Determination of Life Cycle and Torsional Vibrational Stress for Marine Propeller Shaft

Abstract

The project deals with the determination of life cycle and torsional vibrational stresses of a marine propeller shaft for a Research Vessel. In order to withstand the torsional and internal stresses, the material used for the propeller shaft is CK45 steel with an engine power of 18560KW. The shaft runs at a speed of 160 rpm. Presently the shaft used is a solid shaft. We have done the analysis for the shaft under cold static in closed flange condition, whose construction should be efficient to produce the required amount of torque. The main aspects calculated to achieve this are inner and outer diameter of propeller shaft, bending stresses, bending moments at various parts of the shaft such as aft, intermediate stern, forward and also at the bearings. Considering the necessary parameters, the design and alignment of the marine shaft has been done in such a way that the shaft can resist the stresses induced, and avoid the deflections produced by the bending moments. Various calculations such as torsional vibrations, diameters based on low and high cycle criterion are based on formulae obtained from a set of marine shafting rules called IRS (Indian Register of Shipping).Shafting analysis is done to find various parameters like forces and bending moments at various parts of the shaft using a software called Nauticus Shaft alignment software by class regulatory DNV. This analysis has been compared with the analysis done in ANSYS and the results have been well matched with the existing values.