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HexMC® is a combina0on of a new material form and associated string of innova0ve technologies to make structural and complex shaped parts that that could not be produced economically with exis0ng high performance materials and processes. HexMC® bridges the cost/performance gap between sheet molding compound widely used in automo0ve (inexpensive but low performance) and con0nuous fiber prepreg (high performance but expensive). The aerospace version of HexMC® starts with a very well characterized (AS4/8552) aerospace grade unidirec0onal (UD) prepreg that is slit and cut into 50mm long x 8mm wide “chips”. The chips are then used to form a transverse isotropic mat (same proper0es in any direc0on within the plan of the material). The mat created is easily preformed and is equivalent in thickness to a quasi-‐isotropic (QI) laminate made of 8 UD plies, therefore greatly reducing labor. The HexMC® material form and associated processing techniques preserve the fiber orienta0on (and fiber volume) while molding the parts by “flowing” (moving) the chips slightly under pressure and temperature. The low flow of the HexMC® chips also allows the preforms to fill the mold boundaries producing “net shape” parts and elimina0ng expensive trimming required with other molding processes. Parts are in the press for about 20minutes, much shorter 0me than tradi0onal aerospace composite materials and processes. Delamina0on or other issues associated with tradi0onal laminar composite construc0on do not exist with HexMC® since HexMC® does not have a (inter-‐laminar) path to ini0ate and propagate damage easily like standard composites. This lack of well defined inter-‐laminar path in HexMC® results in very high resistance to damage and failure propaga0on in HexMC®. HexMC® is insensi0ve to holes, damage and defects (no stress concentra0on), and is extremely fa0gue resistant. HexMC® can also be machined without any effect on proper0es. In addi0on to the material itself, Hexcel also developed a number of technologies including mold design, molding processes to preserve the mat proper0es during molding. Material design allowables, structural analysis methods and non-‐destruc0ve analysis techniques were also developed. HexMC® is the first discon0nuous fiber composite to be used for aerospace primary structure applica0ons, displacing forged and/or machined aluminum, 0tanium and stainless steel parts.
HexMC® Molded Carbon Fiber/Epoxy Composite Parts
As new genera<on commercial aircra> and jet engines increasingly use carbon fiber composites for large flight cri<cal structures, a number of smaller complex geometry parts are required to connect these structures together. In the past these connector parts have been machined, cast or forged from aluminium, <tanium or steel. However, Aluminium parts are sensi<ve to fa<gue and corrosion and require frequent inspec<on and maintenance. Steel is heavy and sensi<ve to corrosion while Titanium adds significant weight and cost. HexMC® enables complex shapes to be manufactured in cost-‐effec<ve series produc<on while providing weight savings that are comparable to those tradi<onally achieved with aerospace carbon/epoxy prepregs. The resul<ng weight-‐savings reduce fuel consump<on and increase aircra> payload.
HexMC® has now become baseline for a large number of primary structures on the new genera0on of commercial airplanes, enabling complex shapes to be manufactured in series produc0on while providing weight savings that are comparable to those achieved with aerospace carbon/epoxy prepregs.
Boeing 787
Bruno Boursier, Hexcel R&T Manager and HexMC® Business Development Manager, Hexcel Corpora0on www.hexcel.com
HexMC® is used to great effect on the Boeing 787 Dreamliner, the first of which was delivered to ANA in Japan on September 26th 2011. HexMC® offers low density, with good strength and s0ffness proper0es, enabling complex shapes that would previously have had to be machined or forged from metal to be manufactured in composites in cost-‐effec0ve series produc0on. HexMC® parts provide weight savings that are comparable to those achieved with aerospace carbon/epoxy prepregs. Hundreds of HexMC® parts have been cer0fied for the 787 Dreamliner including Window Frames, Brackets, Fibngs, Gussets, Clips/Cleats, Intercostals and Pans. The HexMC® window frame has a significant impact on two key characteris0cs of the Dreamliner. The new low density, high strength composite frame results in almost a 50 percent weight saving over a tradi0onal aluminum frame. In addi0on, the frame offers superior damage tolerance.
New components to benefit from HexMC® are the Outlet Guide Vanes for the GE-‐Honda HF120 turbofan. The concept design of the OGV was developed by Honda and the manufacturing of them was jointly developed by GE Honda and Hexcel successfully. Each engine has 42 OGVs, which are great candidates to benefit from HexMC® technology while providing weight savings that are comparable to -‐ or beher than – those achieved with other aerospace carbon/epoxy solu0ons. The GE-‐Honda HF120 turbofan has a robust, simplified design to deliver greater payload, longer range and outstanding durability for business jets. The use of HexMC® contributes to the weight reduc0ons which, together with an innova0ve 3D aerodynamic design, provide enhanced efficiency and op0mize operability.
Hundreds of HexMC parts are qualified for the Boeing 787
Structural analysis of HexMC part
Fa;gue tes;ng of an OGV
Structural analysis of HexMC part
www.JECcomposites.com