Tag Archives: OOA

Bombardier Learjet 85- OoA prepreg and infusion process

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Bombardier Learjet 85- OoA prepreg and infusion process

At the end of the year we have thought it would be interesting to review one of the most interesting discussions we have had in our activity on linkedin. It was at the Composites Group. The news that Bombardier was using dry fiber and Resin Transfer infusion on the Learjet 85 wing box started an enriching discussion about the technical difficulties and possibilities of resin infusion processes and out of autoclave curing.

Learjet-85-mockupLearjet 85

Bombardier Learjet – composite

“Bombardier unveils OoA composites process for Learjet. Wingskins and spars for the plane are manufactured in Belfast using an in-autoclave resin transfer infusion (RTI) process. The fuselage and autoclave are manufactured in Querétaro, Mexico, via an out-of-autoclave (OOA) prepreg process.”

“ It makes use of composites not only to reduce airframe weight and increase fuel economy, but also to significantly reduce the part count because composites have enabled Learjet to produce large, integrated structures.”- Composites World

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Liquid moulding manufacturing- not necessarily OoA

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We are used to hearing  about liquid moulding processes linking them with curing steps out of autoclave. However this is not always the case.

While the autoclave is one of the most expensive elements of the production process of big composite parts on the aeronautical sector, and therefore is highly interesting to develop processes that do not need it, this in not the only advantage of  liquid moulding.

Among the main advantages, we find the use of dry materials with long shelf life that lowers costs. Furthermore it facilitates working with non crimp fabrics, reinforcements that are making great advances in properties that allow a simplification of the lay up. By liquid moulding it is also easier to manufacture monolitic parts, integral constructions as a single piece, i.e. skins and stringers, avoiding fastening step.

ALAComposite wing

In this sense a very interesting  interview was published in the latest edition of  Aerospace Manufacturing .

They interviewed Mike Richardson, Bombardier Aerospace, Belfast´s vice president, engineering and business development .

He talks about the experience of Bombardier in the production of the  all composite wings of the C-Series. For this purpose the use a patented proprietary process named RTI (Resin Transfer Infusion). The process was created as an alternative to RTM which results in high quality parts but would need two expensive big dimension moulds.  The RTI consist in the infusion of very controlled amounts of resin into the dry fiber and an autoclave final curing step .

 AUTOCLAVEC-Series wing curing step

 

Collin Elliot explains that during the development of RTI they could state new advantages of the process that created very consistent parts reducing the gaps that should be filled with shim material, with the introduction of local “intensifiers” during cure, they were even able to completelly eliminate shim in certain areas.

They could also speed up the laying process, in his own words: “For the RTI process, we can use individual plies which are 2,5 to 3 times thicker than those used in traditional prepreg materials because the thickness of a pre-impregnated ply is limited in order to ensure the right resin saturation level. So we need many less individual plies of dry fabric to achieve the right strength and  stiffness, thereby significantly reducing the labour content and cycle time”

The next step is to develop an automated lay up process which could also improve the costs associated to very sofisticated ATL/AFP systems.

-Sampe Europe 2014: from aerospace OoA to automotive thermoplastics

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The title of the 35th International Technical Conference & Forum organized by SAMPE was “Low cost Composite Processing, from Aerospace OOA to Automotive Thermoplastic”. As the title indicates the main issues were the way to decrease the manufacturing cost in aerospace composites and the relation between thermoplastics and composites in automotive.

As it is known, it is very important to avoid the autoclave in order to reduce the composites manufacturing

  • reducing tooling cost for component development and low-rate production runs
  • adding capability for manufacturing of very large highly integrated composite components
  • reducing capital costs for autoclave and associated facilities
  • and removing autoclave bottleneck for production

Different methods for avoiding the autoclave were discussed along the conference, the experts presented different projects related to this subject, focused on the use of NCFs and resin infusion methods (summarized below).

Taking into account the unique challenge of increasing the presence of composites in new single aisle aircraft, current works are targeting at developing robust, fully automated processes for the realization of large scale structures. New functionalities are being added to existing materials, like e.g. enhancing conductivity for the improvement of lightning strike behavior.

On the other hand, thermoplastic materials are being optimized and, last but not least, new multi-functional composite materials are under development to broaden the range of composite applications. In addition, huge efforts are being undertaken to enable structural bonding for composite repair.

With respect to the automotive application, the use of carbon fiber reinforced thermoplastic was considered the next challenge. The laser assisted and induction processes in welding and heating with thermoplastics were the most important topics of discussion.

Related to the main subject of the DRY COMPOSITES blog, some projects have been outlined from the conference:

  • In terms of OoA manufacturing technologies by means of NCF and RTM, Airbus Military presented its BAHIA project, focused on alternative fan cowl doors configuration and manufacturing.  Within the project framework a new fan cowl door is designed and a RTM technology is used in order to manufacture the structure, by eliminating 2 autoclave curing cycles and joining grid and skin through a unique bonding line. This way, Airbus Military intends to obtain a more competitive and reliable product.

       Co-authors: Javier Gomez Vega, Maria Antonia River Orellana, Luis Rubio García

Airbus 340-642 fan colw door

Airbus 340-642 fan cowl door

  • Researches from Irish Centre for Composite Research, MSSI and University of Limerick presented a design of experiments study assisted in optimising the LRI manufacturing process (liquid resin infusion). According to them, LRI processes is challenging due to the difficulty in achieving full fibre wet-out, target fibre volume fraction and acceptable void content etc. In this study, flat composite panels were manufactured using aerospace grade Benzoxazine resins systems (one of which is targeted at high temperature applications) and aerospace grade carbon fibre NCF (non-crimp fabric with and without powder binder).

      Co-authors: Anthony Comer, Dipa Ray, Winifred Obange, Gearoid Lancy, Inga Rosca, Walter    Stanley

Double-omega stiffened skin manufactured by VIM using Benzoxazine B.

Double-omega stiffened skin manufactured by VIM using Benzoxazine B.

  • Other EADS, Eurocopter and University of Stuttgart researchers did also present a study, aimed at the fundamental material behavior of such unidirectional-braided structures, which are converted from carbon-fibers and thin thermoplastic auxiliary-yarns directly to the part geometry as UD-plies. The promising results emphasize the feasibility of using UD-braiding for structures with high stiffness as well improved damage resistance.

Co-authors: C. Metzner a, A. Gessler a, C. Weimer a, U. Beier b, P. Middendorf

UD-braiding – the machine, process and textile

UD-braiding – the machine, process and textile

 

-We go dry

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Dry Composites is an initiative by Danobat Composites to share the latest advancements in automation using dry composite material. This online community aims to connect companies, research centers, academics and experts interested in the use of dry composite material to develop structural parts in aerospace.

What do we mean by Dry Composites? There are two distinct methods of making composite structures. The first involves impregnating the fibres in a dedicated off-line machine to make a pre-impregnated material, called pre-preg. This is then transported to a factory that makes structures where it is laid up by machines or manually.

The second, more direct route is to take dry fibres, usually in some textile format and after assembly into a pre-form, infuse them with liquid resin. The infusion process is known by a number of trade names and acronyms such as RTM, VARTM etc.

The pre-preg route involves an extra process and hence cost, but it does result in structures with good consistent properties. Recently, the performance of structures made by infusing Dry Preforms has improved and is now claimed by some, to match that of more conventional pre-preg materials. Working with dry fibers, fabrics and textiles enables thicker layers to be used, saving time and labour costs, plus aiding in the creation of more complex, one-piece structures.

However whereas the pre-preg manufacturing industry is well served by automation with dedicated machine tools, the lay-up of dry fabrics has not received the same attention. Danobat Composites has pioneered the development of Automatic Tape Laying using woven and NCF fabrics. This has improved laminate quality, repeatability and reduced the cost of composite structures by significantly cutting manufacturing labour and material costs. Moreover, it is worth mentioning that the use of dry materials can give rise to out of autoclave curing processes acquiring required properties in primary structural aerospace parts.

Today, manufacturers face the challenge of doing more with less, the aerospace industry needs to adapt quickly to new material and process developments to remain competitive. In doing so, the ultimate goal of a disruptive automation technology is to introduce new processes that may deliver better high efficiencies and control at less cost. This requires broad support from an ecosystem of R&D, manufacturing, engineering teams and material developers.

Dry Composites is an open space for those interested in learning more about how automation using dry composite material can be applied to the aerospace industry. From sharing industry news, information, data and technical solutions about dry composite solutions to interviews and perspectives from expert sources. Our target audience includes decision makers, R&D engineers, global suppliers of advanced materials, software and automation companies.

If you are interested in learning more about advancements in the use of dry material in the aerospace industry, follow us on Twitter @drycomposites and join the LinkedIn Group Dry Composites.

Stay tuned for more!