Effect of Impact Angle for a Bird Strike Case

Abstract

Bird or drone strike are considered as one of the most harsh phenomenon in aviation industry compared to the rest of the aircraft loads like landing or manuvering for both military and commercial flights during its life cycle. Collision in milliseconds results in highly plastic behavior in most of the cases so that flight may face dramatic dynamic scenarios. Statistics show that the probabilty of strike on fuselage, leading edge, engine blades, radome, canopy or windscreen may vary due to the height, speed of the flight and the region. So, crashworthiness studies are carried out to investigate the capability & charachteristics of the material and the design to stand strike loads and prevent possible damages and assure a safe get home landing for multiple cases. Structural integrity is the major goal to design desired characteristics. To ensure this, standards (i.e. EASA 25.631, FAA) describe the specifications including the mass of the bird & impact velocity in addition to the resultant deflection at the component or expected damage. Additionally, test & FEA correlation studies are investigated according to these standards prior to release the final optimized model. In this study, bird strike analyses for multiple impact angles are carried out using explicit finite element software LS-Dyna. Smooth particle hydrodynamics (SPH) technique is implemented instead of arbitrary Lagrangian Eulerian (ALE) methodology to simulate the effect of the impact. Honeycomb and composite parts are included in the leading edge structural FEA model in addition to the metallic parts. The effect of impact angle which may be dominated by attack angle or yaw, roll pitch angles of the flight is going to be investigated. The thin-walled skin of the leading edge made of layered composite subjected to in and out of plane stresses as well while the inner honeycomb structure absorbs energy. On the other hand, metallic parts are modelled using Johnson Cook material model. This work demonstrates some of the outcomes of an ongoing project. Experiment series using high speed cameras is planned to validate precisely builded FEA models.