High-Performance Composites

NOV 2014

High-Performance Composites is read by qualified composites industry professionals in the fields of continuous carbon fiber and other high-performance composites as well as the associated end-markets of aerospace, military, and automotive.

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N O V E M B E R 2 0 1 4 | 4 9 N O V E M B E R 2 0 1 4 | 4 9 80°C/176°F-cure epoxy system. The re- sult was B-staged and then wound onto reels specially designed for loading di- rectly onto NTPT's automated tape lay- ing (ATL) head. The ATL machine was custom designed and built by NTPT to layup up preforms using its super-thin prepreg materials according to custom- er-designated fber orientations and ply schedules. "The fnite element analysis (FEA) and laminate design was developed by the Solar Impulse engineering team," Rocher reports. NTPT, in fact, devel- oped its own software package for FEA and simulation, preform design and ATL monitoring. "That initial design was processed by Decision to create the ultimate design of specifc structural components and prepreg preforms for best handling and manufacturability." NTPT then made the ATL CNC manu- facturing fles from the design provided by Decision. The uni tapes were layed up by NTPT's ATL. The ATL head can be enclosed in plexiglas to allow temperature adjust- ment for the specifc resin prepreg chemistry, typically between 16°C and 23°C (61°F and 73°F). Further, the room that houses the ATL is maintained be- tween 18°C and 23°C (64°F and 73°F). depending on the resin type and tack requirements. Although the ATL is capable of pro- ducing large preforms — up to 3.4m by 12m (11 ft by 39 ft) — the Si2's central wing box, alone, is 27m/88.6 ft long. To accommodate the extra long layups, NTPT built a doorway with a fabric clo- sure in the end wall of the ATL room. The fabric could be lifted out of the way, permitting the NTPT team to set up a second layup table that accommodated the 27m length. "For long preforms, we lay down the material onto the 12m ATL table and then we shift what has been laid to the next table and we carry on the laying on the ATL table," Rocher explains. Preforms for the wing, which spans 72m/236 ft, were layed up in simi- lar fashion, but in three sections: One at 27m/88.6 ft long, and two others each 22.5m/73.8 ft long. For the Si2 preforms, tapes were placed in multiaxial orientations directly onto an epoxy flm (also an 80°C cure system). Because the exceptionally thin plies of material would make the Si2 pre- forms diffcult to handle, each fnished preform/epoxy flm was placed on sili- conized paper and covered by polyethyl- ene flm. Then each was vacuum bagged and compressed for debulking at about 0.8 bar. This was done to make the Si2 preforms easier for Decision's techni- cians to handle when they arrived at Decision for molding. The consolidated preforms, with protective paper and flm, were then rolled up for shipment to Decision. After layup, prepreg preforms are stored in a discrete room maintained Sun Up or Sun Down Renegadeʼs High Performance Materials Are Ready for the Mission Prepregs – Resins – Adhesives Polyimides Toughened Epoxies Bismaleimides Hybrid Systems Cyanate Esters High Temp Leaders www.RenegadeMaterials.com NTPT developed its own software package for fnite element analysis and simulation, preform design and ATL monitoring.

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