Vibration analysis of a rotating pre-twisted blade considering the coupling effects of stretching, bending, and torsion

Abstract

An enhanced dynamic model for a rotating pre-twisted blade with arbitrary cross-section is proposed in this study. The coupling effects between stretching, bending, and torsion are considered simultaneously in this model. To derive the equations of motion, deformation variables, including a special variable representing stretch, are approximated using the assumed mode method. The stretch variable plays a key role in the coupling effects between stretching, bending, and torsion. The accuracy of the proposed model was validated by comparing the analysis results to those obtained using a commercial finite element code. The effects of several parameters, such as cross-section eccentricity, pre-twist angle, torsion to bending stiffness ratio, and angular speed, on the modal characteristics of the blade were investigated using the proposed model. It was found that coupled modal characteristics of a rotating pre-twisted blade could be accurately estimated with the proposed model.