Analysis
Composites - Resized 2

Composite materials

Composite materials are the most important materials to be adapted for use in the aviation industry. Nick Rice reports on the growing demand for them in the aftermath of the global economic downturn.

The world’s airline fleet size is surely and steadily increasing, with record numbers of aircraft being ordered every year. Yet there is no denying that the economic turmoil triggered by the global downturn hit the aviation industry hard. The current increase in the world’s aircraft numbers is of course good news for the industry, but in a climate of unpredictable fuel prices, controlling costs has never been more vital. This translates into optimising every aspect of operational performance, and the gains in terms of weight, durability and maintenance in the use of composite materials is becoming crucial.

The most important benefits of composite materials are their strength and lightness. The more lightweight an aircraft is, the less fuel it will burn, and so reducing weight is paramount for aeronautical engineers.

Despite the recent financial hardship for airlines and related maintenance companies, the composites industry seems to have benefited, capitalising on the notion that where there is depression, there is opportunity. The demand for composites in the global aerospace sector is booming, fuelled by large commercial aircraft production and the increased build rates seen across the military, business jet and civil helicopter markets.

The aerospace industry uses a higher proportion of advanced composite materials in the construction of each new generation of aircraft. Back in the 1950s, when the most common composite of fiberglass was first used in the Boeing 707 passenger jet, composites accounted for two per cent of the structure. By contrast, composites on the 787 will account for 50 per cent of the aircraft’s structural weight and composites make up about 25 per cent of the total airframe on the Airbus A380.

National Institute for Aviation Research

With Boeing and Airbus both increasing the production rates of new aircraft such as the 787, A380 and A350, the demand for composite materials shows no sign of slowing down. This is confirmed by Paul Jonas, director of the Environmental Test Labs at Wichita State University’s National Institute for Aviation Research (NIAR). He says that despite the financial downturn, “We have actually seen an increase in our work in composites. It appears that our clients are preparing now to have an advantage when the industry rebounds.”

Wichita may evoke images of the railroads thanks to Glenn Campbell’s famous ode to the ‘Wichita Lineman’, but it is in the field of aviation, with composites and advanced materials research, development and production that the region truly excels. South Central Kansas is home to a rapidly developing industrial cluster of firms in the advanced composites sector and Wichita is the base of the world’s leading aviation manufacturing cluster. This connection to composite aircraft component design and fabrication stretches back over a quarter of a century to the development of the all-composite Beechcraft Starship, Raytheon Premier business jets, Boeing-Wichita’s development of composite nacelles and struts and Cessna’s development of proprietary composite technology.

NIAR was founded in 1985 and, as the largest aerospace research and development academic institution in the US, it accounts for over 70 per cent of Federal Aviation Administration (FAA) composite research spending. The FAA appointed NIAR as the lead institution of the Centre of Excellence in Composites and Advanced Materials (CECAM), which has been designated by NASA and the FAA to develop national standards for aircraft composites.

In reference to the recovery since the downturn, Jonas continues, “When the aviation industry was forced to downsize, many manufacturers lost significant intellectual capital and this will take some time to recover. However, NIAR has benefited because these organisations now come to us for specific tasks like material qualification. It seems that many organisations are now developing new products at the same time. One concern would be whether or not regulators will be able to keep up during certification phases.”

Jonas is distinctly optimistic about the composites industry and he identifies significant progress across the board. “Better analytical tools are allowing for improved optimisation and the resulting products are becoming more cost-effective. There is a tremendous amount of innovation in the industry with novel ways of processing and assembly.”

Whereas composite parts were originally only secondary components, we now see a composite use increase of up to 50 per cent, and more in specific cases. This also encompasses critical parts and the crucial area of composite parts repair — especially when these parts cannot be easily disassembled. Highlighting further improvements in the field Jonas concludes: “There is more focus on generating an overall cost-effective solution rather than solely focusing on weight. This means that the airframe designer must consider acquisition costs; cost to operate, maintain and inspect; and cost of weight and fuel burn. Additionally there have been advances in repair technology.”

Structural repairs

Composites are not only used as the essential building material of aircraft; they are also vital for conducting structural repairs. In a world where the phrase "time is money" has never been more true, and where every second of downtime counts in any air fleet, there is a growing demand for composites that can be applied in maintenance repairs without dismantling the parts of the aircraft, and is therefore a much faster fix.

A leader in this area is Sunaero. Based in France, the company was founded in 1992 and has built a solid reputation in niche markets which include composites, fuel leak detection and sealants. Working in the commercial sector and also for military operators, the company provides safe and effective structural repair solutions.

Sunaero’s major clients are maintenance, repair and overhaul providers (MROs), airlines and major aircraft manufacturers, including: Boeing; Airbus Industries; Air France; Lufthansa; TAP Portugal; and the French and Finnish Air Forces. The company dedicates 15 per cent of its turnover to research and development (R&D) and on average registers three new patents every year. This heavy investment in R&D now positions the company as a worldwide expert and pioneer in structural repair technologies and it dominates the market for developing solutions which optimise maintenance processes, reduce costs and improve safety.

Despite its reputation at the forefront of the composite and aircraft repair industry, Sunaero runs a smaller operation than many competitors and therefore deploys an out-of-the-box, creative approach in order to compete against rival scale economies. According to company VP Thierry Regond, “Our strategy is to be considered as the technological pioneer and leader in the highly attractive niche market of MRO of the future efficient fuel leaks detection, rapid structural repair, composites and faulty sealants rapid curing.”

Fabrice Parodi, sales and marketing director at Sunaero, echoes his VP’s positive and pioneering stance, saying, “The key reason for the success of Sunaero is that we bring added value for the users of our technology. Time and money savings are achieved with improved aircraft availability, with the same or better quality of repairs than comparable classical means - if existent - plus improvement in terms of health and safety for maintenance technicians.”

Three years ago Sunaero was tasked with the development of new equipment for in-depth drying of composites in situ. The French General Directorate for Defence Armaments and Investments selected the firm to create this composite curing (drying) device to quickly cure composite materials without the need for dismantling any parts. The resultant prototype is still being tested but it is due to come to market in the near future. 

One of the main challenges with composite materials is the interaction with other materials. This interface between the composite and a traditional material is crucial and when conducting repairs, the assurance of unchanged mechanical properties can be a real challenge. A new device developed by Sunaero promises to accomplish repairs on aircraft parts which were previously too thick for existent equipment to cure the composite.

Parodi describes the device and its use saying, “Sunaero has developed new equipment providing in-depth quick curing of composite materials. Portable and easy to set up, this equipment can cure the composite parts directly on the aircraft, without dismantling and without contact. Thanks to its specific design, flat surfaces and also round shapes can be cured within the same temperature parameters.”

The new equipment will incorporate a handheld device with a touch screen that will allow management to receive information in real-time. The operator can create and modify curing cycles and the traceability of the completed curing cycles can be recorded and printed. Sunaero says the equipment required fits inside two sturdy cases that can be safely and easily carried onboard commercial flights. It is another progressive step for the company and an achievement in the polymerisation of thick, flat and complex parts.

The difficulties the aviation industry has endured in recent years and in the immediate present continue to present positive business opportunities for companies like Sunaero. As Parodi explains: “The slow economy is affecting the operators and we offer them effective solutions to reduce maintenance costs and increase the availability of the aircraft. The manufacturers have more ramp-up issues and again, our solutions help them to save time. Only on the military side do we see a slowdown, but our technologies bring an easy way to increase efficiency and reduce costs.”

As to how the composites market will look in a decade’s time, it is hard to predict, as Parodi believes companies are already working at the outer limit of current capabilities. “It is difficult to assess how the market will be as probably a limit has been reached in term of percentage of composite materials. We do not see a possible increase except if high temperature materials can replace classical parts on engines,” he says.

Prepregs

A specialist in pre-impregnated (prepreg) fibre reinforcements or cloths that are used to manufacture composites, PRF Composite Materials is another leading supplier of high performance materials for the advanced composite industry that is consolidating and geared up for growth after the downturn.

Formed in 1982, PRF Composite Materials supplies a range of products and services in the industry, including prepregs (tooling and component), high performance reinforcements, epoxy resin systems, aerospace adhesives, release agents and composite tools. The last three years have seen substantial development as PRF’s business development manager, Crispin Jones, describes: “PRF is a flexible company committed to supplying the highest quality materials from rapid response warehouse facilities. We are investing in the economic downturn to position PRF to expand further in the future.”

This expansion includes a major installation of a new prepreg line. Representing the culmination of two years of substantial development and investment, PRF’s new prepreg line will complete the latest phase in the company’s recent development and will complement their existing range of composite materials. Manufacture will commence at PRF’s headquarters in Dorset, UK, by the end of May 2013. With a capacity of over one million linear metres at 1.5 metres wide, the new line will be suitable for large quantities and supplied with a service that rests upon extensive experience in fabric development and technically advanced products.

Extending their current prepreg capabilities, the new service will include both solvent dip and hot melt processes with a range of materials, including woven fabrics, UD prepregs, resin films and adhesive films. The extensive lab facilities will also be used by a team of dedicated technicians to provide R&D development and resin system formulation in-house; prepreg materials will be produced to a high level of accuracy, using the latest film weight scanning technology.

Managing director Robert Burnell comments: “In prepreg manufacturing over the last 25 years the focus has been on development in resin systems, but very few advances have been made in the development of the reinforcements. We believe that there is far more to be done by using the latest fabric technology in the manufacture of prepreg. This is central to our aims — the best prepreg can only be made from the best raw materials.”

For Jones, progress in the industry has occurred via incremental developments of resin and fibres and in processing. As ever, cost reduction will always play a role and he also points to recycling as an increasingly important focus. “Low cost carbon fibre imports from the Far East are driving down prices in Europe and recycling will start to become more of an issue as more carbon-fiber-reinforced polymers (CFRP) materials are used,” he says.

The future of the composite industry looks set for continued expansion, with mergers and acquisitions likely, long-term growth guaranteed and exciting new products and applications always on the horizon.

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