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Composite Materials: Building the Next Generation of Passenger Aircraft

08/21/2013
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Moving Beyond Metals

The Japan Aerospace Exploration Agency (JAXA), Japan’s equivalent of NASA, has made a name for itself internationally in recent years with such high-profile successes as the asteroid explorerHayabusa and the Kibo module that has been making important contributions to experiments on the International Space Station. But the agency’s activities are not restricted to space exploration. JAXA is also home to Japan’s only aircraft research center, working on everything from environmentally friendly engines and supersonic aircraft to carrying out safety tests with state-of-the-art simulators.

JAXA is Japan’s leading research institute in the fields of space and aviation technology. The cutting-edge technology developed for use in aircraft application promises to unlock new potential in a wide variety of fields.

One development that has made the news in Japan recently is the Mitsubishi Regional Jet, or MRJ, developed by the Mitsubishi Aircraft Corporation. This is the first passenger airplane to be designed and produced in Japan for 50 years. The fuselage of the plane uses a new type of composite material developed by the Civil Transport Team that is part of JAXA’s Aviation Program Group.

When the Wright brothers made the first successful manned flight in 1903, their pioneering plane was built of wood, steel wire, and cloth. Later aircraft used aluminum alloys and titanium. In recent years composite materials, and carbon fiber reinforced plastic (CFRP) in particular, have come to play an increasingly important role.

Providing the Materials for Boeing’s Latest Planes

CFRP is made by impregnating a resin (plastic) with carbon fibers that act as a reinforcing material. Carbon fiber is light, with a specific weight one-fourth that of iron, and approximately ten times stronger per unit weight. It is extremely durable and, unlike metal, presents no problems with rust. Boeing’s latest passenger aircraft, the B787, uses Japan-developed CFRP for about half of its structural material. This makes it the world’s first passenger airplane to contain a greater proportion of CFRP than aluminum by structural weight. CFRP is also used in the Mitsubishi Regional Jet and the Airbus A350, scheduled to debut in 2013.

Dr. Ishikawa Takashi, Executive Director of the Aviation Program Group at JAXA, explains the advantages of using CFRP in aircraft.

“First of all, the lighter weight means that the plane consumes less fuel. CFRP also has excellent specific strength and specific stiffness, and it doesn’t rust—so you don’t have to carry out maintenance as often as with conventional materials. This minimizes the toll it takes both on the environment and on the finances of the airline company. The material has advantages for passengers as well. If you use aluminum as the main structural material, the humidity inside the plane needs to be kept at 10% or lower. But thanks to the new material, cabin humidity in the B787 can be increased to nearly 50%. This makes for a much more comfortable environment for passengers.”

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New Methods Reduce Costs

The increasing use of carbon fiber in aircraft manufacturing has seen production increase dramatically over the past 20 years, to 27,000 tons in 2010. Japan is a world leader in carbon fiber production, accounting for a full 70% of the global total. The Ministry of Economy, Trade and Industry expects the size of the world market to reach 125,000 tons in 2020 (roughly 4.5 times the figure for 2010). By 2030, it is hoped that Japan will earn some ¥3 trillion a year from the aircraft industry.

But there are still issues to be overcome—chiefly cost and safety. Carbon fiber has always been more expensive than aluminum alloys. On top of this, thermoplastic particles are added to make an intermediate material known as prepreg (from “pre-impregnanted,” meaning sheets of carbon fibers that have been hardened in advance with a partly cured resin), whose strength makes it ideal for shipment and processing. The prepregs are then placed in a mold and baked (or “cured”) in huge ovens called autoclaves. This fixes them into their final shape. In the case of a plane, the molded piece needs to be large enough to accommodate the main wings. The cost per plane comes in at tens of billions of yen.

To reduce costs, JAXA collaborated with the private sector to develop a new method of manufacture known as vacuum assisted resin transfer molding, or “VaRTM.” Ishikawa describes the new method: “Carbon fiber is placed between sheets of film and the air is removed to create a vacuum. Low viscosity plastic is injected and the fibers are impregnanted with resin. It’s a little bit like the vacuum storage bags used for bedding.”

The main advantage of the VaRTM method is that it does not require the use of an autoclave or similar curing equipment to heat the materials. But this results in a material that is not as strong as that made with the conventional method, using prepregs. Conventional manufacturing methods are therefore more suitable for making airplane fuselages and similar parts.

JAXA therefore came up with a hybrid approach that makes the most of both methods: using prepregs for flat parts with large surface areas and VaRTM materials for the framework and other components with complex shapes, in an attempt to achieve both high quality and low cost.

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Other Applications

Further research is still underway to make absolutely sure of the safety of CFRP. One known issue is the risk of delamination following high impact. This causes the layers of the composite material to separate, leading to a significant loss of mechanical toughness. Because it is still not possible to simulate these conditions satisfactorily with computers, tests to prove that the model meets the safety requirements for certification have to be carried out using actual parts. Making it possible to run these tests on computers would reduce the time and cost of certification, and JAXA is therefore working to create models of failure characteristics.

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Models for collisions with foreign objects, on the other hand, have already been established. Comparisons of test results and computer analyses have shown that almost completely accurate simulations are possible. “These results put us at the very forefront of international research,” Ishikawa says proudly.

Recent research has focused on prepreg materials in which cup-stacked type nanofibers, a type of carbon nanotube, are dispersed in resin. Researchers say that as nanotechnology is used in a wider range of applications, the possibilities for adding new functions onto CFRP will only continue to increase.

Possible uses of the remarkable characteristics of CFRP go far beyond aircraft. In the future, it is hoped that the material will also prove useful in fields such as automobiles, wind turbines, industrial machinery, and shipping. In all these areas, CFRP combines the twin attractions of low environmental impact and economic affordability. Carbon, widely seen as a villain in the problem of global warming, may yet bring ecological as well as economic benefits. It will be fascinating to watch this story unfold.

(Originally written in Japanese by Hayashi Aiko. Photographs by Hans Sautter.)

From Fibers to Finished Composite Components

01/26/2013
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We are SGL Group – The Carbon Company. We encompass the complete value chain of carbon fiber products – from precursor via carbon fibers, fabrics and prepregs to finished CFRP composite parts.

Stitched carbon-fiber fabrics

01/26/2013
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Stitching carbon-fiber preforms with a Keilmann Group RS530 2-needle stitching head. The end-effector is being driven by a Kuka KR100 HA with the L80 extension.

Why the future of aviation needs the Dreamliner | The Japan Times

01/26/2013
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Why the future of aviation needs the Dreamliner | The Japan Times.

LONDON – As Boeing showed off its multibillion-dollar baby on the Dreamliner’s promotional world tour in 2011, one quirky feature was regularly pointed out: a sleekly designed but redundant ashtray, a compliance with regulations laid down in a different age. In the darkest torments of Boeing executives during the 787′s past incident-packed weeks, it may have finally appeared of use: somewhere to enjoy the cigarette of the condemned, a quiet smoke to mask the smell of burning battery.

A little over a week ago, America’s government and air authorities stood shoulder to shoulder with their top exporter, Boeing, to assure the world that the plane was safe after a string of incidents from fuel leaks, windscreen cracks and battery fires. They still say it — only, right now, that no one should fly in it.

By on Jan. 16, a diagnosis of teething problems was no longer enough. The burning battery was back, and Japanese authorities said the latest incident was “highly serious.” Corrosive fluid had leaked down through the state-of-the-art electronics below the cockpit. Hideyo Kosugi, a Japanese safety investigator surveying the All Nippon Airways 787 that had made an emergency landing at Takamatsu Airport, said the stuff had gone right through the floor.

After the Japanese airlines operating almost half of the Dreamliners worldwide decided they could risk it no longer, the U.S. Federal Aviation Administration grounded all 787s in its jurisdiction. From India to Qatar, Poland to Chile and finally Ethiopia, the global fleet was taken out of action, an ignominious fate for a plane that had been so eagerly anticipated for so very long.

In an industry where different models are normally denoted by numbers alone, naming the 787 the Dreamliner was to invite attention: a bold statement that this was to be something fundamentally different. This craft does not simply carry the commercial aspirations of Boeing; it has become symbolic of aviation’s promises for a greener, quieter future.

For passengers, there was the thrill of bigger windows, funky lighting and increased cabin pressure, said to reduce the ill-effects of flying. Thomson, the first U.K. customer, has built an ad campaign around it. But for airlines, the critical selling point was fuel efficiency, where the airline executives’ and the environmentalists’ interests briefly coincide.

While rivals mutter that the aspirations have yet to be matched in operations, the lighter plane promised a 20 percent cut in the soaring fuel bills that have wiped out profits for many airlines.

The Dreamliner also promised a range unique for an aircraft of its size, potentially making direct flights to long-haul destinations viable with fewer passengers, not least, the secondary cities in the emerging BRIC economies — Brazil, Russia, India and China — to which business people here apparently clamor to fly.

Improvements in those spheres are by no means unique to the Dreamliner. But perhaps more than any other plane, it has come to represent the technological innovation that the aviation industry claims will allow it to meet its wider obligations to the world: that we can fly and not fry, even with ever more flights.

A carbon dioxide “road map” produced by Sustainable Aviation, an industry group addressing environmental issues, sees the fuel efficiencies delivered by the 787 and its successors as a way to cut about a third of all projected carbon emissions, a major part of a plan that would let traffic double by 2050 and still meet the emissions targets aviation signed up to in the wake of the Kyoto climate negotiations.

For airports in Britain’s crowded south-east, the Dreamliner is also a name to conjure with. Briefly in operation in Britain since Qatar Airways’ inaugural flight just before Christmas, it claims a “noise footprint” some 60 percent smaller than other planes its size. Around London’s Heathrow, such contours spell votes: Mayor or London Boris Johnson has spoken of 750,000 Londoners having their lives blighted by aircraft noise. As Howard Davies’ commission sits down to reflect over the next two and a half years on the future shape of Britain’s airport capacity, Heathrow will want to demonstrate that noise is not a insurmountable political obstacle. Current proposals from the United Kingdom’s Department for Transport will ramp up the fines for louder planes.

So Boeing’s problems are aviation’s problems too. Little wonder that few airlines, beyond the annoyance of those already operating the now-grounded 787, have offered anything but unqualified support and confidence. With 799 aircraft outstanding, the order book dwarfs the 50 in service. The ambitions of the fleet planners everywhere for new routes and for lower overheads hang on the 787s rolling out of the Seattle factory.

Observers have little doubt that the Dreamliner will fly again. Douglas McNeill, investment director at Charles Stanley, says: “It will get fixed. Boeing just has no alternative — it’s just a question of how much time and money it takes. If it’s just the battery, it could be relatively simple. If it’s an overhaul of the whole onboard power generation, it’s a time-consuming and costly task.”

If safety has always been paramount, the industry is taking absolutely no chances in preserving its proud boast; according to the International Air Transport Association, 2012 was the safest year on record. McNeill dismisses safety fears: “It would be more than odd, it would be astonishing if there was an issue that escaped the hundreds of thousands of hours of testing that Boeing and the FAA carried out. It’s hard to imagine the Dreamliner not re-entering service quickly, but in the worst-case scenario it could have a real impact. It was going to be a big step forward in terms of noise and emissions.”

Not everything hinges on the Dreamliner: Rival Airbus has the A350 coming down the line, also built with composite materials and lithium-ion batteries. While Airbus is quick to point out that its design — and batteries — are very different from those troubling the safety teams examining Boeing’s plane, it has been described as the response to the 787.

There was no hint of schadenfreude from boss Fabrice Bregier at last week’s Toulouse event when Airbus announced a record year for aircraft deliveries — though second to Boeing in orders. In the long term, the efficiencies will come: Concerns about the new technology may again hold up the process more than those worried by climate change or the bottom line would hope. “Airbus and Boeing will need to get these planes into service,” McNeill adds.

Boeing meanwhile has said it will do all it can to restore confidence. Chief executive Jim McNerney pledged to “work around the clock” with investigators, adding: “We will make available the entire resources of the Boeing company to assist.”

For a corporation the size of Boeing, worth around £50 billion even with its shares sliding, the current problems should amount to little more than a spot of turbulence. Airbus quickly recovered confidence and orders despite cracks in the wings of its pioneering A380 in 2011.

From the ashes of its burning battery, the Dreamliner will surely make a phoenix-like return.

Don’t Panic with Mechanics

02/12/2012
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Statika atau Statik adalah mata kuliah yang diberikan di teknik sipil, teknik mesin, teknik penerbangan atau teknik industri pada tahun ke-2. Mata kuliah ini memberikan dasar, teori dan teknik untuk menghitung gaya-gaya, defleksi (lendutan) dan sudut lendutan pada suatu benda (misal: batang kantilever) dan struktur (misal: struktur truss). Statika pada dasarnya telah dipelajari pada mata pelajaran fisika, khususnya mekanika, baik di SMA maupun di tingkat pertama S1. Statika sebenarnya merupakan bagian  dari Mekanika Teknik.

Dapat dipahami bahwa sebagian mahasiswa kesulitan dengan statika. Satu resep yang selalu diberikan agar dapat menguasai Statika adalah rajin mengerjakan soal. Ini kurang tepat. Sebelum mengerjakan soal, seseorang harus menguasai dulu konsep-konsepnya. Sayangnya, konsep-konsep di buku kadang tidak dijelaskan dengan baik. Baik karena alih bahasa yang kurang baik, ilustrasi yang terlalu kompleks, rumus penurunan yang kurang rinci. Intinya, buku yang kurang jelas akan membuat konsep-konsep statika jadi tidak jelas pula. Belum lagi diperburuk oleh dosen yang kurang pandai mengajar (terlalu banyak materi, kurang komunikatif, kurang pandai bercerita). Ini tidak membuat mahasiswa rajin. Oleh sebab itu, memilih buku yang tepat adalah awal dalam penguasaan statika. Selanjutnya, baru penguasaan konsep dan pengerjaan soal. Jangan mengandalkan dosen dalam memberikan pencerahan mengenai subyek-subyek dalam statika. Belajarlah memahami suatu topik dengan pengertian sendiri. Jika kurang jelas, bertanyalah kepada kawan yang lebih bisa, atau dosen di ruangannya. Jadi lebih intensif.

Saya pernah menemui dosen yang begini: tidak mampu menjelaskan teorema matematika dengan bahasa yang sederhana, yang mudah ditangkap oleh mahasiswa. Ketika diminta menjelaskan soal angka rata-rata, sang dosen membuat perhitungan angka rata-rata jadi tambah kabur. Biasanya hal itu diwarnai dengan rumus-rumus yang kompleks. Rumus kompleks boleh diberikan, tetapi setelah menyampaikan intisari suatu topik. Di sebelah kanan, seorang ibu mengatakan: “Kenapa kamu tidak mengatakan kepada anak itu bahwa kamu sedang ngomongin angka rata-rata (mittelwert)?!”

Intinya: dalam kuliah Statika, seseorang harus mengerti prinsipnya terlebih dahulu dulu (dengan matematika yang sederhana). Kemudian dilanjutkan dengan prosedur pengerjaan, dan berlatih mengerjakan soal.

Satu buku yang unik dan berisi statika, mekanika bahan dan dinamika berjudul Don’t Panic with Mechanics. Isinya lengkap, tidak terlalu banyak rumus, banyak kartunnya. Buku ini ditulis dua ilmuwan Jerman, Romberg dan Heinrichs. Bukunya masih fase eksperimental, mereka bilang. Dalam pengantarnya (yang relaks dan lucu), Dr Heinrichs mengatakan bahwa rekannya Dr Romberg adalah seorang yang mudah akrab (sociable), lucu namun pendek. Dr Romberg tak mampu membalas “pujian” itu jadi ia hanya mengatakan bahwa Dr Heinrichs adalah ilmuwan yang unggul namun membosankan.

Bagi yang berprofesi sebagai dosen, bisa membaca buku ini dan memasukkan kartun-kartunnya ke dalam slide yang dipakai. Bagi mereka yang sedang mengambil kuliah Statika atau Mektek cobalah baca buku ini. Ada banyak contoh soal di bagian akhir; supaya lebih mengerti prinsip-prinsipnya.

Komposit pada Struktur Pesawat Penumpang

05/03/2010
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Pabrik pesawat terbang memakai serat karbon/resin plastik (CFRP) untuk sebagian dari strukturnya. Airbus A380 memakai 22% komposit sedangkan dan Boeing B787 memakai 50%.

Carbon fibers lighten loads

04/04/2010
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The Asahi Shimbun, 1 April 2010

Chemical maker Teijin Ltd. on Tuesday unveiled its latest lightweight PU_PA electric vehicle built with carbon-fiber materials developed by the company. The two-seater weighs in at just 437 kilograms, about half that of rival electric vehicles. Carbon fiber, at one-fifth the weight of steel but 10 times stronger, is used for the vehicle body. Special plastics are used for the windows. Adding air conditioning and other extras would raise the total weight of a PU_PA car to about 550 kg. Its price is a hefty 80 million yen ($865,000). About 80 percent of the concept car is made with Teijin materials. It can travel about 100 kilometers on a single battery charge and, when equipped with safety features such as air bags, can be used on the street. The company aims to provide carbon materials to other carmakers, significantly widening the market within five to 10 years.

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