Dynamic analysis of a quasi-zero stiffness vibration isolator in propulsion shaft system

The propulsion shaft system is a vital component of underwater vehicles. The longitudinal vibration transferred from the propulsion shaft to the bearing housing affects the reliability of underwater vehicles and the sensitivity of detection equipment. The quasi-zero stiffness (QZS) vibration isolator has extremely excellent isolation performance, but it has not been applied in propulsion shaft systems yet. This work establishes a propulsion shaft system dynamic model with QZS vibration isolator and proposes a QZS vibration isolator with a wider QZS zone. The accuracy of the proposed vibration isolator force-displacement characteristic calculation model is confirmed by comparing with the ADAMS results. Moreover, the vibrations of the bearing outer raceway and housing are considered in the dynamic model. The dynamic model in this work is verified by an experiment. The bearing housing accelerations and displacements with and without a QZS vibration isolator are compared to show the isolation performance and application possibilities. In addition, a transverse vibrations analysis and a run-up analysis are conducted. This work provides an effective way to isolate longitudinal vibration transferred from the propulsion shaft to housing.