Modeling crack growth of an aircraft engine high pressure compressor blade under combined HCF and LCF loading

This paper presents a 3D crack growth simulation of an aircraft engine high pressure compressor blade which fractured in service. Using FRANC3D, an initial crack is inserted and grown using the max tensile stress theory. A numerical method was developed to capture the stress field under low cycle fatigue (LCF) and high cycle fatigue (HCF) loading by superimposing test measured dynamic loading with steady stresses. In doing so, the predicted crack trajectory, aspect ratio, and shape more closely agreed with the fractured airfoils compared to performing the simulation under LCF loads alone. This supports findings from fractographic investigation that the crack exhibits HCF rather than LCF characteristics.