Investigation of Several Impact Angles for Predicting Bird-Strike Damage in a Riveted eVTOL Composite Wing

  • Kayar, Eray (Queens University Belfast)
  • Abdelal, Gasser (Queens University Belfast)
  • Falzon, Brian (RMIT University)
  • Kazancı, Zafer (Queens University Belfast)

In session: - Impact

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The structural integrity of composite airframes has once again come under scrutiny with the introduction of hybrid or fully electrical aircraft, including eVTOLs, where lightweighting continues to be a primary design driver. Despite the extensive use of composites in the latest generation of large passenger aircraft, some composite structural elements are still more prone to damage, arising from off-design loading, than their metallic equivalents. For instance, the leading edges of wings, horizontal stabilizer and empennage, are particularly vulnerable to bird strikes [1]. Consequently, such composite structures are usually fitted with metallic leading edges. Nevertheless, pursuing a composite leading edge has benefits, such as greater weight reduction and improved laminar flow. It is crucial to ensure that its energy absorption characteristics are investigated thoroughly. To minimise the amount of physical testing in qualifying a composite leading edge, reliable and accessible computational modelling tools are required. In compliance with international standards and special conditions specified by EASA, a composite sandwich wing model, built of unidirectional carbon-fibre polymer composite and a phenolic-based honeycomb core material, is simulated under soft body impact conditions. Unidirectional prepreg materials are used in the lay-up of the wing model's face and rear skin as well as the connection area that joins the spar and the leading edge. Homogeneous gelatin characteristics, and a well-defined equation of state model, are used to configure the soft body mass (substitute bird model). An explicit finite element solver, LS-Dyna was used to carry out the analyses. Soft body impact, to simulate a bird strike, is achieved using Smooth Particle Hydrodynamics (SPH). The comparison of failure initiation of five cases including the normal and oblique 12.5, -12,5, 25 and -25 degrees for a riveted wing leading edge model of an eVTOL are investigated ply by ply. Investigation is also conducted into the potential failure mechanisms [2] for the joints of mechanically fastened unidirectional composites, including bearing and bolt failure as well as net section, shear out, bolt pulling through the laminate, and cleavage tension.