This study investigates the effects of low-cycle and high-cycle fatigue interaction on the aerodynamic and structural behaviour of a fan blade. A numerically based analysis through the interfacing of computational fluid dynamics (CFD) and finite element modelling (FEM) analysis, referred to as fluid-structure interaction (FSI) is performed in order to estimate the fatigue life of the blade. This paper reports initial results from an ongoing study on numerical simulations of one-way FSI to predict representative fluctuating loads on the fan rotor blades of the first axial compressor stage of a representative gas turbine engine. The stator blade is modelled upstream of the rotor blades to simulate the turbulent shedding of wakes that result in aerodynamically induced vibrations of the rotor blades, a leading cause of high-cycle fatigue. The rotor blades are also subject to low-cycle fatigue induced by both the high rotational loads and the mean aerodynamic pressure loading experienced by the blades at various operating conditions. The transient results reflect the oscillatory nature of the pressure loads and resulting stresses on the blades. A stress-life analysis used to estimate the fatigue life of the blade based on the stresses from the FSI analysis shows that it has the potential to be a useful tool in determining the effect of an HCF and LCF interaction on the fatigue life of rotating components.
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