12 AEROSPACEMANUFACTURING | NOvEMbER 2009
Metallics i Joining
Aluminium
FIGhTS bACk!
Pocket milling manoeuvres: Machined aluminium ribs for the Airbus A380
Dr Neil Calder discovers that while titanium and carbon composites still vie for
dominance in the manufacture of sustainable aerostructures, aluminium remains well
positioned to produce components like wing ribs with realistic weight/cost trade-offs.
T
here have always been tensions the aluminium industry has not been well positioned to produce affordable
between the various material standing still. As a global supplier of aerostructures with its realistic weight/
camps in aerostructure design aluminium material and technology cost trade-off and wing ribs have
since the supply and expertise in and Europe’s major player in this field, persistently been designed in this
production and processing of material Alcan has been visibly active through its material.
types has generally come from research centre in Voreppe, France.
completely different places, and has been Recently designed civil aerostructures Lithium lightens the way
the product of different organisations for the B787 and A350 have highlighted A high potential approach for alloy
and individuals. the interactions between the various performance improvements has been in
Long ago, towards the end of the material types and the differing ways the optimisation of Al-Cu-Li-(Mg-Ag-
1920s, spruce was displaced in favour in which the eternal engineering Zn) alloys where every weight percent
of duralumin. After the Second World compromises are resolved. Carbon fibre of lithium in the alloy results in a 4%
War, titanium displaced some uses of composite components in the fuselage reduction in density of the metal. This
aluminium and medium strength steels and wing structures of these aircraft third generation of lithium bearing
and more recently carbon composites have been designed to interface with alloys has been developed as damage
have disrupted the balance yet again. titanium parts where possible. Alcan’s tolerant variants of military and space
Apart from the possibility of resurgence development personnel cite a shortfall metals in order to meet the demands of
in the use of natural wood as the in development time for the technology future commercial airframes. AA2198
ultimate in sustainable manufacturing portfolios of these aircraft as the reason and AA2050 are typical of these damage
of aerostructures, this leaves the three for the extensive use of titanium and tolerance alloys. Material performance
major material categories of aluminium, carbon fibre in inner structures as there improvements are only part of the
titanium and carbon still trying to are less compatibility issues with this potential developments of metallic
achieve an optimum balance. material pairing, particularly regarding solutions for airframes however, with
In responding to the worldwide corrosion and thermal expansion. gains of similar magnitude in component
prevalence of carbon fibre composites, Aluminium, however, still remains weight and cost achievable by applying
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