Numerical Study on the Effect of Buffer Bow Structure in Ship-Ship Collision

摘要

A disastrous oil spill from a struck oil tanker has become one of thernmajor problems in view of conservation of maritime environment. Sornfar double hulls (D/H) have been introduced to reduce thernconsequences of collision and grounding events In order to furtherrnreduce the oil spill from struck oil tankers, the introduction of bufferrnbulbous bows has been proposed. Relatively soft buffer bows absorbrnpart of the kinetic energy of the striking ship before penetrating therninner hull of the struck ship. The purpose of the present paper is tornverify the effectiveness of a prototype buffer bulbous bow structure inrnship-ship collisions as compared with that of standard bulbous bows.rnThis is demonstrated by conducting a series of large-scale finiternelement analyses. The finite element analyses are conducted with therngeneral-purpose nonlinear structural code “LS-DYNA”. The appliedrnscenario is one where a very large crude oil carrier (VLCC) in ballastrncondition collides with the midship region of a D/H VLCC in a ladenrncondition. Fracture of fillet welds, elastic-plastic material propertiesrnand strain rate effects, are taken into account in the simulations. Therneffect of the equivalent failure strain (FS) and the forward velocity ofrnthe struck ship on the collapse mode of the bow of the striking ship arerninvestigated. Collapse modes, contact forces and energy absorptionrncapabilities of the buffer bows are compared with those of conventionalrnbows.