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Cleaner flying with lighter materials

The transport world is desperate for lighter materials

The transport world is the single biggest driving force in the search for new structural materials and material production techniques, says Prof. Dr. Ir. Remko Akkerman, professor in Production Technology and Scientific Director of the Thermoplastic Composites Research Centre (TPRC.nl). Akkerman works together with a team of 40 people at the TPRC on a type of material that is gaining importance in industry: composites. ‘A composite is a composition of different materials with the aim of combining all the best properties,’ explains Akkerman. ‘The bricks made from mud and straw in olden days are an example of this. Nowadays, when we think of composites, we think fibre-reinforced plastics. Carbon fibres are often used because they are light, strong and heat- and chemical-resistant. Combined with plastic, they provide a robust, form-retaining and lightweight material.’

The Boeing 787 Dreamliner, the first of its kind

It’s no wonder that aircraft manufacturers are increasingly exchanging metals such as aluminium for composites. For the newest generation of Boeing and Airbus aircrafts, the proportion of composites is already around 50%, according to Akkerman. ‘Right now at the TPRC the main focus is on smaller aircraft parts, an area in which we are already making a big difference. But of course the impact on fuel consumption and eco-footprints will be far greater if complete hulls or wing parts are made of composites. More advances have been made in this area in military aeronautics. When it comes to passenger planes, the current Boeing 787 Dreamliner is one of the first to be built with large composite parts.’

From thermoset to thermoplastic

Most of the composites currently being used are thermoset composites. The next step is to apply thermoplastic composites at industrial level. These are more malleable after heating and also easier to recycle. Akkerman: ‘Thermoset materials are comparable to a biscuit: once it has been shaped and heated, it has to be used as it is. Thermoplastics are more versatile. They can be re-heated and re-shaped, or pre-formed parts can be welded together. On top of this, it takes very little time to heat and cool them, which is important for mass production. For players like Boeing and Airbus these are very interesting materials. This is why alongside the growing popularity of thermoset composites we are now seeing explosive growth in thermoplastic applications. These materials are also very interesting for the energy sector, for example, in wind turbines, and for the automotive industry – especially if you consider the fact that cars increasingly run on batteries: lighter materials compensate for those heavy batteries.’

A different material for each component

Worldwide, countless researchers and companies are developing composite materials. This includes renewable varieties, such as bio-composites, which contain plastics made from plant-based fibres instead of petroleum, for example. ‘The rise of composites is comparable to the breakthrough of plastics in the 1920s and 1930s,’ says Akkerman. ‘Plastic took off in a big way, especially in consumer products. This was partly due to the unrivalled production speeds that could be achieved with it. With today’s new materials we’re also reaching new levels. The phase of point solutions is over and we’re now working on generic design methods and optimized construction, choosing specific materials for each individual component according to the requirements associated with that one component. It is impossible to say where this will end.’

TPRC, ‘the perfect platform’

Akkerman emphasizes the crucial role of fundamental scientific research when it comes to developing new materials. ‘Aircraft and automotive parts have to meet the highest safety and production requirements. In order to guarantee this, we have to improve our ability to understand and predict the material’s behaviour during production. Progress in this area will increase the production speed, applicability and reliability of thermoplastics. The TPRC is the perfect platform for this, as it does not just engage scientists, but brings the whole production chain together: material suppliers, software specialists, machine manufacturers, Original Equipment Manufacturers – everyone is on board, and as a result, we can quickly identify the missing link at each new stage. As far as I know, the TPRC is the only institute in the world that works with thermoplastics at this level.’

PROF. DR. IR. REMKO AKKERMAN
prof.dr.ir. R. Akkerman (Remko)
Professor of Production Technology, University of Twente | Scientific Director of Thermoplastic Composites Research Centre (TPRC), Enschede

‘I jumped into thermoplastic composites in the 90s, because I saw them as a very promising material for the future. One of the nice things about working with composites is that you can touch them. It is a very tangible field – and yet also surprisingly complex. Again and again you come across phenomena that awaken your curiosity and raise questions, like: What is the cause of this? How does this work? Can we predict this? And the great thing about research is that everything seems simple in hindsight. With every new discovery you think: why didn’t we see that earlier?’