CompositesWorld
Issue link: https://cw.epubxp.com/i/866813
SEPTEMBER 2017 92 CompositesWorld INSIDE MANUFACTURING in fatigue — so weight is at least 15% to as much as 25% less than aluminum alone. Because of the lighter weight, panels can be made larger, spanning larger areas of the fuselage. Larger, thinner panels provide cascading benefits throughout the airframe, because fewer brackets, supporting ribs and fasteners are required, and assembly can be accom- plished faster. e use of Glare on the upper fuselage of the Airbus A380, for example, saved more than 1,000 kg, compared to aluminum, and the material has performed better than aluminum alone with regard to lightning strike and under the tension loads imposed on the fuselage by passenger cabin pressuriza- tion cycles during aircraft service. Van Mourik points out that the economics of FMLs fit best with heavily scheduled commercial aircraft, where "FMLs reduce cost of ownership for airlines because of better fatigue perfor- mance, and much longer inspection intervals can be put in place, which saves on maintenance." Longer fatigue life and weight savings, he notes, aren't as critical to owners of business jets or general aviation aircraft. ere is one sticking point: For now, Airbus is the sole customer for glass-rein- forced FMLs, due primarily to arrange- ments made with the OEM when it invested in the material's development. Also, patents have limited its applications to aircraft built in Europe, although that situation might change, going forward. Nevertheless, van Mourik asserts, "We believe the properties of FML and its additional interlinked advantages make it the best fuselage material, with the best design principle." And it may be the ideal material choice for new narrowbody aircraft fuselage structure, he explains. "Fiber-reinforced polymer composites require a minimum thickness to resist damage," he points out, "so while they made sense for larger twin-aisles, they are not the logical choice for smaller narrow- body craft," says van Mourik, adding, "at minimum skin thickness takes away composites' weight advantage." FMLs also offer some distinct processing and cost advantages. example, around windows or doors or at frame locations where fasteners will be used — additional layers can be added internally, or additional FML layers can be bonded on the outside of a panel, as doublers." Layups are vacuum bagged, then transferred to the autoclave. Cure takes 3.5 hours at 120°C for standard Glare (up to 180°C for High Static Strength Glare), with a ramp rate of 2-5°C/min at 11 bar. Following cure and demolding, panels undergo C-Scan inspection, followed by another round of milling, to ensure a smooth surface. Finally, panels are painted, then expedited to customer assembly locations. A new generation of hybrid material FML panels are ultimately thinner than aluminum alone because they perform better Achieve a higher level of efficiency with innovative materials from BASF. Labor and cost savings, increased passenger comfort, and design flexibility are just a few of the ways we deliver solutions to the entire value chain. At BASF, we create chemistry. aerospace.basf.com We create chemistry to build lightweight space saving interiors.