Research On Ship-ice Collision And Simplified Analytical Method Of Stiffened Plate’s Crashworthiness

As resources of oil and gas in land dried up greatly,rich resources of oil and gas in polar have become the focus of the world’s industrial nations.In addition,with the global climate warming,permanent iceberg began to melt in the arctic regions,so routes of East Asia to Western Europe and North American can be shipping in the summer.Due to a large number of icebergs in the arctic route,collision problem may be caused in the process of resources development and polar transport,which will cause destruction of the hull structure,oil spill,life safety and irreversible ecological disaster.Research on ship collision with iceberg can give guides for design of ship structure,and provide rapid assessment of hull structure damage.Two parts are done in this thesis.The first part of the main work is that structural response of ship-iceberg collision through numerical simulations is calculated.In order to obtain accurate response of collision,a method to determine accurate end state of ship-iceberg collision is proposed,based on nonlinear finite element method and impact mechanics theory.Internal mechanics and external mechanics are combined in this method.Internal energy and dissipated energy of ship-iceberg collision are obtained through internal and external mechanics respectively.When internal energy is equal to dissipated energy,an accurate end state is got.Based on this,collision force-penetration curves,damage deformation of ship and iceberg and internal energy-penetration curves are analyzed.Then the method is applied in analysis of ship-iceberg collision with 9 different collision scenarios,including different collision locations,velocities,ice size and material models.Results show that damage deformation mainly occurs in side structural contact area with an iceberg in a strong local way.In the process of ship-iceberg collision,collision force-penetration curves appear highly nonlinear characteristics.Side shell plate and longitudinal stiffeners are the main energy-absorbing components.In the second part,research on the side components(side plate and beam)hit by a paraboloid indenter is focused.Based on plastic mechanics and simplified analytical method,simplified analytical models of side plate and beam are proposed.Then these two models are analyzed and verified by some numerical simulations and model experiments.Based on the two models,crashworthiness of stiffened plate is calculated by using the superposition principle,which superimposes stiffened plate for plate and beam structures.Results and conclusions of the paper may benefit the design of ice navigation ship’s crashworthiness during its structural design and rapid risk assessment for dangerous ship-iceberg collision scenarios.