Wing joint design is one of the most critical areas in aircraft structures. Efficient anddamage tolerant wing-fuselage integration structure, applicable to the next generation oftransport aircraft, will facilitate the realisation of the benefits offered by new aircraftconcepts. The Blended Wing Body (BWB) aircraft concept represents a potentialrevolution in subsonic transport efficiency for large airplanes. Studies have shown theBWB to be superior to conventional airframes in all key measures. Apart from theaerodynamic advantages, the BWB aircraft also provides a platform for wing-fuselagedesign changes.The main objective of this research is to design a damage tolerant wing-fuselage jointwith a novel bird’s mouth termination for a BWB aircraft that has a similar payloadrange to the B767 aircraft. The damage tolerance analysis of the proposed BWBwing/fuselage integration structure includes assessments of fatigue crack growth life,residual strength and inspection capability.The proposed structure includes a bird’s mouth termination of the spars that facilitatessmooth transfer of loading from the spar web into the root rib and the upper and lowerskins and is novel in its application to the blended wing body configuration. A finiteelement analysis was required to determine local stresses for the prediction of fatiguecrack growth life, residual strength and inspection capability and to identify weak spotsin the proposed structure. The project aircraft wing comprises of three spars (front,centre and rear) and a false rear spar thus defining a four cell wing box. Wing rootshear, bending moment and torque loads were derived and applied to a thin-walled threebox idealisation of the proposed structure. The challenges experienced in replicating theloads obtained from the three box idealisation were addressed by modification of theboundary conditions. Checks for compression and shear buckling were also undertakenthat confirmed that the applied loads were below the limits of the proposed structure.The finite element analysis showed very clearly that the stresses in the novel bird’smouth spar termination were significantly lower than in the skin and that the skinremained the more critical damage tolerant component at the wing root when thestructure was subjected to ultimate design stresses. The spar web at the bird’s mouthtermination was shown to have a larger crack growth life compared to the skin. Thethickness of the skin requires further investigation as a significant amount of localbending was experienced due to the applied pressure. The skin will sustain a two-baycrack at the design limit load thus proving the proposed wing fuselage integrationstructure to be damage tolerant.In conclusion, the main objective of the thesis has been achieved. An integrated wingfuselagejoint with novel bird’s mouth spar termination and surrounding structure havebeen designed and substantiated (evaluated) by damage tolerance requirements.
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