Influence of boundary conditions on the value of the natural frequency of transverse vibrations of the ship's shaft line

Abstract

The paper studies the effect of the flexibility of the shaft bearings on the performance of the entire ship's shaft line. It analyzes the existing values of the stiffness coefficient used for elastic stops in the calculation schemes for calculating lateral vibrations and centering the ship's shaft line. The elastic supports model the stern shaft bearing and the entire shaft line. It is noted that the antifriction materials used for shaft bearings can be metallic or non-metallic. It is pointed out that the ship's shaft line is a complex dynamic system, and the phenomenon of resonance during lateral vibrations occurs when the frequency of external excitation approaches the natural frequency of vibration of the shaft line itself. It is noted that this phenomenon is characterized by significant increases in the amplitudes of vibrations and an unstable state of the entire shaft system. This leads to serious damage and accidents of all elements and nodes of the entire propulsion complex of the vessel. The results obtained in this work in the form of graphs of the change in the natural frequency of the studied single-span beam relative to the adopted elastic boundary conditions, which characterize the entire shaft line of the shaft line, are nonlinear.