The rise of composites

Materials World magazine
10 May 2019

British Composites Society Board members Professor Steve Eichhorn, Paul Shakspeare and Chair Dan Kells, discuss the rapid and relentless success of composites across UK industries.

The past 150 years of human endeavour has been rapid. This period has seen the invention of what could be considered the first car by Karl Benz in 1885, and the very first flight of a fixed wing, heavier than air, plane by the Wright Brothers on 17 December 1903. Since these two epoch-defining inventions there has been a rapid development of technology, enabling virtually every citizen access to transportation on land and air, which has led to connectivity to our planet. Who could imagine a world without these two inventions?

Yet we now face the very real challenges of climate change, and the realisation that the liquid fuel that has, for the most part, powered these transformative technologies, is very much a finite resource. Alternative sources of energy, such as wind and tidal, have also led to the rapid development of offshore and in-land turbine technologies. These would not have been possible without the rise in aerospace technology. All of these advances have only been made possible through increased use of lightweight composite materials.

Composite materials have their foundations in ancient times. People have been using wood, nature’s natural composite, for many millennia. The structure of wood offers a natural form of a composite, wherein cellulose fibres reinforce a resin-like material (lignin). So good is wood as an engineering material that the very first planes were constructed from it.

Driven by our desire for higher structural performance, greater temperature and environmental resistance, we moved towards lightweight metals as the materials of choice. Led by the need to reduce the strength and stiffness to weight ratio of the structures, and also fuel efficiency, there has been an increasing need to incorporate composites into the structures of modern aircraft.

Grounding in composites

One early pioneer of composite technology in aircraft was Norman de Bruyne. In the UK in the 1930s, he developed a composite called Gordon Aerolite, which combined a liquid phenolic resin with flax fibres. He later went on to develop wood-based core laminate structures, and ways to bond these to metallic components. Boeing first used fibreglass in the construction of its passenger jets in the 1950s. If we track forward some years in this developmental timeline, we see that the replacement of more traditional metallic components has led to the 787 Dreamliner, which is 50% composite material.

Another major development in aerospace, led by the UK, was the British Experimental Rotor Programme (BERP), a joint venture between Westland Helicopters and the Royal Aircraft Establishment. This programme, which introduced new composite materials to the blade design, resulted in the setting of the absolute speed record for a helicopter – 400.87km/h (249.09mph) over distances of 15km and 25km. What made these feats of human endeavour possible was the very rapid rise in the use of high-performance carbon fibres.

Carbon fibres can trace their development right back to Joseph Swan. In 1860, he produced carbon fibres made from heating rayon (regenerated cellulose fibres typically used for clothing) to make light bulb filaments. These resistive heating elements were later used by Thomas Edison for his light bulb company. It wasn’t until the 1950s that Union Carbide developed structurally stiff and strong carbon fibres from regenerated cellulose, by first oxidising and stabilising the filaments, and then fully graphitising their structure. They made such leaps and bounds in their technology that they were able to patent and manufacture rocket nozzle cone composite structures in the 1960s.

The UK, however, really pioneered the production of carbon fibres. In the 1960s, Watt, Phillips and Johnson at the Royal Aircraft Establishment developed a process for converting an oil-based polymer (polyacrylonitrile) into a high-performance fibre. This was patented by the UK’s Ministry of Defence, and licenced to Rolls-Royce.

The perhaps too rapid a development of the technology into composite fan blades in the 1970s, and their subsequent failure under testing, led to
the break-up of the company. This is a salutary tale in the UK’s composites history, but shows how visionary the industry was back then to have seen the opportunities that are only now being realised. Composite fan blades are making a comeback in the very latest jet engine technologies being developed by the modern Rolls-Royce company, again drawing on UK expertise in this area.

Automotive composites

Composite materials in cars have roots in the incorporation of plant fibres into the body of a soy-bean resin-based composite by Henry Ford in 1941. His car weighed one third less than its metallic counterpart. Much later, the Trabant car in East Germany also had a natural fibre composite body that made it very lightweight, cheap, and fuel-efficient.

Only recently though have carbon fibres been making in-roads into car monocoque structures, early adopters again being UK manufacturers including McLaren and Jaguar in the 1990s. These early carbon-fibre car bodies were mainly reserved for the higher end market of super and hyper-cars, although more recently the i3 BMW range adopted the technology. Weight saving, and therefore fuel efficiencies, is a big driver in the adoption of carbon fibres in the family cars of the future. But, limits to production speed of the composites, and the supply chains of cheap carbon fibres not necessarily meeting the specifications required for aerospace, are currently roadblocks to their more widespread use.

The development of carbon fibre car bodies in the UK should also be linked to the increasing use of advanced batteries to power electric vehicles. A lighter body for an electrically powered car will extend its range, and modern developments in the UK to make composites that also store the energy (structural capacitors) have the potential to revolutionise the sector.

Blowing in the wind

As far back as the year 200, wind-powered water pumps were being used in China, Persia and the Middle East. The blades used were woven reeds. Later, wood was used for the blades of windmills, which were employed to grind corn, pump water and cut wood in saw mills. Wood-based wind turbines are still in use today, but the most modern development in this technology has been replacing metallic blades with composites.

Scottish Engineer Professor James Blyth is considered as  the first person to develop an energy-generating wind turbine in 1887. He aimed to not only power the lights in his house, but also the surrounding ones, but his plan was turned down after it was deemed ‘the Devil’s work’.

The Danish were pioneering in the development of wind power, and Poul la Cour had the vision to turn his own invention into a prototype that was eventually rolled out, at the turn of the 19th Century, to thousands of wind generators supplying considerable amounts of electricity. The USA was also an early adopter of wind technology, developing the very first windfarms in the 1970s. This state-sponsored programme was driven by a shortage of oil – at the time due to the OPEC oil crisis – and concerns over the environmental impacts of other forms of energy production.

According to RenewableUK, recent government information indicates there are around 9,685 wind turbines in the UK, and the International Renewable Energy Agency Renewable Capacity Report 2019 states that these have a combined operational capacity of 21,736MW. This equates to a reduction of 25,828,221 tonnes of CO2 per annum. The UK is presently ranked the fifth largest producer of wind power in the world. Although early wind turbine blades were produced from wood and then metals, modern construction typically uses composites – more than 90% carbon fibre composite at present, but the trend towards larger rotors is making weight and stiffness limiting factors, necessitating greater use of carbon fibre-based composites. Advanced composites, and the possibility that they could add extra functionality, such as shape adaptation, are an enabler for lighter, smarter blades and cheaper, more abundant energy.

Better buildings

There are also nascent areas of growth for the use of composites, such as in the construction industry. There were some very early UK-driven adoptions of glass fibre reinforced plastics in the 1960s and 1970s, including an umbrella structural form for Dubai International Airport, Mondial House at Blackfriars in London, and the American Express building in Brighton.

The major driver for using composites in the construction sector is the ability for them to be modular, lightweight for transportation, and durable. This is hugely beneficial for composite bridge constructions for example, although their benefits go beyond convenience. Damage caused by flooding and severe weather in the UK has led to the need for more rapid bridge repair systems. For instance, in Cumbria alone, some 29 bridges collapsed in the flooding in 2009. Composite bridges could make a significant difference by alleviating problems with national infrastructure in the short and long terms following the failure of more traditional materials.

The first composite bridge for highway vehicles was constructed in Clitheroe, Lancashire, in 2008. Spanning 10m and weighing just 20 tonnes, it was the first of six Network Rail trials into railway bridges and composite platforms on its system.

More recently, a modern composite bridge was demonstrated in 2017, when engineer Arup and construction firm Mabey created the first modular glass fibre, reinforced polymer structure that was pre-built for assembly at Oxford, UK. This pre-engineered technique using composite materials enabled the production of a lightweight and high-performance alternative to traditionally constructed bridges.

Driving change

Growth in the use of composite materials has been very rapid. As a nation, the UK has shown it can adopt and develop technologies at an early stage. To continue to do this though will require a technically trained workforce. The threats of climate change and the need to provide power and transport in the UK, and internationally, mean that increasing use of composites materials and structures is going to be central to the country’s prosperity. The UK Composites Leadership Forum (CLF) has forecast the opportunity for the composites industry to deliver a six-fold increase by 2030. This huge increase will be seen in the sectors mentioned – aerospace, automotive, renewable energy and construction – but also in others such as marine, defence, and oil and gas.

There is a very strong threat that the UK will not be able to provide the highly skilled workforce to achieve these targets, which stems from the overall engineering workforce skills gap today. A range of predictions put this shortfall at some 124,000 engineers and technicians annually with core engineering skills. An additional 79,000 will be needed with related skills to complement this core set. Given the number of engineers produced in the UK on an annual basis, this results in an estimated annual shortfall of at least 83,000 engineers – up to 110,000 across core and related roles.

This shortfall will almost certainly be felt within the composites industry, which currently employs around 23,000 people. Sales targets for the UK’s composites industry are set to grow from £2.3bln to £12.5bln, something that cannot be achieved without a trained workforce. Estimates on the higher skills required in the industry put shortfalls, by 2030, of about 500 doctoral students, masters of more than 1,200 and undergraduates of more than 5,000. Therefore, we need more courses in the UK to include study of composites. It is generally acknowledged that two thirds of the workforce of 2030 is already in work, hence some of these new entrants to the composites industry may well be reskilled adults.

The UK also needs inward investment of companies requiring this workforce to incentivise this growth. Simply leaving this to chance, or to the current status quo of higher education output could result in the investments going overseas, perhaps to the Far East where technical skills are growing at much more rapid rates. Opportunities like the apprenticeship levy and modular learning for an existing workforce should also form part of the training programme to deliver these technical engineers.

While the UK may have been central to the development of composites in the past, it cannot afford to lose out on the blossoming growth of the future. Enormous opportunities exist within IOM3, and the British Composites Society is supporting the professional development of composites engineers and technicians, starting at school level, to ensure the workforce grows to match the opportunities and the next generation is ready.

The future in composites is bright – but we need to seize the great opportunities that lie ahead.