Study On Numerical Simulation Of A Lunching Ship's Dynamic Process

Ship launching, which is a very important link during the process of ship building, is a technological process moving a ship from construction site to the water after most completion of the ship's construction. The dimensions and tons of ships increase with the developing of economy and technology, so the stress between a ship and the launching facilities also increase. Thus, it requires that birth and launching facilities must have high standards. The purpose of ship launching calculation is to provide evidence for choosing launching method and facilities. Nowadays, with the maximization of ships, it's very important to predict the stress during the process of ship launching accurately.Ship launching is a complicated dynamic problem. The traditional calculation uses statics' method which regards the launching as a serial instantaneous process and view ship as a two-dimensional beam to calculate the tail floating of ship and the stress of launching way and to judge whether the phenomenon of tail bending and head dropping of ship would happen. This method was used to do estimation at the initial stage because of the rough result. The three-dimensional FEM numerical simulation method, which considers the inertia force and resistance and the underwater shape, can get velocity, acceleration and force results at any time during launching. So three-dimensional FEM is more accurate, and can be used in detailed calculation.This thesis uses three-dimensional FEM numerical simulation method and LS-DYNA fluid-structure interaction function to simulate the launching process by numerical method and the inertia force and resistance and the underwater shape should be considered. Thus, it not only predicts the stress and instantaneous speed and acceleration during the launching period accurately, but also judges the ship floating condition directly. The thesis analyses and compares the results of the numerical simulation method to traditional methods', furthermore, it verifies the feasibility and accuracy of numerical simulation and supplies significant conclusions for the launching by comparing the influence on launching process caused by different weights , friction coefficients and tide heights.The numerical simulation method will supply more accurate and direct prediction for the launching and will be the leading method with the development of computer technology and ship industrial technology.