Production-based design of a hybrid load introduction element for thin-walled CFRP Structures
- 116 Downloads
The project “Multi-Layer Inserts” (MLI) proposes a new design for inserts used in thin-walled CFRP structures. The proposed inserts consist of multiple thin metal sheets and is build up simultaneously with the laminate in an intrinsic hybridization process, eliminating time-consuming post-processing steps. Furthermore, at equal weight, such inserts greatly increase the bonding area between metal and CFRP in comparison to conventional inserts. This results in a significant increase of the loads that can be transmitted into the CFRP. The present work discusses how the shape of the metal sheets which the proposed inserts consist of influences the mechanical properties of the surrounding laminate. This influence is investigated by measuring the strain distribution during tensile tests by means of digital image correlation. The strain distributions around the following three different MLI design approaches are compared: An elliptical metal sheet, which is expected to be ideal in terms of mechanical performance of the overall structure; a cross-shape metal sheet representing a production-driven simplification which only requires the ability to perform cuts in individual tows perpendicular to the laying direction and can be performed by state-of-the-art AFP systems; and lastly, a compromise between manufacturability and achieved mechanical performance, a decagonal metal sheet design, which requires angled cuts of the fiber tows. It is shown, that the decagon is able to evenly spread the strain over a larger area and is therefore able to significantly reduce the maximum strain values compared to a cross-shape metal sheet, while still being automatable.
KeywordsFiber-metal laminate Automated fiber placement Automation Insert CFRP Embedded load introduction element
This paper is based on investigations of the subproject 1—‘Multilayer Inserts—intrinsic hybrid compounds for load introduction into thin walled high-performance CFRP-Structures’ (DE-447/123-1) of the priority program 1712 ‘Intrinsic hybrid composites for lightweight load-bearings’, which is kindly supported by the German Research Foundation (DFG).
- 1.Banea MD, da Silva LFM (2009) Adhesively bonded joints in composite materials: an overview. Proc Inst Mech Eng Part L J Mater Des Appl 223(1):1–18Google Scholar
- 6.Grützner R, Stefaniak D, Koch SF et al. (2016) Intrinsic hybrid composites for lightweight structures: new process chain approaches. In: WGP congress 2016, vol 1140. Trans Tech Publications, pp 239–246Google Scholar
- 7.Schürmann H (2007) Konstruieren mit Faser-Kunststoff-Verbunden. Springer, BerlinGoogle Scholar
- 8.Volkersen O (1953) Die Schubkraftverteilung in Leim-, Niet-und Bolzenverbindungen. Energie Technik 5(68):103Google Scholar
- 11.Torres MM (2009) Cutting system for strips. World patent WO002009153370A1, 16 June 2009Google Scholar
- 13.3M (2009) Scotch-Weld™ structural adhesive film—technical datasheet: AF 163–2Google Scholar