Longitudinal Vibration Analysis of Marine Propeller Shaft Using Distributed-Lumped Modeling Technique

In this paper, the application of distributed-lumped (hybrid) modeling technique (DLMT) in the modeling of longitudinal (axial) vibration of marine shaft system is investigated. The equation of motion for the longitudinal vibration is solved in new analytical method, and modeled as a series of interconnected distributed and lumped elements. Natural frequencies of a rotor system with various elements are calculated based on the distributed lumped modeling technique (DLMT). The results obtained by this method are compared and verified with the results of other techniques, such as FEM, using ANSYS software, and the mode shapes are also presented. The method is then employed for calculating the natural frequencies of a marine propeller shaft with multiple elements such as different couplings. The results are compared and verified with the frequencies and mode shapes obtained by KissSoft software. It is shown that the presented method provides highly accurate results, while it can be simply and effectively applied to the complicated systems.