High cycle fatigue limit assessment of foreign object damaged aerofoil blades considering the residual stress induced by impact

Abstract

Foreign object damage (FOD) is a critical factor that impacts the operational safety of aero-engine fan blades and is both frequent and inevitable. Therefore, it is necessary to develop an accurate high cycle fatigue (HCF) limit prediction model to enhance the reliability of assessment criteria for fan blades after FOD. Notch and residual stress are the key factors affecting HCF performance. In this paper, FOD tests were conducted to obtain notched airfoil blades and tested their HCF limits. Furthermore, the residual and vibration stress near the aerofoil blade notch were obtained by combining numerical simulation and experiments. The evolution of the residual stress was determined so that the actual stress field near the notch was accurately reconstructed, and the location of the dangerous point was obtained then, based on the theory of critical distance (TCD), an HCF limit prediction model was established and compared with the current Peterson and TCD models without considering residual stress. The results show that the TCD model considering residual stress can accurately predict the HCF limit of FOD aerofoil blades, with an error of 9.70 %±8.66 %, which is lower than the Peterson model (19.60 %±17.56 %) and the TCD model without residual stress (16.58 %±11.62 %).