Design and optimisation of the external load bearing carry through structure of a columned multi bubble fuselage

摘要

The blended wing-body configuration holds a major structural design challenge at the centre-body where the structure must support both wing bending loads and internal cabin pressure. A membrane approach is proposed which decouples the loads to allow their resistance by two independent structures: an inner membrane for cabin pressure and an outer structure to resist wing loads. A columned multi-bubble fuselage is proposed for the inner membrane structure, which are multispherical configuration to efficiently withstand the pressure loads. Considering this configuration, the carry-through structure can be designed and optimised. Finite element results show a significant reduction of stress level in this design over that for a conventional multi-bubble fuselage. Up to 30% weight reduction is achieved for a military cargo application that requires an extensive area with no structural interruption. For the outer carry-through structure, the topology and shape optimisations of finite element models were performed on the given design domain. The results from the shape and topology optimisations were complementary demonstrating a consistent design approach. The optimisation theory is briefly presented along with the results.