MODAL CHARACTERISTICS OF CRACKED ROTORS USING A CONICAL SHAFT FINITE-ELEMENT

A finite element model of a tapered rotating cracked shaft is develope d for modal analysis and dynamic modeling of rotor-bearing systems. Th e finite shaft element has ten degrees of freedom and accounts for lin ear tapering. The flexibility compliance due to the crack is computed using fracture mechanics approach. The formulation of the tapered rota ting cracked finite element includes shear deformation and rotary iner tia. The shape functions are derived and explicit expressions for the element mass, stiffness and gyroscopic matrices are obtained using con sistent mass formulation. The generalized eigenvalue problem is define d and numerical solutions are obtained for a wide range of whirl ratio s, crack depths and crack locations. Comparisons with other results re ported in the literature are presented. (C) 1998 Elsevier Science S.A. All rights reserved.