Objectives  The vibration-isolation thrust bearing is a new device for the longitudinal vibration control of propulsion shafts. Experimental results show that the dynamic transmission characteristics of the propulsion shaft are quite different from those of theoretical calculation predictions. Analysis shows that there is serious vibration energy leakage from the vibration-isolation thrust bearing. For better understanding the cause of poor acoustical property of the system, a study is conducted with the focus upon the flexible assemblies of the thrust bearing to determine directions for optimization improvement design.

  Methods  The dynamic characteristic analysis is conducted concentrated on the coil spring and coil spring cylinder which are key vibration isolation components of the thrust bearing to research the vibration energy leakage. Then, the dynamic model of the coil spring cylinder is established based on both vibration isolation theory and experiment analysis. Moreover, the dynamic characteristic test bench in vertical state is also built up.

  Results  The experimental analysis results show that the vibration resonance peak of the coil spring is sharp and smooth, while that of the coil spring cylinder is flat with more harmonic components induced by contact friction. When there is contact friction, there will be additional stiffness and damping, which significantly change the dynamic characteristics of the coil spring cylinder.

  Conclusion  The dynamic model of the coil spring cylinder is verified by experiments. The dynamic transmission characteristics of the coil spring can be used as an evaluation standard for design improvement. The results of this study can provide theoretical support for the design optimization and improvement of the vibration-isolation thrust bearing, which can have great significance for practical engineering.