A novel methodology for bending ultrasonic fatigue testing in the VHCF regime

Deep research on the bending fatigue behaviors of rotor blade materials in the very-high-cycle fatigue (VHCF) regime is necessary for designing the blade. In this study, a new cantilever specimen with variable thickness and the corresponding methodology based on the Timoshenko beam theory and the transfer matrix method are proposed for bending ultrasonic fatigue testing in the VHCF regime. This methodology is applied to achieve the desired second-order stress state and to estimate the stress by displacement. The feasibility and applicability of the methodology are demonstrated by the results of Finite Element Analysis and the experimental results from Ti-6Al-4V specimens.