Modal behaviour of rotor considering rotary inertia and shear effects

Abstract

Summary The effect of rotary inertia and shear effect becomes an important aspect for heavy rotors. The Euler–Bernoulli beam element is used for approximation in case of slender rotors and it is necessary for heavy rotors to consider rotary inertia and shear effect. These effects tend to change the mass and stiffness matrix of shaft element. This paper presents the comparison of modal behaviour using Rayleigh beam element which includes rotary inertia effect, Timoshenko beam element which includes both rotary inertia and shear effect with Euler–Bernoulli beam element which excludes both rotary inertia and shear effect. The convergence of first three natural frequencies is shown and the results are compared with the experimental modal analysis data. Upon comparison of the results it is confirmed that rotary inertia and shear effect gives more accurate results and should be included for the analytical calculation of dynamic parameters of rotor system.