INFLUENCE OF JOURNAL BEARING MODELING METHOD ON SHAFT LINE ALIGNMENT AND WHIRLING VIBRATIONS

The calculation accuracy of journal bearings stiff characteristics is one of the most important factors during static and dynamic analysis of a marine power transmission system. Especially, shaft line alignment and whirling vibration analysis are critical to proper boundary conditions determination. Today it is very difficult to find realistic data on the shaft line foundations characteristics. This paper analyzes three elements: local hull stiffness, stiffness of intermediate bearing frame, and lube oil shaft stiff characteristics. The paper discusses how several analysis of shaft line alignment and whirling vibrations of typical marine power transmission systems have been completed. Influence of different boundary conditions, modeling methods as well as shaft line operation conditions have also been analyzed.