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Numerical Simulation and Design Optimization of a Lower Fuselage Structure with Advanced Integral Stiffening

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Aircrafts — optimising manufacture

Aircrafts — optimising manufacture

Industrial Technologies

Reducing the weight of aircraft can provide important reductions in fuel consumption and associated emissions. EU-funded scientists initiated the project (FUSDESOPT) to evaluate relevant manufacturing methods and structural loads associated with the lower fuselage of an aircraft. Scientists compared laser beam welding technologies with conventional riveting for thin-walled metallic structures with stiffening elements (stringers) to determine the potential mass savings. They implemented conventional hand calculations first and then analysed the utility, accuracy and computational load of various 2D and 3D finite element method models. Researchers compared the failure modes of welded stringer configurations predicted by 2D pull-tests with the 3D analyses of panel compression. Panel compression is used to test the dominant static load of aircraft fuselage components. Differences in predicted local failure modes demonstrated that the strength of 3D compression panels cannot be interpolated from 2D pull-test specimens. However, the 2D analyses are valuable for assessing the relative strength of materials and of joints in general. Resistance to structural deformation in pull-test loading suggests good resistance to stringer rotation. Partners compared a 3D shell model with a 3D solid model to optimise the trade-off between computational load and accuracy. Shell finite elements modelled global behaviours in large regions well in a relatively short time of only a few hours. However, they could not capture the local failures of weld seams with required accuracy. FUSDESOPT highlighted the advantages and disadvantages of various models of light-weight, stringer-reinforced fuselage components in evaluating laser beam welding versus conventional riveting. Further optimisation of codes to balance accuracy with computational load will facilitate faster development of better designs. Lighter fuselage weight leading to decreased fuel consumption and emissions will benefit the environment. It will also enhance the global competitive position of the EU aircraft industry that is facing an increasingly green consumer profile.

Keywords

Light-weight, aircraft, laser beam, welding, riveting, stringers, finite element, failure, panel compression

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