The Analysis And Calculation Of The General Vibration Of Trimaran

It will do harm to the safe opration of ship if there are vibrations occuring during the navigation process. Therefore, in the design phase, it is very important to predict the characteristic of the ship’s vibration characteristics accurately to avoid the harmful vibration using an effective method.As a new type of ship, the trimaran has attracted more and more attention. The structure form of trimaran is more special and complex than conventional ships, thus it’s vibration characteristics is more complex inevitably. Considering the less research in the vibration characteristics of trimaran, this paper calculated the vibration characteristics of a trimaran using finite element method based on the acoustic-structural method.Firstly, the fundamental theory of the coupled acoustic-structural method in calculating wet modal was introduced. The coupled acoustic-structural method simulates the fluid medium with acoustic medium, the attached water mass can be simulated directly by building the finete element model of the outside water, which can simplify the computation process of the ship vibration problem in water.Secondly, the first4orders’ general vibrating natural frequencies of a cylindrical shell model were calculated, then compared them with the finite element calculation results which is based on coupled acoustic-structural method. The comparing result indicates that the error of the first order is within1%, and the error of the first4orders is within7%.Thirdly, the modal analysis experiment of a ship model was conducted, and the experimental result was compared with the FE calculation results. The comparing result indicates that the error of the first3orders is within10%.Lastly, the finite element wet modal analysis of a preliminarily designed high-speed trimaran was simulated using coupled acoustic-structural method, and5low orders’ general vibration types and their natural frequencies are obtained. According to the analysis result, most vibration modes of the trimaran are coupled modes, which are determined by the coupling effect of the main body and side bodies and the superstructure.