JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 44

FEATURE “Wind energy” The perfect mixture Rotor blades for wind-energy generators have now reached such a size that it is essential they be constructed from lightweight materials. However, even the slightest error in production can have a seriously detrimental effect on their function. Foremost in this respect have been concerns over control of the exact volume of resin used to impregnate the glass-reinforced plastic (GRP) matting that forms the blades, and over the ability to guarantee the mixing ratio, regardless of the actual flow rate of the mixed resin. These fears have now been laid to rest by the introduction of fully automated, purpose-designed metering and mixing systems. abrication of GRP rotor blades that can be more than 60 metres in length is a complex process. Achieving the specified lifetime requires a combination of the latest material technology, together with the most recent developments in automated metering and mixing systems(Figure 1). A common method of construction for rotor blades is to produce them in two halves, subsequently bonding them together and finally smoothing the outer surface of the joints with a gelcoat. Alternatively, the rotor blades can be cast in a single piece which, although technically more challenging, has the advantage of requiring neither the bonding nor the gelcoating processes. Equal infusion of the fibre mat Two alternative production techniques are available when using the two-half method. Either fibre mats impregnated with partially cured thermosetting resins – known as prepregs – can be used, or a two-component reactive epoxy resin can be infused into the fibre mats under vacuum, directly on-site. These processes may sound simple enough, but in reality, the sheer scale of the rotor blades demands a high degree of technical expertise. For example, the infusion process for a typical 50-metrelong blade will take upwards of six hours to dispense and use around 1,000 kg of resin, whilst 600 kg of resin is used on average for bonding the two halves together. The surface finish of the rotor blade is a direct consequence of the polyurethane mould, which can be reused many times. The rotor blade itself is hollow in section and consists of different layers, with a total wall thickness of just a few centimetres. The internal space is a complex composition of laminated parts, including balsa wood for reinforcement. A foil is used for support during the pressurised infusion process. Reproducible data In a comparison of dispensing systems currently available to undertake this process, capacity is very similar. The difference is in the flexibility and speed of the electronics that control the metering and mixing accuracy, and therefore are responsible for the reliability of the bonding. Naturally, every machine manufacturer asserts that the mixing ratio of their system is accurate during the entire production cycle, but this can now be precisely verified by means of a glass transition temperature test. This test defines at what temperature the material has the highest deformation and clearly identifies the point between elastic and brittle states. Consequently, the availability for on-site testing of potential dispensing machines is an important component of the end user’s choice in today’s competitive marketplace, where performance is no longer evaluated from data sheets, but from actual tests with the systems at their plant before the investment is made. This has been the experience of the Hilger u. Kern / Dopag Group with systems developed specifically for use in the manufacture of rotor blades, and as a Fig. 1: Wind energy generators JEC Composites Magazine / No40 May 2008

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #40 - May 2008

Cover
Edito
NEWS WORLDWIDE | Companies
Nippon Graphite Fiber increases production capacity
World’s largest ECR glass fibre plant
CPIC and Abahsain set up glass fibre joint venture
Airbus negotiations called off in Germany
A400M static testing
Agenda of events
Equipment: non destructive control
BUSINESS
Market survey: India
Trends | Two major sustainable development challenges: raw materials and energy
Niche market | Taking up the rapid manufacturing challenge
Human capital |Choosing the right opportunity
FEATURE | Wind energy : Market update
History : Not just another windmill story
Process : An experimental vertical-axis wind turbine system
Composite manufacturing process for wind energy
Materials technology for the wind energy market
Equipment : The perfect mixture
USERS’ PLATFORM
Composites in the world : Bamboo helmet
Very exclusive business cards
World’s First Integrated Wind Turbines
Solar energy and hydrogen powered plane
Successful partners : Art nesting in a composite bower
Applications : A Hybrid composite carbody for korean tilting train
KNOW-HOW : Environment
Coupling agent : Composite stone
Process
Bonding : INDAR
Special Asia
News
Application
Products from exhibitors
Participating companies
Singapore today
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Cover
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 2
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Edito
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 4
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 5
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 6
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 7
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - CPIC and Abahsain set up glass fibre joint venture
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - A400M static testing
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Agenda of events
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 11
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Equipment: non destructive control
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - BUSINESS
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Market survey: India
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 15
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 16
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 17
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Trends | Two major sustainable development challenges: raw materials and energy
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 19
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 20
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 21
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Niche market | Taking up the rapid manufacturing challenge
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 23
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Human capital |Choosing the right opportunity
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 25
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - FEATURE | Wind energy : Market update
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 27
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 28
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - History : Not just another windmill story
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 30
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Process : An experimental vertical-axis wind turbine system
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 32
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 33
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 34
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 35
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 36
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 37
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Composite manufacturing process for wind energy
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 39
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 40
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Materials technology for the wind energy market
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 42
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 43
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Equipment : The perfect mixture
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 45
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 46
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - USERS’ PLATFORM
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Very exclusive business cards
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Solar energy and hydrogen powered plane
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Successful partners : Art nesting in a composite bower
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 51
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Applications : A Hybrid composite carbody for korean tilting train
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 53
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 54
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - KNOW-HOW : Environment
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 56
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 57
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 58
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 59
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Coupling agent : Composite stone
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 61
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Process
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 63
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 64
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Bonding : INDAR
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 66
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 67
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - 68
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Special Asia
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - News
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - III
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Application
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Products from exhibitors
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Participating companies
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - VII
JEC COMPOSITES MAGAZINE - Issue #40 - May 2008 - Singapore today
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