The Direct Calculation Method Of Catamaran Structure Strength

The design of ship structure usually depends on two methods: criterion design and direct calculation. For the increase of ship size and the development of new ship type, every classification society in the world is searching for reasonable and reliable new design method. Then ship structural direct calculation method is used more widely than before. Because of its excellence: broad deck, stable navigation, flexible manipulation and so on, catamaran is becoming more and more popular. There are several instances prescribed by Chapter 15--catamaran structure supplement prescript in CCS "freshwater ship class and building criterion" which need to be calculated directly. But presently we have no concrete prescript in the field. This thesis is trying to solve this problem.With the great development in modern mechanics, computational mathematics and computer technology in hardware and software, finite element analysis has made rapid progress in both theory and computational technology. More and more general-purpose or specialized programs have been put into use, and costs on performing FEA are reduced shapely. Because complexity of ship structure and exterior carry loads, accurate forecast of construction strength is a very difficult mission. Finite element method has been one effective method in analyzing ship strength wholly and precisely. Reasonable finite element model for ship structure strength can evaluate the more exact stress state. This thesis made some primary attempts in these fields.On the whole, the author began with the actual state of catamaran research, introduced its structure character, performance, loads and strength calculation. As the most important part the cross-structure was discussed in detail. After presenting the former experience formulae, this thesis deduced a series of concise formulas and checked in three sets of ship data. Then, made use of software ANSYS to calculate the strength of a catamaran ferry structure, appliedthe formulae deduced in chapter 3, selected reasonable restraint form, in the whole ship computing result further verified the formula Then on the base of a model of the whole ship, used FEA to study the hull connecting structure with the limit of strength, deduced the useful assumption for after research. All of these, including the argumentation of formula, the ship model building, load and restraint, and so on made references to the correlative criterions.