EXPERIMENTAL STUDY OF THE PARAMETRIC OSCILLATIONS OF SHIP SHAFTING
The paper considers the issue of parametric oscillations of ship shafting. It is noted that the result of wear of the stern tube bearing is the loss of the working capacity of the whole ship. The lower values of the natural frequency in the transverse oscillations with increasing gap in the stern device are shown. The possibility of the shaft breaking away if the bearing wear is high is stated. The conclusion is that the range of the breaking away depends on the rate of wear. As a specified example, the case of breaking away of the propeller shaft from the aft stern tube bearing in the transverse oscillations is considered. The designed experimental installation and the measuring system for the study of the mechanical displacements of the beam are described. It is stated that if the frequencies of the forced and natural oscillations coincide the amplitude of the system oscillations is maximum, therefore, the maximum range of the amplitude corresponds to the resonant frequency. During the tests, while using the experimental installation of the transverse oscillations of the beam in subresonance and resonance zones the breaking away of the beam from the sleeve was observed. The indication of the oscilloscope and the waveform of the voltage over time for the oscillations of the beam on point and extended supports are shown. The increase in the intensity of isolation while increasing the clearance between the sleeve and the beam, and the difference of the values of the natural frequencies of the beam on the long leg from the values of the frequency on the point support are demonstrated.