Analysis of bird strike on a wing leading edge made of fiber metal laminates

Aircraft structures, likely to be subjected to bird strike, have to satisfy a series of requirements defined in terms of structural resistance. One of the most critical areas of the aircraft is the leading edge of the wing. The main requirements states that birds should not penetrate the leading edge of a wing or, in case of penetration, no critical damage should be induced to the front spar. Certification for bird strike is mainly achieved by experimental test, but numerical simulations provide an invaluable tool to evaluate designs and to reduce the cost of the experimental programme. However, numerical simulations must be able to predict very large structural deformations, including the case of complete bird’s penetration of the aircraft leading edge. In a collaborative research project between universities and industrial partners, an aircraft wing leading edge structures with a fiber-metal laminate (FML) skin was designed with the help of finite element analysis, subsequently built, and then subjected to bird strike tests. The study was driven by the industrial demand to improve the design rules necessary for the preliminary evaluation of the structural response of a leading edge of a new aircraft, when subject to bird strike. Several configuration of a one-bay component of a typical wing leading edge was prepared and tested at Alenia plant. Various materials, lay-up distribution and boundary conditions were investigated. Analysis of the suitable sensor distribution was also additionally performed for the best possible numerical correlation approach. The numerical finite element simulations were performed using the commercial explicit integration code MSc/Dytran. The paper describes the basic assumptions of the analyses, i.e. bird properties, composite failure modes, and the way in which the simulations have been carried out in an industrial environment. Preliminary numerical simulations were able to predict that the bird did not penetrate the leading edge skin. The simulations included the leading edge and the structure supporting the test article. The final correlation between numerical and experimental showed that good correlation was achieved, in terms of global structural behaviour of the test article, confirming the validity of the approach.