Ships navigating in ice-covered regions will inevitably collide with ice ridges.Compared to other ice bodies,ice ridges exhibit more complicated mechanical behaviors due to the scale and structure characteristics.In t...Ships navigating in ice-covered regions will inevitably collide with ice ridges.Compared to other ice bodies,ice ridges exhibit more complicated mechanical behaviors due to the scale and structure characteristics.In this paper,nonlinear finite element method is used to investigate the interaction between a polar ship and an ice ridge.The ice ridge is modelled as elastic-plastic material based on Drucker-Prager yield function,with the consideration of the influence of cohesion,friction angle and material hardening.The material model is developed in LS-DYNA and solved using semi-implicit mapping algorithm.The stress distribution of ice ridge and ship,and the ice load history are evaluated through the simulation of multiple collisions.In addition,parametric analysis is performed to investigate the influence of ridge thickness and impact velocity on the ice load and energy absorption.展开更多
The frequent change in ice drift direction poses a significant challenge for turret moored ship in ice. Variability in ice drift is mainly caused by the winds and currents. To solve this problem, a new method with num...The frequent change in ice drift direction poses a significant challenge for turret moored ship in ice. Variability in ice drift is mainly caused by the winds and currents. To solve this problem, a new method with numerical simulation based on heading control is applied to reduce the risk of operation of The Arctic Tandem Offloading Terminal(ATOT),which includes an offloading icebreaker(OIB) moored to a submerged turret and a shuttle tanker moored at the stern of the OIB in this paper. An icebreaking tanker, MT Uikku, was modeled in a simulation program. Then the level ice load on the tanker was calculated with different ice thicknesses and drift speeds, after which a heading controller assisted with mooring system is used to simulate the horizontal motion of the tanker under the ice action.展开更多
Due to complex mesoscopic and the distinct macroscopic evolution characteristics of ice,especially for its brittle-to-ductile transition in dynamic response,it is still a challenging task to build an accurate ice cons...Due to complex mesoscopic and the distinct macroscopic evolution characteristics of ice,especially for its brittle-to-ductile transition in dynamic response,it is still a challenging task to build an accurate ice constitutive model to predict ice loads during ship-ice collision.To address this,we incorporate the conventional multi-yield-surface plasticity model with the state-based peridynamics to simulate the stress and crack formation of ice under impact.Additionally,we take into account of the effects of inhomogeneous temperature distribution,strain rate,and pressure sensitivity.By doing so,we can successfully predict material failure of isotropic freshwater ice,iceberg ice,and columnar saline ice.Particularly,the proposed ice constitutive model is validated through several benchmark tests,and proved its applicability to model ice fragmentation under impacts,including drop tower tests and ballistic problems.Our results show that the proposed approach provides good computational performance to simulate ship-ice collision.展开更多
文摘Ships navigating in ice-covered regions will inevitably collide with ice ridges.Compared to other ice bodies,ice ridges exhibit more complicated mechanical behaviors due to the scale and structure characteristics.In this paper,nonlinear finite element method is used to investigate the interaction between a polar ship and an ice ridge.The ice ridge is modelled as elastic-plastic material based on Drucker-Prager yield function,with the consideration of the influence of cohesion,friction angle and material hardening.The material model is developed in LS-DYNA and solved using semi-implicit mapping algorithm.The stress distribution of ice ridge and ship,and the ice load history are evaluated through the simulation of multiple collisions.In addition,parametric analysis is performed to investigate the influence of ridge thickness and impact velocity on the ice load and energy absorption.
文摘The frequent change in ice drift direction poses a significant challenge for turret moored ship in ice. Variability in ice drift is mainly caused by the winds and currents. To solve this problem, a new method with numerical simulation based on heading control is applied to reduce the risk of operation of The Arctic Tandem Offloading Terminal(ATOT),which includes an offloading icebreaker(OIB) moored to a submerged turret and a shuttle tanker moored at the stern of the OIB in this paper. An icebreaking tanker, MT Uikku, was modeled in a simulation program. Then the level ice load on the tanker was calculated with different ice thicknesses and drift speeds, after which a heading controller assisted with mooring system is used to simulate the horizontal motion of the tanker under the ice action.
文摘Due to complex mesoscopic and the distinct macroscopic evolution characteristics of ice,especially for its brittle-to-ductile transition in dynamic response,it is still a challenging task to build an accurate ice constitutive model to predict ice loads during ship-ice collision.To address this,we incorporate the conventional multi-yield-surface plasticity model with the state-based peridynamics to simulate the stress and crack formation of ice under impact.Additionally,we take into account of the effects of inhomogeneous temperature distribution,strain rate,and pressure sensitivity.By doing so,we can successfully predict material failure of isotropic freshwater ice,iceberg ice,and columnar saline ice.Particularly,the proposed ice constitutive model is validated through several benchmark tests,and proved its applicability to model ice fragmentation under impacts,including drop tower tests and ballistic problems.Our results show that the proposed approach provides good computational performance to simulate ship-ice collision.
