Investigation of vulnerability of aircraft structure and materials towards cabin explosions

Damage Tolerance of aircraft fuselage structures has a strong link to explosion resistance. Though accidental explosions can and do occur, intentional explosions are more common as the terrorist threat increases. Structural toughness is as welcome in these scenarios as it is under penetration of non contained engine debris. Guidelines in structural design for such conditions are obviously lacking along with knowledge of typical consequences. The EU-sponsored project VULCAN addresses blast and fire behaviour of civil fuselage structures (cabin) with the aim of achieving significant improvements. This paper deals with blast only. Characterisation and vulnerability of existing monolithic aluminium structures as well as modern laminated materials (Glare, CFRP).is undertaken in this four year program. It aims at understanding typical catastrophic failure behaviour on a dynamic materials and mechanical level and improving this through well-balanced design guidelines. A twofold approach is used, firmly building on a dedicated experimental program and validating and applying numerical simulation tools from there as well. A building block approach was conceived. First level dynamic behaviour is studied at simplified structural and materials level, addressing crack initiation and propagation. A second level introduces increasing complexities due to curvature, stringers frame (castellations) and joints. First test results from the first level are presented, concentrating on dynamic Glare prestressed panel behaviour under a special explosively generated instantaneous large crack. A comparison to a bursting pressurised cylinder as a simple model of a passengers cabin, is ongoing.