The Direct Calculation And Analysis For The Strength Of A40m Steel Passenger Catamaran

The passenger catamaran, as a new type of Marine traffic tool, plays a more and moreimportant role in the passenger transportation industry in China. Generally, a passengercatamaran has many advantages such as small wave resistance, high speed, large deck area andgood stability. However, because of the different ship types, there is a big difference in the loadand the strength on the structure between the catamaran and the single hull ship when navigatingunder various conditions. It is subjected to not only the longitudinal bending moment, but alsothe huge transverse bending moment and torque moment on the cross-structures. In order toguarantee that enough strength of the hull to resist a variety of external forces, checking thestrength of a catamaran sailing under various conditions is essential. Besides, using steel hullwill virtually increase the weight of the hull. For the steel passenger catamaran, which aims toincrease the capacity and improve the economic benefit, guaranteeing the hull strength whentrying to reduce the hull weight is one of the emphases in the design stage. So，during thestructure design stage of the steel catamaran, how to adopt an appropriate method to accuratelyanalyze the hull strength, and to have an optimization design of the hull structure according tothe analysis results are very important research topics.In this paper, the finite element analysis is conducted to check the structure of the40m steelcatamaran so the structure design is optimized. The contents are as follows:(1) Structure calculation of the hull according to the specification. Based on the givenformula, the wave impact pressure in specific areas of the catamaran as well as the structure sizeunder the pressure with the unit of compartment was calculated. Meanwhile, the cross structureswere strengthened in the form of transverse-longitudinal division plate.(2) The finite element analysis of the catamaran. The finite-element model was establishedaccording to the structure sizes calculated. Then the hull structure was analyzed with the FEMsoftware MSC.Patran/Nastran to obtain the stresses and their distribution on the components,with the boundary conditions set and the load imposed under the common conditions. Based onthe results, it is safe to conclude that the stress level is so low that the gap between maximumand allowable values is large, which shows that the component sizes are too large or the layoutis not reasonable. So the structure optimization has certain necessity.(3) Optimization of the Structure and the analysis. The structure of the catamaran wasoptimized according to the results of the finite element analysis, and the component sizes and the arrangement were gradually adjusted so as to reduce the weight of the ship. Based on the finiteelement analysis results of the optimized body, the strength met the specification requirementsand the weight of the hull reached a lower level. In conclusion, the optimized ship could achievethe purpose of improving the ship navigation performance and increasing the operationaleffectiveness. In this way, the rationality optimization was also validated.In this paper, the analysis methods, process and calculation results have a certain referencevalue for strength calculation and optimization of the similar ship.