Dynamic Analysis Of Ship Structural Based On ANSYS

The dynamic characteristics play an increasingly important role in modern ship design, while the hull girder model ship vibration calculation can no longer satisfy the requirements of modern engineering accuracy. The rapid development of computer enables 3D finite element analysis of a whole ship become possible. Ship’s structure is different from other engineering structures due to fluid medium which embraces the ship. Therefore it is necessary to study the effect of fluid medium on ship structure. Traditionally, the additional water mass method is employed to calculate the ship vibration problem by the assumption that the water around a ship can be treated as additional mass. In this paper, a direct fluid-solid coupling method is employed to calculate the dynamic characteristics of a 3500t oil tanker and implemented in finite element software ANSYS by using the fluid-solid interaction method based on pressure-displacement equations. The vertical and lateral distributions of reinforcement to the ship structure are analyzed to investigate the effect of reinforcements on the dynamic characteristics of the oil tanker. Numerical results showed that the dynamic characteristics of the oil tanker are significantly affected by fluid solid interaction. The dry modal frequency of bending vibration is 50% higher than that obtained by FSI analysis. The fluid-structure interaction effects also dampen the ship’s local vibration. The structural reinforcements can simultaneously improve the rigidity of ship structure and raise the vibration frequency. The reinforcements in both vertical and lateral direction of ship structure can effectively prevent its low-rank local vibration. The lateral reinforcement of ship structure is helpful to prevent the upper and lower vibration stratification for horizontal vibration of a ship.