based carbon fiber is growing 15 percent a year, driven now by the 787. Later growth will come from full-scale penetration ofthe auto market and energy-related applications such as CNG tanks. Mass Production Issues  Production processes for composites are significantly slower than they are for thermoplastics. “We have had no applications (before the Dreamliner ) with high volumes,”says Miller. “The composites industry has never had to deal with this before. That was a mountain we had to climb.”Traditional machine tool producers provided the most important solutions, in Miller’s view. One example is Cincinnati Machine Co . which is supplying new tape layersand fiber placement systems for the Dreamliner 787. “High-speed precision lay-up helps accelerate work flow to shorten build schedules and reduce work in processcosts,” says Randy Kappesser, general manager of composites for Cincinnati Machines. The newest equipment can lay up tape over complex geometric shapes usingproprietary software programs translated from CAD and laminate data. The software allows for offline part programming and simulating, including collision interference.Reinforcing fibers are oriented in specific directions in the resin prepreg to deliver maximum strength only in the direction that is needed. A prepreg refers to fibermatrices already infused with resin.Tools presented a bigger problem because of their size (as large as the airplane) and the evolution of the technology. Previously, composite tools had primarily beenprovided for boatbuilding, which is not a mass production industry.“The technology area still playing out is tooling,” says Miller. “Left to its own devices, composite tooling can be fairly elegant or – if you’re not paying attention to it – itcan be very clumsy and heavy … We had to meet with our technology partners up front to make sure the technology was mature enough to meet our productionschedules.”The gold standard in materials of construction for large composites tools has been an iron-nickel alloy called Invar , which is well-suited because of its controlled coefficient of thermal expansion (CTE). One problem with Invar is it does not lend itself well to lean manufacturing systems that have been a major goal at Boeing forseveral years. The main alternative is “soft” tooling, which is also made from composite materials. Aluminum is a mismatch because of its CTE. Softtooling developed abad reputation because of problems with the B2 “stealth” bomber program.The tooling technology for the Dreamliner is extremely proprietary, but a few details have leaked about a company called Janicki Industries of Seedro-Wooley, WA.Janicki, a long-time yacht builder, has developed new soft tooling for the Dreamliner that has been a success except for one well-publicized mishap , when an error in aresin formulation led to leaking and a damaged mandrel.“The innovation is not just in the materials, but in how they build the tooling,” says Miller. Janicki, for example, custom built three 5-axis CNC mills that have envelopesizes as large as 88 x 19 x 8 ft and accuracies to ±003 inches. More Than Just Weight   Page 1 of 4Boeing 787 Dreamliner Represents Composites Revolution -2007-06-04 00:00:00 | Design News18/08/2010  Composites are worth the effort and are clearly on a fast track in the aircraft industry . The advantages go beyond weight savings. “We’re seeing increasingly practicalways to integrate functions into a single system,” says Miller. “Your structural system can also be a part of your acoustic damping system. It can also be a part of yourthermal transfer system and your electrical system. The use of composites will grow because it’s not just about the structure any more.That’s not all. The superior strength of the composite fuselage will allow higher pressurization in the passenger cabin, making it easier to control temperature, humidityand ventilation. Composite materials are also more durable than aluminum, because of corrosion and fatigue benefits, as well as a dramatic reduction in fasteners. Thestructure of the 787 is essentially one giant macromolecule – everything is fastened through cross-linked chemical bonds reinforced with carbon fiber. “Early on, wemade a decision to do a one-piece barrel,” says Miller. “We don’t have lap joints because we wrap them.”The benefits of composites grow as Boeing engineers gain more experience.“We discovered how to make better window frames, and when we did we changed the load transfer characteristics of the fuselage in that area,” says Miller. “Thatallowed us to go back to the one-piece barrel and take more weight out of that part of the design. We ended up saving three times what we were on the srcinal design.”Another benefit comes from extended lamellar flow (1.5 cubits) at the point where metal meets plastic: integration of the inlet of the Nacelle (engine housing) with thestructure of the Nacelle. Boeing estimates the savings at 20,000 gal of fuel/year —just for that design enhancement.“There is a giant coalescence of manufacturing technology, materials technology and forming that might actually allow us to make another jump in aerodynamicperformance,” says Miller. What are the Downsides to Composites?  They don’t corrode, but they do undergo a photooxidation process. As a result the composites must be painted. And therein lies another Dreamliner technology story.“We’ve come up with an intermediate barrier coating,” says Miller. “Our customers can strip or change the colors of the paint without having to go all the way down tothe composite. That means they don’t have to sand.”Another issue isn’t so much a downside as it is a difference. Composite structures require you to approach thermal and electrical management differently fromaluminum, which has intrinsically higher electrical and thermal conductivity. How you move current from shorts, for example, is notsomething you have to think as muchabout in an aluminum structure. ”We’re a lot smarter about how we attack these issues than we were three years ago,” says Miller.Who owns all of the technology developed for the Dreamliner , considering the huge global supply chain involved? “It depends on who pays for it,” says Miller. “If we paidfor it, we probably own it and we may share it within the program.” If a supplier is contributing its own intellectualproperty, then the technology probably would be ownedby the supplier. All of the major partners have their own extensive R&D programs, and obviously want to be able to leverage some of their know-how with other aircraft  building programs.That’s one reason why Boeing is very secretive about specific technology partners, such as tool makers. Any release of information by suppliers to media is carefullycontrolled by Boeing, as well. Beyond Composites There are also breakthroughs in titanium, aluminum, cool plastics   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, othermaterials 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 greatadvantage 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 withadditional 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, nyloncan improve economics while liquid crystal polymer can improveproperties. They are typically loaded 30 to 40 percent with thermally conductive materials.Suppliers of thermally conductive thermoplastics include LNP Engineering Plastics (GE Plastics), RTP , Cool Plastics and DuPont . On the thermoset side, suppliers include Epoxies, Etc.  “Their thermal properties and other nonmetallic properties are really causing us to think differently about how we remove heat from airplanes,” says Dr. Alan G. Miller, director oftechnology integration on the Dreamliner . Other new materials’ highlights on the ground-breaking aircraft are:   Titanium. The Dreamliner is the first big user of a new advanced alloy titanium in the aircraft industry . “You can really increase strength and get really high toughness,” says Miller.The new grade, designated 5553 (Ti-5Al-5V-5Mo-3Cr), supersedes another high-strength alloy, 1023 ( Ti-10V-2Fe-3Al ). Miller says Boeing is doing a lot of work collaboratively withthe Russian titanium industry. According to the Moscow Times , Boeing is committed to purchase $18 billion of Russian titanium over 30 years. Last August Boeing announced a50/50 joint venture with VSMPO-AVISMA to produce rough machined titanium forgings for the Dreamliner . Of course, politics are involved. Boeing wants to win more business inRussia and Russia would like Boeing to invest in its aircraft industry . Typically, titanium has been used in engine applications for rotors, compressor blades, hydraulic systemcomponents and nacelles. Boeing will also use Alcoa’s high-pressure titanium hydraulic adapter s, which are said to provide up to a 49 percent weight savings over the previousdesign for this application. Each aircraft is expected to use more than 120 of these parts. Aluminum. New technologies are emerging for extrusions in plates in aluminum-lithium alloys that intrigue Boeing’s Miller. It’s well known that aluminum-lithium alloys have lowerdensity, good and often higher strength than conventional aluminum alloys, and provide higher modulus, and therefore, enable weight savings.” The trick is that you have to be verycautious in design so that you are using them in a way that make economic sense,” comments Miller. “This is not a technology push; it’s a business proposition. It has to buy its wayon to the aircraft .”Thermally conductive plastics offer significant improvements over conventional plastics: Page 2 of 4Boeing 787 Dreamliner Represents Composites Revolution -2007-06-04 00:00:00 | Design News18/08/2010  NOTE: W/mK stands for watts per meter Kelvin. Visit  Design News' 787 Dreamliner coverage page  for more stories and podcasts on Boeing's newest  aircraft  !  RELATED CONTENT TOPICSMORE BY THIS AUTHOR PARTNER ZONE » SUBMIT FEEDBACK   I designed with composites years ago. I learned early on a critical design issue. Composites are just reinforced plastic resin. Plastic resin contains plasticizers to make it tough. Plasticizers out gas over TIME becoming brittle. The tensile strength curves for composites slide down to zero on a TIME scale. That is why the rudders on Airbus A305 aircraft are breaking off in flight. 3 so far, maybe more like the two recent aircraft that crashed without cause. I am a pilot. I have inspected full composite airframes in the shop. After 700 hours, a composite airframe is full of cracks. Not so for thousands of hours with aluminum or titanium parts. Yes,they can crack over a long period of time, but mechanics detect the cracks before failure during proscribed inspections. Composite aircraft fail without warning and usually fatally. Non-destructive inspections can not work. I don't fly on A305's and I will not fly on the 787. Lightning strikes and time will bring it down no matter what you try to do. It is an engineering certainty.   Jack Wilkerson - 2009-21-9 15:10:10 EDT    HI This is rohidas Durgekar. im a plastic tool engg. we are manufacturing injection mould ,My Question is if we use reinforced carbon plastic for air craft their may be a chances of brackage or some thing , Due to heat it may melt or Due to high force ofwind if act on perticular component their may be a chance of cracking , any sollution for that,i dont have that much of experince in plastic. can tell me something on that - 2008-6-5 02:00:00 EDT    » SUBMIT FEEDBACK   TALKBACK Boeing Develops Technologies to Recycle Carbon Fibers 06/21/2010 Dreamliner Design Modification Is 'On Track' 10/18/2009 Aircraft Materials' Battle Heats up 08/02/2010 Boeing Makes New Design Fix on Troubled Dreamliner 08/17/2009 Boeing 787 Dreamliner Completes First Engine Runs 06/01/2009 Page 3 of 4Boeing 787 Dreamliner Represents Composites Revolution -2007-06-04 00:00:00 | Design News18/08/2010  Featured Company  Avnet One of the world's largest global distributors of electronic parts, enterprise computing and storage products and embedded subsystems. Avnet provides a vital linkin the technology supply chain. Market needs and trends drive Avnet's product and...more  Most Recent Resources BOKER’S FREE 2010 WASHER CATALOG   Load, Pressure and Torque: Sensor Selection, Technology and...   LightMatters: Cell Phone Projection   The Top Challenges When Designing Rapid Injection Molding Prototypes...   What is Additive Fabrication?   DN MarketplaceObsolete Electronic Component Supplier-Stock Check  Use our Global Part Search Utility to locate hard to find, obsolete, electronic components. IT Training Programs  Get The It Skills That Gets Jobs! Further Your Career Today Obsolete Electronic Component Supplier-Check Stock  Use our Global Part Search Utility to easily locate hard to find, obsolete electronic components. Spice Circuit Simulation  5Spice - easy to use, affordable. User expandable model Library. Download Demo! KXUSB-150 USB Isolator  Protect your PC! Provides 2kV isolation for standard USB devices. Buy a Link Now Resource Center   Browse Categories   Browse Companies     Page 4 of 4Boeing 787 Dreamliner Represents Composites Revolution -2007-06-04 00:00:00 | Design News18/08/2010

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