Sandwich panels made of Nomex honeycomb core and fiber reinforced face sheets are a major component of aircraft interior parts. A common way to locally increase the strength of such panels, e.g. for load introduction, is the local thickening of the face sheets with additional prepreg layers. Curing of strengthened panels without further processing of the core leads to higher flatness tolerances as well as residual stresses. Machining of the core in the strengthened areas is possible, but expensive due to high machine costs and additional cleaning processes. In this paper a new process for the reduction of the residual stresses in strengthened areas, as well as improved bonding between core and face sheets is presented. The process is based on local reduction of the compressive strength in the surface area of the honeycomb core, which allows for controlled, irreversible deformation at curing pressure. For the reduction of compressive strength, a concept based on a robot guided tool with multiple blades is presented. The process parameters impacting the compressive strength after weakening are derived based on a model based analysis. A testing tool was built, and a series of tests was performed, in order to quantify the impact and to select suitable parameters. It was found that the remaining compressive strength depends mainly on the cutting pattern, the blade distance and the cutting depth. A Further reduction of compressive strength was achieved by bending the remaining structures after the cutting process. In order to validate the process, surface flatness, as well as bonding strength between core and face sheets have been measured. In addition to the flat integration of a large amount of additional prepreg layers it has been found that the bonding strength increases up to 30% due to increased bonding surface of the honeycomb core.


    Zugriff

    Zugriff prüfen

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Local Weakening of Honeycomb Core for Improved Surface Quality and Bonding in Co-Cured Sandwich Panels


    Weitere Titelangaben:

    Sae Int. J. Adv. and Curr. Prac. in Mobility


    Beteiligte:

    Kongress:

    AeroTech Europe ; 2019



    Erscheinungsdatum :

    2019-09-16


    Format / Umfang :

    12 pages




    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




    Failure of Alternate Honeycomb Core Sandwich Panels

    Shah, Udit / Kapania, Rakesh K. | AIAA | 2019


    Improved bonding of honeycomb panels

    Sobkiewicz, S. A. | NTRS | 1977


    Static Analysis of Sandwich Panels with Square Honeycomb Core

    Kapania, Rakesh K. / Soliman, Hazem E. / Vasudeva, Summit et al. | AIAA | 2008


    Failure of Hexagonal and Triangular Honeycomb Core Sandwich Panels

    Shah, Udit B. / Kapania, Rakesh K. | AIAA | 2020