CompositesWorld

FEB 2016

CompositesWorld

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FEBRUARY 2016 52 CompositesWorld PLANT TOUR BASF high-performance materials are smart —and yes, beautiful. Our plastics and polyurethanes can be found in the innovative designs of some of the world's most popular automobiles. At BASF, we create chemistry for a better tomorrow. And a smarter ride. www.performance-materials.basf.us that lets beauty love brains. t h t l t We create chemistry moisture ingress than autoclave-cured systems. If an impact event causes small through-the- thickness microcracks in the resin to link with the small air pockets, a moisture path through the facesheet thickness could result. Over time, due to capillary action, moisture can be drawn into the honeycomb cells. Tis moisture build-up, in turn, can further degrade the sandwich panel's overall strength over time due to freeze/thaw cycles and pressure changes. Spirit has worked with material suppliers and its OEM customers and their suppliers to optimize the curing process for OOA sandwich constructions. Spirit AeroSystems credits close coor- dination with customers and material suppliers for much of what has resulted in its high-quality OOA sandwich panels that now exhibit quality equal to that of conventional autoclave-cured panels. Te use of non-foaming adhesives has signif- cantly improved the quality of co-bonded and co-cured structures. A typical honey- comb sandwich panel made by Spirit can be seen in Fig. 5, p. 51. Notably, OOA resin systems provide other advantages, particularly in the area of repair and rework because bonded repairs can be made outside of the auto- clave under vacuum bag only, with local heating. Damaged parts potentially can be cheaply and easily repaired to their full blueprint strength. Toray Industries (Tokyo, Japan) is collaborating with Spirit in testing composite formulations for OOA repairs. Going forward "Cure time is a bottleneck for high- rate production," concludes Cadwell Stancin. In the future, materials must cure much faster and "material chem- istries should be improved to make sure resin fows in a controlled manner through complex architectures and the material systems control knock- down due to variability of fber volume fraction throughout the structure." Spirit AeroSystems is constantly evaluating emerging OOA systems and providing their input back to suppliers in order to improve those systems. As more OOA systems become avail- able and the processes become robust, Cadwell Stancin expects more OOA parts to be developed: "For Spirit AeroSystems, the move to OOA is not a question of if, but only one of when." Read this article online | short.compositesworld.com/SpiritAPW Read more about Inflexion online | short.compositesworld.com/inflexion ABOUT THE AUTHOR David Inston is a CW contrib- uting writer with a composites engineering background spanning almost fve decades. Formerly Composites Materials and Processes Expert at Airbus in the UK, he is now the owner of Epicomp Technology, a composites consultancy based in Weston-super- Mare, UK. david@epicomp.co.uk

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