Dynamic analysis of cracked rotating blade using cracked beam element

Abstract

In this paper, the dynamic model of a pre-twisted cracked rotating blade is established using self-programed beam element (CBE) and its nonlinear characteristics are analyzed. Firstly, based on the Castigliano’s theorem, the CBE with an open crack model is established. Secondly, a new breathing model of CBE is proposed in terms of the change of the crack contact region. Subsequently, the finite element (FE) model of a pre-twisted cracked rotating blade is established, and then verified by the ANSYS model. Finally, the effects of the crack depth, the crack position, the aerodynamic amplitude and the rotating speed on blade vibration characteristics and crack breathing status are investigated. The results show that the proposed model relative to the ANSYS model is of high efficiency and accuracy, besides, the larger crack depth and higher rotating speed result in a non-breathing crack, while the larger crack position and aerodynamic amplitude result in a breathing crack.

Keywords

• Finite element method
• Cracked rotating blade
• Cracked beam element
• Nonlinear vibration
• Breathing effect