COMPOSITES EUROPE Blog

COMPOSITES EUROPE Blog interviewed Stephan Knappe – International Sales and Applications Manager at NETZSCH-Gerätebau GmbH. The company is a new exhibitor at COMPOSITES EUROPE show in September!

Q: Question

SK:  Stephan Knappe

Q: Please introduce yourself – who are you, what are your responsibilities at NETZSCH-Gerätebau GmbH?

SK: Chemical engineer, International Sales and Applications Manager, dedicated to polymer and composite applications. Currently also responsible for sales in Southern Europe.

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Done and dusted. The German government’s decision to withdraw from nuclear energy has also paved the way for the development of renewable forms of energy. The proportion of electricity generation from renewable sources is expected to rise to at least 80 percent by 2050. Wind energy is planned to play a major role in this. Last year the sector contributed 7.9 percent to the total amount of electricity generated in Germany.

The energy policy of the German government includes giving greater support to offshore wind farms. The remuneration for this power is to be raised to 15 cents per kilowatt hour. Operators of onshore wind turbines will continue to receive up to 10.2 cents per kilowatt hour. 0.5 cents are paid for power from new wind parks if the old equipment went online before 2002. The new turbine should also deliver twice the amount of power than the old one.

Example of how the crystal structure could be used in the rotor blade of a wind turbine. (Photo: Wüstefeld)

These factors therefore represent healthy prospects for the future of the wind power sector. The manufacturers of fibre-reinforced composites are also expecting to benefit from this development – because modern wind turbines are inconceivable without glass and carbon fibre-reinforced plastics. The organisers of the international Composites Europe (CE) exhibition, to be held from 27 to 29 September 2011 in Stuttgart, recognised this early on and are giving the industry the platform it deserves. Well-known producers and processors of fibre composites for the wind energy sector and the relevant machine producers and suppliers get together each year at the event.

But it is not only the presence of the big names which makes a visit to the exhibition so worthwhile. Jens-Hagen Wüstefeld from Starnberg, for instance, has developed a crystalline structure as a lightweight construction element. It yields an 85 percent reduction in weight, lower manufacturing costs, outstanding rigidity and design flexibility in comparison to a solid material. Starting out with a geometric concept, he made a three dimensional lattice from triangles, similar to a crystal structure. Any forces applied to such a symmetrical grid are distributed optimally to adjacent surfaces and edges.

These lightweight elements can be manufactured to any scale, from any materials and in any form – including those appropriate for wind turbines. The resulting reduced weight of the tower would allow the foundation to be simplified. And the lower weight of the rotor would result in lower bearing loads and therefore reduced wear and greater efficiency in the entire turbine. The reduced amounts of materials required would also reduce production costs. Individual segments can easily be joined together, simplifying both transportation and erection.

When the new Airbus A350 XWB (XWB stands for eXtra Wide Body) takes off on its maiden flight in two years time, this will also represent a milestone for the composites industry. 50% of the fuselage of the wide-bodied aircraft, which is being developed as a competitor to the Boeing 787, is made of composite materials. Last summer, Airbus purchased Read Full Post

The significance of wind energy is increasing throughout Europe.

A study carried out by the European Wind Energy Association (EWEA) shows that capacity increased by just under 20% to almost 65,000 megawatts in 2008. The possibility for growth is Read Full Post

To ensure their suitability when used in wind energy systems, the epoxy resin adhesives used must be suitably certified by Germanischer Lloyd (GL). This is because rotor blades must withstand extreme stresses. The larger the unit, the higher the demands on the fatigue strength of the rotor blades manufactured from composites. In the near future, experts predict 10 megawatt systems with 80 metre long wind vanes.

The enormous rotor blades consist of two half shells, that are produced in suitable moulds from cross-linked hard foams and inserted balsa woods, which are subsequently stuck together. The balsa wood is cultivated in plantations in Ecuador and is harvested after six years. From a one metre long tree trunk, rectangular timber sections are cut and stuck together to make 1.22 metre long and five centimetre wide ashlars. These blocks are then cut into boards against the grain and finely sprayed with a resin solution to protect them against moisture.

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Whether recreational craft, aircraft components such as the fuselage and wing shells, railway trucks, surfboards, rotor blades for wind power plants or superstructures of commercial vehicles or caravans, without sandwich structures the most important applications of composites would be inconceivable. A sandwich structure is a type of lightweight construction, in which the components consist of force absorbing covering layers that are kept at a distance by a relatively soft, normally light, core material.

The sandwich structure is a production process for semi-finished goods, in which several layers with diverse characteristics are embedded in a material. Almost always, this involves the use of diverse composites, since despite being of a low weight these components are very rigid. They are computed according to the linear sandwich theory. The core material preferably consists of paper honeycombs, foam materials or balsa wood. It transmits arising shear loads and supports the covering layers. The thermally insulating and acoustic insulating properties of the very light core materials are also frequently utilized.

Optiplan GmbH from Oelsnitz is one of the leading manufacturers of glass fibre reinforced plastics as panels and reels under the Polydet brand. Apart from the main application as high-grade wall coverings on vehicle superstuctures, GRP products are also used in the technical, industrial and construction sectors. The company will present its latest products at the Composites Europe trade fair, which takes place in Stuttgart from 27 to 29 October 2009.

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The wind energy industry is one of the most important customers for composites; at the same time the greatest challenges are made here on the load-bearing capability of the fibre reinforced plastics. Consequently, not only the right raw materials but also their specific blend is a major precondition for use in wind energy.

The industrial production of the enormous blades would be impossible to achieve without the use of technical plastics. Production of the models or the moulds for constructing the rotor shells or the rotor blades as such would be impossible. Even the adhesion of the upper and lower shell would be virtually impossible to achieve.

Two-component metering and mixing systems are required so that the right mixture of epoxy and polyurethane resins as well as modelling and adhesive pastes can be used. A reputable manufacturer of this processing technique is Tartler GmbH from Lützelbach, which will demonstrate its competencies at the COMPOSITES EUROPE trade fair, which will take place from 27 to 29 October 2009 in Stuttgart.

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Epoxy resins are the elixir for numerous composite applications. They consist of polymers, which together with suitable hardeners produce a duroplastic plastic of high strength and chemical stability. When epoxy resin and hardener are mixed, after a specific time, curing of the originally viscose mixture takes place. Depending on the formulation and temperature, this time span can take a few minutes or may last several hours. In some cases, the curing time may also take several months.

The Krempel-Group, from Vaihingen, offers with the BD system, prepregs that are based on modified epoxy resins with high impact resistance and excellent dynamic properties. These can be processed into high strength structural components with all standard processes. The curing range is between 85 and 140 degrees Celsius, the maximum dimensional stability under heat is 125 degrees Celsius.

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