Dynamic effects of the initial skewness of the inertial principal axis on the rotor with bolted joint

Rotary inertia moment excitation is a potential source of vibration in rotating machinery. It can be caused by the initial skewness of the inertial principal axis on the rotor disk, which results from machining errors and assembly misalignments. This study investigates the dynamic behavior of the bolt-connected rotor system with an initial disk skewness of the inertial principal axis. A detailed analysis of the mechanism of the rotary inertia load is presented, and an equivalent nonlinear joint element is proposed and integrated into the lumped rotor model. The dynamic behavior of the rotor system with local rotary inertia excitation load, which considers both the lateral force and the angular moment, was thoroughly analyzed. A Jeffcott rotor test rig with an adjustable disk assembling skewness angle was proposed, and experiments on the rotor with local rotary inertia load were conducted for validation. The results indicate that the dynamic response on the bearing increased more rapidly with a larger assembling skewness angle. For the relatively looser assembling configuration, the joint slipped and deformed after the rotation speed exceeded a threshold value, which decreased with the growth of the skewness angle, and exhibited a resonance-like peak at the supercritical speed range.