A New Design Principle For Damage Tolerant Structural Bonding In Aerospace Applications

Abstract

The main obstacle of introducing structural bondings in aerospace applications is its damage tolerance behavior as in case of damages a potential crack can grow in an un-controlled manner to a critical size. At Airbus Helicopters a purely geometrical adaption of a single lap shear bond line was developed which stops a potential crack-growth effectively and reliably. The main principle is based upon splitting up the bond line along its length into several sub-bondings. The separation of the individual sub-bondings is achieved by an intermeshing pattern of both ends of the panels (for example a zig-zag-line) which are connected to the splice plate. At this zig-zag line cracks cannot propagate anymore and thus are stopped effectively. Additional benefit of the inter-meshing pattern is that the stress peaks are reduced significantly compared to the common constant overlap. It is demonstrated by analysis and test that the new design principle is limiting crack growth in the bond line and increases the load transfer capability at the same time.