Harnessing nature’s power Hexcel’s composite materials, processes and solutions for wind turbine blades

Harnessing nature’s power Hexcel is a leading global supplier of advanced composite materials to the wind energy market and has supplied more than 100 million square metres of composites to wind turbine blade manufacturers over the last 25 years. Our composite technologies have enabled blade lengths to increase to over 80 metres, supporting the growth of wind power around the world. We work closely with our customers to develop products and processes that are tailored to their specific requirements. This approach has enabled us to develop technologies such as: • repreg materials and process solutions...

Empowering technology Hexcel has developed a broad range of products and solutions benefiting from synergies with other cutting edge technology markets for composites including aerospace, space and defense. During the rapid growth of the wind energy market Hexcel has been at the forefront of developments supporting expansion by supplying technology solutions rather than just materials. To support the wind energy market Hexcel has dedicated manufacturing facilities in Asia, Europe and the USA.

A wind blade is a component for a machine designed to direct and concentrate energy from the air into a wire that connects the turbine generator to an electrical grid. The cost of such energy depends on advanced and cost-effective solutions to manufacture very large composite structures like wind blades. Prepreg is a glass or carbon fibre reinforcement that is impregnated with a resin (e.g. epoxy). Prepreg is supplied in roll form and cured by applying heat and pressure to produce high quality laminates with superior stiffness and strength - at low weights. Prepreg is an ideal economical technology...

Benefits of HexPly® M9-family prepregs: • optimised structural design • consistent fibre volume ratio • lower and consistent blade weight • pure UD materials with optimised performance/ cost ratio • high strength and fatigue properties • short total processing and cure cycle • clean working environment • low exothermic properties -enabling curing and co-curing of multi-ply laminates, e.g. carbon with glass • minimise stresses caused by differences in thermal expansion

A wind blade is a structural beam that throughout its operating life is subjected to considerable lift forces on its aerodynamic profile. Stiffening of the blade is therefore essential to resist bending. Sometimes two strips of reinforcing materials are used to provide local stiffening - one on the upwind face and one on the downwind face. However, to provide the essential shear strength these two strips need to be structurally joined by a construction called a shear web. There are different ways of designing a spar/shear web - either as a girder-structure connected by one or two shear-webs or...

The shell provides the aerodynamic shape of the blade and plays a role in stiffening and strengthening the spar, as the fibre orientation in the construction helps to resist torsion. Blade shells are usually quite thin as the requirements for strength in a shell structure are relatively low. However, to prevent large flat laminate areas from flexing - which could affect the aerodynamic shape and lead to buckling - certain areas are designed as a “sandwich” construction with laminated skins and a core (e.g. low density rigid foam or balsa wood). As blade shells provide the outer surface of the...

The blade root is usually circular in cross section to connect to the pitch bearing in the hub. The wind blades are fixed to the hub via a bolted connection that allows them to be removed. Most blade roots consist of a thick solid laminate with studs or T-bolts either screwed or bonded in. The girder structure (or box section) of the load carrying spar must be joined to the cylindrical laminate at the root. Normally this is done by incorporating a smooth curved transition area. Care must be taken during the curing of the composite structure as the high thickness in the laminate sections could...

Polyspeed® pre-cured glass/ carbon/epoxy laminates are used in conjunction with prepreg in a vacuum bag lay-up to improve the quality and optimise the structure of cured stacks. Polyspeed® pre-cured laminates are available in woven or unidirectional constructions fully supporting the mechanical performance of vacuum bag cured structures. As the materials are already cured when introduced in the lay-up the final exotherm upon curing can be reduced, additionally buckling, waviness of long lay-ups can be avoided completely thus providing optimised fibre orientation in large scale unidirectional...

HexPly® SuperFIT™ is a range of glass and carbon fibre reinforcements that have been partially impregnated with epoxy resin. SuperFIT™ is processed by applying heat and vacuum, which activates the resin, enabling it to flow and infuse the reinforcement. SuperFIT™ provides a quick and cost-effective way of producing large, thick laminates minimising porosity. HexPly® SuperCap™ is a range of heavy UD epoxy prepregs in glass and carbon fibre, with 32% resin content, ideal for thick load-carrying parts in wind blades. HexPly® SuperCap™ allows the advantages of prepreg and infusion technology to be...

Hexcel formulates a range of Modipur® Polyurethane (PU) core foams for wind energy applications and has access to a wealth of history and experience in PU technology built up over 30 years. PU foams are recommended for nacelle, shell and mould applications. Hexcel offers a wide range of industrial non-metallic Honeycombs (HexWeb® HRH78 and A10) in a variety of cell configurations and densities to support wind energy applications. Hexcel produces a range of HexForce® biaxial and triaxial reinforcements in glass and carbon fibre that are ideally suited for wind blade manufacturing. HexForce® Fabrics...