Topological, Size and Shape Optimization of an Underwing Pylon Spigot

Aircraft pylons have the function of supporting external payloads and are installed under the wing and / or the fuselage. Pylons that are being developed in Alenia Aermacchi will be installed on M-346 new advanced trainer aircraft.

Inside the pylon, the structure called spigot or, in some cases, pivot is a highly stressed structure made of high resistant steel and is the component that transfers the concentrated loads coming from the carried mass to the wing or fuselage structure.

The design activity started from the available space envelope, from the interfaces that were defined as non-design zones and the sizing loads (a set of 26 load cases). The application has been performed using OptiStruct.

The first optimization phase was a 'topological' one. It resulted in the possibility of saving weight removing material in some areas, from a comparison with the already available spigot baseline configuration, in a way that with a standard sizing approach is difficult to imagine.

In a second and final phase, an optimization with the 'shape' approach was conducted. With the present activity an interesting weight reduction (for this kind of structure) of 4.5% has been obtained.

The Author

Marco Basaglia
Aeronautic Engineer
Aermacchi
Alenia Aermacchi S.p.A.
Via Ing. P. Foresio, 1
21040 Venegono Superiore (VA)
Italy

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