Structure Design And FEA Calculation For Strength Of Aluminum-FRP Composite Catamaran For Windfarm Support

With the developping of offshore wind power industry, the offshore windfarm goes further from offshore to deep sea gradually. However, here come the windfarm maintenance problems. There are not so many ships that specialized for wind power transportation maintenance in domestic. In most of the time, people will prefer renting ships to transport the technicains and maintenance to the windfarm. It is not so concenient and it will cost more money in operating. Therefore, the demand for wind- farm support vessels is becoming biger and biger. It is urgent to build such vessels to support the wind power industry. Catamaran hulls have the high speed, good stability and wave resistance, large deck area, and flexible maneuverability, which are suitable for windfarm maintenance work.This paper adopts the mother ship transformation method to a windfarm support vessel in the service of the pearl river estuary. We usually reference the similar type which is similar in performance parameters such as speed, load, and arrangement. we copy the main characteristics of the mother ship, and use AUTO-CAD to draw the new ship`s line. After that, we build the three dimensional model of the new ship with the Maxsurf, in which we can get the result of the static hydraulic calculation, stability calculation, resistance and effective power estimation etc. Besides, the layout, the rudder and the propeller will be designed.According to CCS “rules for the classification and construction of high speed ship at sea”(2015), the whole ship structure of the new catamaran designed for windfarm maintenance will be designed. Then using ANSYS WORKBENCH, the ship’s finite element model is built. The model is used to carrying on the comprehensive check, using the direct calculation method, applying the corresponding loading and boundary.This design catamaran, whose main hull is made of aluminum alloy metal material, and Superstructure is made of fiberglass composite material, has achieved innovative hull structure design. The same ship is made of aluminum alloy and steel-tight connection of glass structure, which is different from unity and limitations of traditional fiberglass or aluminum or steel shipbuilding. The main hull welded aluminum materials, effectively ensure the hull strength and stiffness, improve structural safety and crashworthiness of the ship. the ship is also easy to install large-scale mechanical and electrical equipment. Besides, the superstructure made of fiberglass composite material,can effectively reduce the weight of the construction and maintenance costs, lower center of gravity height of the ship, easy molding and meets green energy saving trend. For the ship structure strength check of aluminum & glass composite hull, there is no readily available reference specification verification method to fllow. The best way is to carry out the whole ship finite element analysis. What Key issues are as fllows: the first is the definition of the main properties of different materials of the hull and superstructure. This paper achieves the definition of the superstructure FRP sandwich composite structures with ACP module which is specifically used for the definition of composite materials in WORKBENCH. The second is the kid issues connected between different materials. Due to two completely different types of materials,it is difficult to achieve stable and high water connections and other requirements according to the general field of shipbuilding design process. Thus we use coupling node way approximate the bolt contacting relationship with the other connector.The wingfarm support catamaran designed in this paper, which is made of aluminum & fiberglass composite materials, offers innovations in hull design. The whole ship’s strength checking was analyzed with finite element analysis. And we use the fourth strength theory to analyze the connected nodes. The results show that the catamaran structure meets regulatory requirements. this is the first attempt to use a stress finite element software for the new designed composite catamaran’s stress analysis, is also an optimization for the catamaran. This paper accumulated experience for futher promote of this kind of ships and the future analysis of shiprelated design.