Investigation of effects of bird strike problem on wing leading edge by using explicit finite element method

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2015
Dede, Oğuzhan
In aviation industry, bird strike problem causes structural damage and threats to flight safety. Nowadays, designed and produced aircraft have to satisfy “safe flight and landing” requirements. The behavior of the aircraft components during bird strike have be to investigated by numerical methods or experiments. Results obtained from numerical analysis and /or experiments have to be carefully studied to optimize the aircraft structures. However, experiments of bird strike are very costly and require qualified test infrastructures. Also, trial and error method is used in test procedures and it leads to consumption of time and money for aircraft producers. Use of finite element method is continuously increasing to analyze bird strike problems to reduce time and money requirement to validate aircraft structures. The main aim of this thesis is to apply the explicit finite element analysis procedure for the analysis of bird strike problem on the leading edge of the wing. In addition, another aim of this thesis is to show capabilities and effectiveness of honeycomb material against bird strike when used in the leading edge. For this purpose, LSTC Ls-Dyna is chosen as the explicit finite element solver for the bird strike analysis. To model the soft body impactor (bird), a small benchmark study is performed among different solution formulations such as Eulerian, ALE (Arbitrary Lagrangian Eulerian) and SPH (Smoothed Particle Hydrodynamics). As results of the benchmark study, SPH is chosen as the suitable formulation to model the bird by comparing the deformation and impact force results. Similarly, suitable material model is selected to model the metallic aircraft structure by conducting a benchmark study between elasto-plastic and elasto-viscoplastic material models. Johnson Cook material model is decided to be used for modeling of metallic aircraft structures. Additionally, laminated composite fabric material model which is available in Ls-Dyna material model library is used for modeling the composite wing leading edge. Material characterization test results are used to determine material parameters and coupon simulations are performed to validate material model of the composite fabric material. After the selection of suitable solution formulation for soft body impactor and material models for metallic and composite aircraft structure, bird strike analyses on the wing leading edge are performed for both metallic and composite case studies. Effect of bird strike is investigated for metallic and composite leading edges and it is clearly seen that bird strike problem may lead to catastrophic failure during flight if proper design measures are not taken. Finally, reinforcement study of the wing leading edge is done by using the honeycomb material. Honeycomb material is added to metallic and composite wing leading edge and bird strike analyses repeated to investigate the effect of honeycomb on the bird strike problem. It is seen that honeycomb exhibits excellent stiffness against soft body impact. It is concluded that honeycomb materials are very effective materials for bird strike problem with low ratio of weight / impact stiffness.
Citation Formats
O. Dede, “Investigation of effects of bird strike problem on wing leading edge by using explicit finite element method,” M.S. - Master of Science, Middle East Technical University, 2015.