A numerical and experimental approach to optimise sheet stamping technologies: part II — aluminium alloys rubber-forming

The conventional way to develop press-formed metallic components requires a burdensome trial-and-error process for setting-up the technology, whose success chiefly depends on operatorʹs skill and experience. In the aeronautical field, where sheet metal press-formed structures are produced in small series, a too lengthy and costly development phase cannot be accepted; the small number of components not allowing the investments depreciation. For these reasons, it is necessary that, during the conceptual design, possible technological troubles are preliminarily faced by means of numerical simulations. In the following report, the Guérin rubber-forming process of an aluminium alloy fuselage frame belonging to AerMacchi MB-339 trainer aircraft was optimised through this approach. Several effects, depending on stamping velocity, component geometry, sheet metal heat treatment, elastomeric rubber pad constitutive law and thickness are taken into account. It is shown how the preliminary tuning of these parameters allows us to minimise defects, increase component quality and reduce set-up times, complying at the same time to the demanding aeronautical requirements.