PRELIMINARY INVESTIGATION ON THE FEASIBILITY OF A BIRD SURROGATE FOR FULL-SCALE BIRD IMPACT TEST

摘要

The international safety requirements for aircraft certification prescribe the use of flesh-and-bone birds to demonstrate that the most critical parts of the aircraft are able to withstand a birdstrike and guarantee the so called fly-home capability. Full scale birdstrike tests carried out with flash-and-bone birds are difficult to perform and most of the time not repeatable. Thus, in an effort to overcome these problems, a number of research and studies have been carried out to develop bird surrogates. In aircraft industry, bird surrogates are widely diffused and used to preliminarily assess the capability of the structures during their development and to validate numerical model to support and guide the design of new, bird-proof structures. The aim of the present research work was to assess the feasibility of the jelly projectile made of a commercially available ballistic jelly to be used as a surrogate of real bird in full scale birdstrike tests. This particular jelly tends to maintain its own shape without any auxiliary container; it is easy to use and form, can be re-melted and eventually re-used. Initially, referring to previous works on this topic, experimental tests were carried out to investigate the impact forces due to the impact of cylindrical projectile onto a rigid target. In parallel, numerical models of the surrogate bird were created and simulation ran using a proven commercially available code, i.e. LS-Dyna [11]. In this work for the bird modelling the SPH approach was adopted. The bird models were optimized (with regard to the shape and the constitutive law) and validated referring to analytical solutions, previous results from similar research and bibliographical data about flesh-and-bone bird impacts. The experimental data were then compared with analytical solution, numerical results and bibliographical data. As a result, the feasibility of the jelly to be use for creating substitute bird was shown.