Collision Simulation & Research Of Double-hull Oil Ship Of The Three Gorges Reservoir Area

With the usage of the Three Gorges reservoir area of the Yangtze River, the number of ship in the reservoir area increases rapidly, and the possibility of collision accident will increase. Ship collision can always make some disasters, including structure damage, environment pollution and casualties. Therefore, to improve the anti-collision of ship is of great importance, no matter what consider safety, economy and protecting environment.Because of the own huge mass and kinetic energy ,the structure of collided area will exceed elastic phase rapidly, then turn into the plastic flow status, meanwhile, damage and failure such as fracture and bulking could happen. Unlike the collision of the land structure, the fluid around the ship is also involved in the absorption of energy, which will affect the process and results of the collision. In the course of collision, the structural failure and the ship movement happen at the same time, and it should be combined to solve because they are interactive.To study ship collision, generally, mechanical mechanism is divided into external and internal collision mechanics, many methods have been developed for internal collision mechanics, including empirical method, simplified analytical method, experimental method and finite element method(FEM). Among these, the finite element method numerical simulation is one of the most effective ways, including the fluid - solid coupling method, added mass method and the equivalent hull beam method. Fluid - solid coupling technology could be solved the interaction between the hull and water, which is the most accurate method of calculation, but spent a lot of computer time; Added mass method will be thought the affect of the fluid around the ship as the form of added mass, and it can significantly improve the efficiency of the calculation, but it is still heavy task of modeling the whole hull; The equivalent hull beam method build the structure of the directly collision region by a detailed finite element model, the other regions by the beam with the corresponding mass distribution and bending stiffness, and then linked up the two parts appropriately. The fluid around the hull is thought as the form of added mass, this method will greatly enhance the efficiency of modeling and simulation speed.First, this paper discusses the basic theories about the non-linear finite element technology, such as Lagrange and Euler unit, hourglass control, explicit time integration, the dynamic properties of materials and contact problems. Second, the equivalent hull beam method is used to build the collision model of the hull by the finite element simulation software MSC.Patran and MSC.Dytran. In this course, many methods are introduced, for example, the distribution of the mass, the mesh size, element type, material model and the group of model. On this basis, the finite element model of side collision of ship was built to study the side structures collision characteristics. By the research of collision simulations, we obtain the pictures about damage distortion depend time and the curve of relative between energy and penetration, collision force and penetration. The paper discusses the influence of different mass, initial velocity and collision position to the characteristics of ship side structure in collision, and then gets the general conclusion of the characteristics of ship side structure in collision.