Prediction on aeroengine blade foreign object damage validated by air gun tests

Abstract

Aeroengine in service was prone to ingest foreign objects, leading to foreign object damage (FOD) and failure accidents of the blades. In this paper, laboratory FOD tests were firstly conducted on TC4 and AM355 steel simulated airfoil specimens impacted by 3 mm diameter projectile at a speed of 350 m/s, and numerically reproduced using Johnson-Cook (J-C) model with failure criterion. A penetrating-type notch (P-notch) with severe material loss was observed, and a good agreement between experiments and finite element (FE) predictions could be found for both notch morphology and size. The influence of impact velocity on FOD and the FOD-induced residual stress were investigated by the proposed FE model. High tensile stress was observed along the notch edge, while the bottom of notch was mainly dominated by compressive stress. Finally, a FE model of aeroengine blade considering the initial centrifugal force was developed, and the influences of FOD to compressor blade on its modal properties were discussed. Compared to the normal blade, the damage induced a deviation in frequency within 1 %.