Bird strike on aeroengine fan blades: a combined experimental and numerical study

Bird strike damage as a significant safety concern has been widely focused on during the service life of aeroengines. This research enhances traditional analysis methodologies to accurately predict and assess fan blade damage characteristics. Firstly, the dynamic mechanical properties of TC6 titanium alloy were determined through comprehensive material testing. Using multi-objective optimization methods, a high-precision modified Johnson-Cook constitutive model (MJC) and fracture model were developed for fan blades. Material parameters and numerical models were validated through gelatin bird impact tests on static single blades. Then, numerical simulations analyzed blade-bird cutting effects, with particular emphasis on rotation speed and bird velocity impacts. Results demonstrated that the resultant velocity deviation angle and blade twist angle significantly influence blade damage patterns. Therefore, this study presents an impact interaction mechanism that explains the counterintuitive phenomenon of increased blade damage under reduced rotation speed and bird velocity conditions. Subsequently, expressions for average impact force and root stress were derived from fundamental bird strike parameters, quantifying both impact loads and root stress concentration levels. Finally, compressor impact simulations revealed that bird fragments significantly affect stator blades positioned behind the fan blades. These findings provide valuable reference points for bird-strike resistance analysis and aeroengine fan blade design optimization.