G. Surdon, Dassault Aviation, Argenteuil, France; E. Gratiot, Dassault Aviation, Saint Cloud, France; F. Eberl, Alcan, Voreppe, France

Summary:

Age Forming is a process that involves simultaneous forming and artificial aging, mainly used for top wing skin panels of commercial aircraft and business jets. The age forming process can be performed for any artificially aged aluminum alloy. However, this process could change the material properties (degradation of the toughness and damage tolerance) and might not be suitable for aerospace applications such as bottom wing skin panels. Up to now, these constraints lead to limited application of the ageforming process of aerospace parts, which are mainly static strength driven.

Lower wing skins of commercial aircraft are currently formed by conventional forming processes as cold working or peen forming using 2024T351. The recently developed alloy 2022 is ageformable using the T8 temper and shows improved properties compared to current 2024T351. In order to reduce manufacturing and assembly costs and to improve the structure performance (in service properties and weight), the use of integral components as machined stiffened panels coupled to the age forming process appears as an innovative manufacturing route. This paper presents results on the age formability of 2022 alloy supported by forming tests on un-stiffened, stiffened coupons and complex panels. Relaxation tests complete the characterization of ageformability of the 2022 alloy. A focus on the robustness is shown in order to define the industrial process window. After determination of the constitutive laws, numerical simulation of age forming is carried out to determine the strain and residual stress distribution. Finally, the post aged material properties of 2022 T8 are compared to 2024T351 This development is supported by the European project, AGEFORM.