Advanced Alloys and Composites

Bombardier, Airbus

From the mid-1980s onward, there has been a steady increase in the use of non-metallic fiber-reinforced plastics such as carbon-fiber reinforced polymer (CFRP) composites. A series of new heat-treated alloys and lighter-weight aluminum-lithium alloys have been developed to counter the composite challenge, the latter weighing around 10% less than the widely used 2000 series alloys used in various forms for aircraft since the 1920s, while retaining the same strength as the 7000 series. Despite positive stiffness, fatigue and corrosion properties, the use of Al-Li has been limited, largely due to high lithium production costs. The material was, however, selected by Bombardier for the fuselage skins of the C Series; for future single-aisle designs Al-Li is expected to be cost competitive with composites. A hybrid material incorporating fiber and aluminum, called Glare, was selected by Airbus for the fatigue-critical upper-fuselage skin sections of the A380. Composites are now increasingly used in primary structures; they form 50% of the 787 airframe and 53% of the A350’s.