Research On Hull Structure Optimal Design For Standardized FRP Fishing Vessel

At present, China’s fishery equipment is relatively backward, traditional fishing boats are still the main fishery production tools, fishing boats are widely aging, and fishing boats energy consumption is quite high, all of which make fishery energy conservation work to be urgent. Fiberglass fishing boats is an kind of energy saving ship, it has many advantages, such as light weight, easy molding, corrosion resistance, long life, good economic, etc. Currently, in the United States, Japan, Taiwan, and other regions, fishing boats have all become Fiber Reinforced Plastics ones, and the energy saving effect of FRP fishing vessel is very good. However, the development of fiberglass fishing boats in China is relatively slow, and the fishing equipment level of China has been in a backward state.In China’s12th Five-Year-Plan period, China launches a specialized research, which named "Fishery Energy Saving Key Technology Research and Major Equipment Development". The purpose of the research is to vigorously promote fishery energy conservation work, accelerate the upgrading of fishery equipment, and the focus is to improve the energy-saving effect and environmental protection capacity of fishing vessels. Therefore, the promotion and standardization of fiberglass fishing boats become the main driving force of our fishery energy saving and fishery equipment upgrading.Results of structure direct calculation can timely help to modify the original design of structure, and this helps to quickly achieve the optimal design of structure. At present, there have been many detailed guides of structure direct calculation for steel ships. But because of the particularities of material, hull structure, ship form, load, etc, there is not any guide of structure direct calculation for FRP ship. Based on the above background, we studied on optimal design of hull structure for typical and standardized FRP fishing vessel. This study has a certain reference value for the direct calculation and optimal design of fiberglass fishing boats hull structure, and it helps to promote the development of fiberglass fishing boats. The main methods and contents of this paper are as follows:(1) Studied the material characteristics of fiberglass fishing boats and learned the development course of fiberglass fishing boats in various countries. We could conclude that: the key of realizing China’s fishery energy saving and fishery equipment upgrading is promoting the development and standardization of fiberglass fishing vessels. Also, discussed the research necessity and feasibility of the direct calculation and optimal design of fiberglass fishing boats hull structure.(2) Deduced the elastic constants formula of fiberglass materials. This ensures the validity of direct calculation for fiberglass structure. Studied the effects of core material and cross-sectional size on strength and stiffness of fiberglass hull cap-type girder. We could conclude that:the mechanical effect of the core material in girder is quite small, and it could be ignored in hull structure finite element models. This would make the calculation results be safer, and help to simplify modeling. And another conclusion:corresponding different girder face-plate widths, there is always an optimal range of web height value.(3) Based on the equivalence of material properties, we verified the feasibility of using the same dimensions of beam element to simulate the cap-type member of fiberglass fishing boat. Besides, we proposed a method of realizing the equivalence of fiberglass laminated beam and isotropic beam. This could provide a basis for the simplification of the finite element models of composite material structures such as fiberglass fishing boats.(4) Established the whole-ship structure finite element model of a typical fiberglass fishing vessel, and accomplished the direct calculation of the whole-ship structure. Under the allowable conditions of hull structure, by adjusting the hull scantlings gradually, making the whole-ship structure lightest, realized the optimization of fiberglass fishing boat hull structure.