Evaluation of a substitute bird for engine fan blade impact tests considering the bird-slicing state

Bird ingestion is one of the major threats to aero engines. To evaluate airworthiness compliance in bird ingestion events, dynamic structural tests are the most straightforward and intuitive method. These tests can be conducted using either real birds or substitute birds, the latter offering enhanced repeatability and more convenient test management. In this study, an equivalent strategy is proposed aimed at developing a suitable substitute bird for impact tests on engine fan blades by evaluating the dynamic bird-slicing responses. Two gelatine recipes are adopted to manufacture the substitute birds and the impact responses are measured with a wedge-Hopkinson bar (WHB) system. It is found that the inertial force is the dominant factor in the impact load, and the gelatin resistance also has a certain influence. Generally, the impact responses of the gelatine birds show a constant distribution of the normalized peak impact force with good dispersion as velocity increases. The momentum transfer (MT) exhibits both a “velocity effect” and a “mass effect”, duplicating the responses observed in real bird tests. Besides, the temporal distribution of the force history for the gelatine birds closely matches that of the real birds. The results indicate that the equivalent strategy effectively evaluates the substitution, and the proposed gelatin recipe can be used for real bird alternatives in engine fan blade tests.