Leading composites company Hexcel will be participating in the Paris Air Show at Le Bourget from 17th to 23rd June (Stand F80 in Hall 2B; Chalet 142, Row A). Display parts and promotions on the stand will demonstrate how the latest Hexcel innovations are enhancing new generation commercial aircraft, helicopters, engines and space applications.
Hexcel is proud to be the supplier of carbon fiber prepreg for the composite primary structures of the A350 XWB. The A350 XWB is the first Airbus with a structure that is more than 50% composites. A350 XWB structures made with HexPly® M21E prepreg systems and HexTow® IM carbon fiber from Hexcel include entire fuselage panels, keel beam, the entire wing covers, wing spars, center wing box and empennage. Hexcel is grateful to Airbus for the loan of an A350 XWB Stringer Run Out Demonstrator Panel to display at the air show – a part with skins and stringers both built in HexPly® M21E/IMA slit tape and UD tape.
Also at the air show Hexcel is promoting its newly launched breakthrough HiTape® advanced dry carbon fiber reinforcements. Developed with next generation aircraft primary structures and engine/nacelle components in mind, HiTape® combines the benefits of automated processing with the cost-effectiveness of Out of Autoclave infusion technologies. Parts produced with HiTape® and Hexcel’s HexFlow® infusion resins can be up to 30mm thick with a 58 to 60% Fiber Volume Content. The mechanical properties are therefore as high as those found in parts made with the latest generation primary structure prepregs.
HiTape® dry UD tape, made from Hexcel’s HexTow® carbon fiber, allows preforms to be manufactured in a fully automated lay-up process, targeting deposition rates above 50Kg/h. HiTape® eliminates the time-consuming processes of material splicing and polythene film removal. Customer evaluations have demonstrated that significant cost-savings are achievable with HiTape® and the associated vacuum infusion process.
Composites for Aircraft Engines
Hexcel’s composites are widely used to save weight and enhance performance in Aircraft engines to the extent that prepregs now typically account for half the volume of an entire nacelle structure.
Hexcel innovations for aircraft engines include HexMC® for which Hexcel was recently presented with a special award by Safran. The HexMC® bracket, developed for Snecma’s LEAP engine, represents a 75% weight reduction compared to its metal equivalent and pioneers a new way of using composite materials in aerospace. The brackets attach the FADEC (Full Authority Digital Engine Control) to the engine’s fan casing are critical as they are subjected to considerable vibration and thermal loads in service.
HexMC® consists of carbon fiber prepreg tape that is cut into 50 mm long x 8 mm wide strips and arranged randomly to give parts quasi-isotropy, with the same high mechanical strength in all directions. This is impossible to achieve with traditional methods of using prepreg, such as draping and weaving. HexMC® technology can be used to make high performance composite parts with complex shapes and also produce them in volume.
Another technology innovation that benefits aircraft engines is Hexcel’s HexPly® M91 prepreg that is used by CTAL – a Rolls-Royce/GKN Aerospace joint venture – to manufacture DOVE demonstrator fan blades for new generation lightweight turbofan engines. Hexcel supplies HexPly® M91 as slit tape which CTAL uses to lay-up the blade in an automated process that produces a complex aerodynamic shape, with a constantly changing thickness across the blade length. The result is as thin as a titanium fan blade - and lighter. HexPly® M91 provides outstanding performance, including very high toughness and high residual compression after impact (CAI). It gives improved tensile performance in combination with both Intermediate Modulus (IM) and High Strength (AS) carbon fibers. Good hot-wet properties up to 120°C (250°F) are also obtained. Good tack life and out-life provide flexibility during processing on the shop floor and low exothermic behaviour allows for simple cure cycles of thick monolithic structures.
Hexcel also innovates in jet engine noise reduction. A new treatment for Hexcel’s honeycomb core called Acousti-Cap® has been proven to quieten jet engine noise more effectively than any competing system. Acousti-Cap® is Hexcel’s broadband sound reducing honeycomb that enables engine designers to achieve superior acoustical performance without a structural weight penalty. Acousti-Cap® consists of a permeable cap material embedded into honeycomb cells to create an acoustic septum. Customers specify the flow resistance characteristics, overall core thickness, number of caps in a cell and insertion depth. The result is a product tuned to their acoustic requirements. Quieter engines bring a number of advantages including recurring cost-savings from lower landing fees at airports, increased fleet flexibility and improved cabin comfort.
Weaving Technology Innovations
Hexcel is a world leader in weaving technologies and PrimeTex® is a unique carbon fiber fabric in which the fibers are spread in both the warp and weft direction to provide a uniform weave and gap-free finish. The PrimeTex® spreading process increases the closure factor by 5-8% compared to conventional weaving processes (depending on the carbon tow and Fiber Areal Weight). PrimeTex® also allows high K tow fibers to be used without increasing the areal weight of the fabric or the closure factor between the warp and the weft, unlike traditional woven carbon fabrics.
PrimeTex® carbon fiber reinforcements are ideal for Aerospace laminates as the gap-free structure reduces porosity and requires less part finishing thereby reducing man hours. Very Low Weight PrimeTex® ( available at 98 gsm with HS3K carbon fiber or 160 gsm with IM12K fiber) can lower the mass of a composite structure, resulting in even greater weight savings than with standard composite reinforcements. Thanks to the combination of HexFlow® out of autoclave resin systems and PrimeTex fabrics, porosity is significantly reduced. In addition PrimeTex® gives excellent water tightness when used in honeycomb sandwich structures such as aircraft belly fairings or helicopter structures.