Airbus and MIT look to digital manufacturing to reduce aircraft construction costs

A lego play composite?? Damn cool.... :)

Source : http://www.reinforcedplastics.com/view/36097/airbus-and-mit-look-to-digital-manufacturing-to-reduce-aircraft-construction-costs/

Could composite aerospace structures be assembled much like snap-together building blocks rather than manufactured as large, expensive, one-piece parts? Under a new research agreement Airbus and the Massachusetts Institute of Technology (MIT) will explore the potential of digital manufacturing in aircraft construction.

Aircraft manufacturers are increasingly adopting composite materials to reduce aircraft weight and operating costs. Airbus' latest model, the A350 XWB, is over 50 wt% composite.

Current composite airframe manufacture involves the fabrication of large single-piece parts, an expensive process. (The fuselage of the A350 XWB, for example, is made up of a number of large composite panels which are then joined together.)

The digital material concepts being developed at MIT could lead to lighter weight structures and lower construction and assembly costs.

Composite materials

Airbus will work with MIT’s Center for Bits and Atoms (CBA), which has been developing new methods for manufacturing structures out of carbon fibre reinforced plastic (CFRP). 

CBA Director Neil Gershenfeld and his colleague Kenneth C. Cheung recently published a paper in the journal Science on Reversibly Assembled Cellular Composite Materials. This outlines the assembly of a 3D lattice of mass-produced CFRP parts with integrated mechanical interlocking connections. Cheung produced flat, cross-shaped composite pieces that were clipped into a cubic lattice of octahedral cells, a structure called a 'cuboct.'

The parts form a structure that is 10 times stiffer for a given weight than existing lightweight materials, according to the researchers. The structure can also be disassembled and reassembled easily – such as to repair damage. (The repair of the composite aircraft fuselages now entering service is a challenge facing the aerospace industry).

The individual composite parts can be mass-produced and MIT is developing a robot to assemble them into wings, aircraft fuselages, and other parts. Other applications such as bridge decks are also possible.

Advantages of 'digital composites'

The MIT technique allows much less material to carry a given load. This could reduce the weight of aircraft and other vehicles, which in turn would lower fuel use and operating costs.

The costs of construction and assembly would also be lower.

Unlike conventional composite materials, which tend to fail abruptly and at large scale when stressed to the breaking point, the modular system tends to fail incrementally, the researchers say. This makes it more reliable and easier to repair. 

The possibility of linking a number of parts introduces a new degree of design freedom into composite manufacturing. MIT has shown that by combining different part types, they can make 'morphing' structures with identical geometry but that bend in different ways in response to loads.

This means that instead of moving only at fixed joints, the wing of an aircraft could change shape.

Taper Scarf Removal : Not For Real Man

It is not an art at all. Just a lazy man's work. Although this is preferable in MRO industries, but the quality of the repaired structure already been compromised.

A few cons :

Not applicable to repairs of thick structures 
Some risk of damaging “good” structure within and outside the scarf area

The load designed for each layers of plies orientation is not connected perfectly anymore. It is just more or less, which is not up to the standard for aircraft industries.

For a real man out there, let's go for higher standard!

Composite Step Removal : The Forgotten Art

In composite repair, the removal plies process is the most unpleasant situation and could be hazardous due to dust from the removal. The best practice for this process is still the STEP REMOVAL.

Step removal is the standard requirement in aircraft industries especially for manufacturer. But, most of the MRO players prefer the taper scarf removal which is not very good in quality and load transfer designed for the current structure.

It is the race-against-time which in the end determine either step sanding or taper scarf is preferable.

Most probably, the step removal will be the forgotten art.

Video show of simple step removal using grinding process.

The quality different between step removal and taper scarf will vary greatly when the number of plies removed increases.

But, by using grinder for step removal at certain point can be very impossible to handle. This will limit the repair if the competency is not up to the level required.

The keyword here is 'Competency'.

See the example of 16 plies removal using special techniques from aircraft industries;

So, how to remove 16 plies of composite with this complex configuration?

The keywords here is 'Special Techniques'.

The secret of the forgotten art is safe with us.

The Aircraft Composite Repair Getting Harder and Complicated

It is just a matter of time before the composite repair getting more harder and complex. Until that time only a few can still follow the competency level required by the fast changing industries.

Metal type of repair may become obsolete or at least becoming less and less popular in the next 10-20 years  after this.

Most of the MRO's players prefer a simple composite repair techniques like wet layup and trying to avoid the use of advanced materials like prepreg applications due to high cost of MOQ, storage and short storage life issues.

By doing this, they just buying time before they realize they cannot catch the advanced repair techniques standard for high performance composite set by the manufacturer/OEM.

If this was right, in the nearer future, only manufacturer can repair the high performance composite type. The MRO players need to make collaboration with the manufacturer to set up an integrated Composite Repair Center approved eg by Boeing or Airbus in a region like South East Asia.

This smart collaboration will save money on the advanced facilities and materials and also save time in developing the competency of the people.

Compete or collaborate?

You decide.

Read an interesting news on Boeing concern about the composite repairs;

from : http://www.bloomberg.com/news/2011-10-21/boeing-dreamliner-s-composite-repairs-questioned-by-u-s-agency.html

Boeing Dreamliner Composite Repairs Questioned By U.S. Watchdog

Boeing Co. (BA)’s new 787 Dreamliner, set to fly its first paying passengers next week, faces four “safety-related concerns” about repairs to the composites used for the fuselage and wings, a U.S. agency said.

A review of the Dreamliner, the first airliner built with carbon-fiber reinforced composite plastics instead of metal, was released Oct. 20 by the U.S. Government Accountability Office. The GAO identified four concerns: limited information on the behavior of airplane composite structures; technical issues with the materials’ unique properties; standards for repairs; and training and awareness.

The U.S. Federal Aviation Administration certified the 787 in August following 20 months of flight tests, after requiring that Boeing take extra steps to demonstrate its safety. The GAO was asked by three members of Congress to review the FAA’s certification process and planned oversight once the model enters service, and consulted experts on repair and maintenance.

“None of the experts believed these concerns posed extraordinary safety risks or were insurmountable,” the GAO said in its report. Still, while the FAA is taking action to address the matters, “until these composite airplanes enter service, it is unclear if these actions will be sufficient,” the report said.

The 250-seat Dreamliner uses the lighter-weight composites, new engines and the first all-electric system to help it fly farther with less fuel.

Charter Flight

Chicago-based Boeing delivered the plane last month to its first customer, Tokyo-based All Nippon Airways Co., more than three years late after Boeing struggled with the new materials and manufacturing processes. The Dreamliner is scheduled for a charter flight from Tokyo toHong Kong on Oct. 26 and will enter regular service the following week.

“Regardless of the materials we use, Boeing employs the same rigorous methods to deliver products that are safe for the flying public and efficient for airlines,” said Marc Birtel, a Boeing spokesman in Seattle. “Composite materials have been used in commercial airplanes for decades.

‘‘The concerns in the GAO report are limited to support activities,’’ which already are being addressed through an industrywide effort involving regulators, manufacturers, operators and maintenance and repair organizations, Birtel said.

Boeing has used composites for other airliners before, including the 777, though never for the whole fuselage and wings as in the 787.

Repairs Different

The Dreamliner’s fuselage is made of reinforced carbon fibers spun around a barrel mold and baked, so repairs will be handled differently than with traditional aircraft that are built of riveted aluminum panels.

‘‘The FAA conducts a rigorous certification process for every new airplane that ensures it meets the highest levels of safety, and the FAA has certified commercial aircraft that use composite materials for decades,’’ the agency said yesterday in a statement. ‘‘In addition to the extensive certification requirements, the FAA’s robust safety oversight system is designed to detect and correct any issues that may emerge during actual flight.’’

The GAO’s review was requested by Representative Eddie Bernice Johnson of Texas, Representative Donna Edwards of Maryland and Representative Jerry Costello of Illinois, all Democrats.

They wrote a letter to FAA Administrator Randy Babbitt on Oct. 20, asking that he explain what ‘‘practical and proactive’’ steps are being taken to ensure ‘‘robust oversight’’ of the 787’s maintenance and repair.

Training Personnel

As the model enters service, the FAA will need to train more personnel to deal with composites and certify more repair centers to handle work on the new planes, the GAO report said. Boeing has orders for about 800 of the 787s from carriers around the world, making it the company’s fastest-selling new plane ever.

‘‘Composite-built aircraft present opportunities as well as unique and complex challenges, and we need to make sure the FAA is addressing all of these challenges appropriately,” Johnson said yesterday in a statement.

All Nippon Airways’s first Dreamliner already suffered some slight surface damage to the engine cowling when it hit a passenger boarding bridge earlier this month, Flightglobal reported Oct. 19. The plane resumed regular flight tests with the carrier in Japan after the company did some checks, the trade publication said.

MRO Europe: Airbus cautious about bonded structural repairs on A350

It was an old articel but still worth to read..... OEMs VS MRO in Composite Repairs...

Source : http://www.flightglobal.com/news/articles/mro-europe-airbus-cautious-about-bonded-structural-repairs-on-a350-377511/

By:   MICHAEL GUBISCH LONDON

05:51 10 Oct 2012 

Source: 

Airbus wants to concentrate structural repair development for critical composite parts on the A350 to bolted repairs, as it views alternative bonded repairs as "too big a step" on primary load-bearing structures for the time being.

Frédéric Gaible, A350 structures engineer in the airframer's customer services engineering and maintenance division, says there will be "limited scope" for bonded repairs on the largely composite twinjet, as regulations do not allow for them "at this stage".

The focus will remain on repairs with bolt-on reinforcements, because the development of bonded repairs for critical parts in the outer fuselage and wing area, where in-service damage is likely to occur, would be "too big a step", he says.

Gaible made the comments during a discussion at the MRO Europe conference about the changing relationship between manufacturers and maintenance providers in regard to composite repairs.

Airbus views itself as the main source for structural repair development on its aircraft, while operators and MRO providers will implement the respective approved processes.

But MRO companies are calling for greater sharing of technical data to be able to develop their own repairs. James Kornberg, general manager for customer support, products and business development at Air France Industries' aerostructures unit, says it frequently discovers damage on aircraft "which the OEMs didn't know about".

He believes operational experience with the aircraft gives MRO providers an advantage over the airframers. While repairs on new-generation aircraft are becoming more difficult, competition between OEMs and MRO providers must continue, he says.

Arne Lewis, associate technical fellow for Boeing's 787 service engineering division, denies MRO providers are under threat from the OEMs. However, he warns that intellectual property will not be as freely available for new aircraft as on legacy models.