Stiffness Variation of a Cracked Rotor with a Semi-Elliptical Front

Abstract

The purpose of this paper is to determine the variation of stiffness coefficients of a rotor containing a transverse crack with a semi-elliptical front. The crack front was considered to be straight in previous research efforts; however, the crack grows in an elliptical path when the rotor is subjected to cyclic loads, as determined through fatigue experiments and realistic cases. Therefore, considering the effect of a semi-elliptical surface crack, the dynamics of a semi-elliptical and straight cracked rotor are modelled using the finite element method, and the local flexibility introduced by the cracks are determined by the strain energy release rate (SERR). Finally, the comparative study of the stiffness variation for both types of cracked rotors exhibit the characteristics of crack breathing behaviour, and crack breathing has a significant influence on the variation of the direct and coupled stiffness.