Deformation Mechanics Analysis Of Ship Collision And Grounding And Ultimate Strength Prediction

With the rapid development of shipping industry,the number of ships that sail in heavy traffic lanes is increasing,therefore,the possibility of collision between ships and ships grounding over seabed obstacles has become progressively higher,which threats the safety of ships and other marine structures seriously.During the ship collision and grounding accidents,the plastic deformation and even rupture of ship side structures or bottom structures occur for resisting the impact of the external load,which may lead to earlier penetration,oil leakage and decrease of the hull girder strength,and result in economic loss,severe environmental pollution,and loss of human lives.Therefore,it is of great importance to rapidly and accurately predict the crashworthiness of ship in the design phase.The shape and size of the bow or seabed obstruction significantly affect the characteristics of damage.This paper uses mainly the simplified analytical methods and nonlinear finite element simulation methods to analyze the deformation mechanisms of four basic ship collision and grounding accidents.The main work includes:1.For the accidents that ship subjects to raked bow collision,the resistance expressions of outer side plate and stiffeners attached on the side plate and deck are proposed,the crushing and tearing resistance expressions of deck and side girders are integrated to analyzing the structural response of the whole side structure,and the results are verified using numerical simulations;2.For the accidents that ship subjects to bulbous bow collision,the resistance expressions of outer side plate and its stiffeners are proposed,the tearing resistance expression of outer side plate and the crushing and tearing resistance expressions of side girders are integrated to analyzing the structural response of the whole side structure,and the results are verified using numerical simulations;3.For the accidents that ship runs grounding over shoal-type seabed obstructions,the energy dissipation expressions of outer bottom plate,bottom longitudinal girders,bottom transverse frames and the stiffeners attached on these three plating structures are integrated to analyzing the structural response of the whole bottom,and the results are verified using numerical simulations;4.For the accidents that ship runs grounding over rock-type seabed obstructions,the resistance expression of bottom transverse frames is proposed and the tearing resistance of outer bottom plate is integrated to analyzing the structural response of the whole bottom,and the results are verified using numerical simulations;5.Then,the improved Smith’s method is used to predict the residual ultimate strength of a ship after these four type accidents happened,and the results are verified using the nonlinear finite element method.Results and conclusions in this paper may benefit the assessment of s ship’s crashworthiness during its structural design phase and rapid risk assessment for dangerous grounding and collision scenarios.