EADS Innovation Works is reviewing options for the materials Airbus could use on an airplane to replace the A320neo in 2022. The competition between metal and composites remains intense, prompting EADS IW boss Yann Barbaux to advise against betting on a full-composite airplane, now designated the A30X.
Speaking at a conference organized by the French Air and Space Academy in Paris, Barbaux explained that weight savings come at a less acceptable cost for a medium-haul airplane than on long-haul aircraft such as the A350. Removing a kilogram from an airframe saves more fuel on a long-distance flight, he added. Aluminum alloys, therefore, could prove more suitable than composites for the A30X’s thin parts, such as the fuselage. Thicker parts such as wings would more readily lend themselves to pricier, but lighter carbon-fiber reinforced plastics (CFRP).
In alloys, aluminum-magnesium-scandium has emerged as one candidate. “No copper means no corrosion,” Barbaux said. Challenges include scandium’s price and limited global availability.
In CFRP, thermoplastics (as opposed to thermosets) make good candidates for the nose section, and the EADS IW-sponsored Technocampus research center in Nantes, France, has built a double-curvature demonstrator of the part. The benefits, expected to offset higher costs, include damage tolerance, easier manufacturing, weldability and environmental friendliness.
New processes could help save weight, too. For example, additive layer manufacturing (ALM, sometimes oversimplified as 3-D printing) might ease the production of parts with complex shapes and could prove appropriate for pieces of equipment and parts such as air ducts. “Integrating [component] functions, which cuts the part count, and topology optimization can provide important weight and cost savings,” Barbaux told AIN. Optimizing topology–the study of the properties of geometric forms that don’t change under transformations such as stretching or bending–involves creating a part whose anatomy better takes into account the actual loads the part endures.
Large-scale production using ALM remains infeasible, however, although researchers estimate that could change in five to 10 years. Even by then, they don’t think ALM advances will allow for its use in primary structures.
In assembly, friction-stir welding (FSW) might replace riveting. Airbus has started using FSW on the A400M military transport for floor panels, Barbaux said. The process can save 0.7 kilograms per meter (0.47 pound/foot) of junction line. On the A30X, FSW could become an attractive option, especially for “rib one” in the fuselage-wing mating area.