Research On The Structure Of Positive Separating Bulbous Bow

Bulbous bow can effectively reduce the wave-making resistance, especially forhigh-speed vessels (such as container ship and cruise ship). For such kinds of shipswith high speed, the wave-making resistance is usually the domain resistance of allthe resistance components, installation of a long bulbous bow can help to decrease thewave-making resistance significantly. However, vessels with high speed run a lot ofcollision risk, and a long bulbous bow worsens the outcomes of a collision accident.The reason is that the long bulbous bow may puncture the struck vessel’s hull, whichcould result in the leakage of fuel oil or even dangerous goods, thus bring aboutserious environmental disasters. In this paper, the bulbous bow (especially longbulbous bow)-side hull structure collision scenario has been investigated deeply inorder to find feasible anti-ship collision methods.The major works and conclusion in this paper were listed as follows:1) Based on the photos from3different real collision accidents, this paperpointed out that the struck vessel usually had a forward velocity and a more real shipcollision scenario should assume that the struck vessel had certain speed. Themechanical and structure deformation behaviors of the bulbous bow had beeninvestigated under that kind of collision circumstance.2) By Considering the structure configuration of a typical bulbous bow, aanti-ship collision method based on the buckling failure of high tensile steel plate anda anti-ship collision method based on the brittle fracture failure of high tensile steelplate were proposed.3) Based on the results of Dr.ZhangLeShan’s experiment researches, materialmodels and failure criteria for mild steel and high tensile steels used in this paper hadbeen determined. The results of tensile tests simulation showed that material modelsused in this paper could reflect the fracture toughness of the respective materials.4) The finite element analysis software POSEIDON from Germanischer Lloydand ANSYS software were jointly used to model the finite element collision model. A4000TEU container vessel had been modeled in detail with all the holes andstiffeners. Nonlinear finite element analysis software LS_DYNA was used to studythe behavior of a conventional bulbous bow during collision. Bulbous bow’smechanical characteristics and deformation characteristics had been investigated,which would provide the basis for the design of the novel positive separating bulbousbow. 5) Nonlinear finite element analysis software was use to study the proposedmethod based on the buckling failure of high tensile steel plate and the proposedmethod based on the brittle fracture failure of high tensile steel plate. Bulbous bow’smechanical characteristics and deformation characteristics had been determined. Theresults showed that the proposed positive separating bulbous bow could keep intact innormal working condition and rupture in critical collision condition, which confirmedthat the proposed bulbous bow could meet the design requirements and the methodwas feasible. Base on the finite element analysis results of buckling failure method,the author suggested making holes on the platforms or on the decks in areas near thestrip of high tensile steel plate to ensure the high tensile steel plate could deform andbuckle more freely under compression.