Innovative process to fabricate curved aluminium frames reducing buy to fly and geometrical distortions
Gabriella Caputo, Francesco Passeggio, Giancarlo Ingenito, Sabato Inserra Imparato, Fatima Cicchiello
Abstract. Curved frame with complex sections are used on critical zone of aerospace structure like connection of main pressure bulkhead to fuselage barrel and door surround. Most of these frames are produced from aluminum alloy like 7075 or 7050. The production of these parts with curved shape and complex section poses technical and economical challenges in their production. In fact, from one side it is necessary to meet strict geometrical tolerances and structural requirements while from the other it is necessary to contain the cost in terms of raw material and fabrication process. This issue has been afforded to produce curved aluminum frame to be used to connect a composite pressure bulkhead to a composite fuselage. These frames have a Y-shaped section to allow joining of pressure bulkhead to fuselage barrel with a unique element. Due to the curvature, length and section it was not possible to machine the frame from a flat plate of suitable thickness. In fact, the necessary thickness would be greater then maximum for which structural allowable are available. Therefore, having in the industrial plant the availability of all necessary equipment and facilities to meet the requirements, it has been developed an innovative fabrication process involving: heat treatments, calendering of high thickness plate, precision machining to obtain the required geometry, tailored shoot peening to recovery unbalanced stress deriving from machining. Development has been performed trough some preliminary full-scale tests in which the main process steps and their relevant parameters were optimized with results confirmed, producing a significant lot of parts. Moreover, some manual and FEM analysis on the concerned frame have been performed to correlate tailored shot peening with residual stress compensation. The work performed allowed to define an innovative process dedicated to fabricate long curved aluminum frame with complex section reducing material waste and obtaining the required geometrical tolerance and structural allowable. For each step of the process the relevant parameters has been established by experimental test on full-scale parts. A method to correlate tailored shot peening intensity and location with recovery of geometry out of tolerances due to residual stress has been identified.
Keywords
Complex Section Metallic Frames Fabrication, Tailored Shot Peening, Heat Treatments
Published online 5/7/2025, 10 pages
Copyright © 2025 by the author(s)
Published under license by Materials Research Forum LLC., Millersville PA, USA
Citation: Gabriella Caputo, Francesco Passeggio, Giancarlo Ingenito, Sabato Inserra Imparato, Fatima Cicchiello, Innovative process to fabricate curved aluminium frames reducing buy to fly and geometrical distortions, Materials Research Proceedings, Vol. 54, pp 1836-1845, 2025
DOI: https://doi.org/10.21741/9781644903599-197
The article was published as article 197 of the book Material Forming
Content from this work may be used under the terms of the Creative Commons Attribution 3.0 license. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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