Reduced Multibody System Transfer Matrix Method for Ship System Vibration Modeling

The vibration performance of a ship such as maneuverability, comfort and reliability depends on the advanced dynamics design ability of ship system. A ship can be considered as a multi-rigid-flexible-body system composed of a large number of rigid bodies and flexible bodies. Its dynamics design ability is reliant on the advanced ship system dynamic theory. As a rather novel dynamics method for multibody systems, the Multibody System Transfer Matrix Method (MSTMM) has been developed in the past 30 years. Compared with ordinary dynamics methods, it has the advantages of low order of system matrix and independence of system degrees of freedom (DOF), fast computational speed and high programmability. It has been widely used to solve more than 150 engineering problems around the world. In particular, the Reduced Multibody System Transfer Matrix Method (RMSTMM) not only retains all the advantages of MSTMM, but also benefits from the high computational stability. In this paper, the multi-rigid-flexible-body system dynamics model of the ship system including a propeller subsystem, rotating shaft-hull subsystems, bearing seat subsystems, shaft-coupling subsystems and motor subsystem, and transfer equations as well as reduced transfer equations with recursive forms for the ship system and its elements, such as, rotating Timoshenko beam, rotating rigid cylinder, are developed for the first time by utilizing the RMSTMM. Consequently, the efficient modeling and simulation of the ship system dynamics and eigenfrequency are achieved.