Abstract
Glacial ice features pose great threats on the safety of ships and offshore structures in the arctic. House sized bergy bits or growlers are of particular concern because of the detection capability limits of marine radars. Analysis and design of structures against collisions from such glacial ice bodies has always been challenging due to the complicated hydrodynamic-ice-structure interaction.This paper proposes a numerical solver for coupled simulation of glacial ice impacts accounting for the effects of hydrodynamic-ice-structure interaction. The solver adopts user subroutines provided in LS-DYNA and combines three different modules, i.e. the BWH (Bressan-Williams-Hill) criterion for the prediction of fracture of steels, a hydrostatic pressure dependent plasticity-based material model for constitutive modelling of ice, and the linear potential flow theory for hydrodynamic loads.The proposed solver is verified and calibrated to ice resistance data from field tests and is then applied to simulate ice collisions on a semi-submersible platform column. Collision scenarios with both in-plane 3DOF and full 6DOF ice motions are considered. The results are discussed with respect to ice motion trajectories, ice crushing and structural damage under the combined action of ice indentation and sliding loads. The dissipated energy predicted by external dynamic models is compared with simulation results and discussed.
Highlights
Human activities increase continuously in the Arctic regions related to exploration and production of natural resources and maritime shipping
Analysis and design of ships and offshore structures against glacial ice impacts is challenging with multiple interaction effects, including hydrodynamic loads, ice mechanics and structural mechanics
This paper presents a numerical solver for coupled simulation of glacial ice impacts accounting for hydrodynamic-ice-structure in teractions
Summary
Human activities increase continuously in the Arctic regions related to exploration and production of natural resources (e.g. oil and gas) and maritime shipping. Analysis and design of ships and offshore structures against glacial ice impacts is challenging with multiple interaction effects, including hydrodynamic loads, ice mechanics and structural mechanics. The decoupled method generally works for head-on collisions, which are often considered as the worst condi tion This includes only the indentation type of structural damage. Proper hydrodynamic modelling is essential to understand the evo lution of hydrodynamic loads during collision, the effect of ice motions, and the influence of combined ice indentation and sliding on the structural damage. An example of CFD simulations with application to ice can be found in Huang et al (2020) using STAR-CCM to calculate ship resistance operating in level ice. CFD simulations, on the other hand, require significant modelling efforts and computational resources, especially when very large fluid domains are involved. Ice density (Kg/m3) Young’s Modulus (GPa) Poisson Ratio Ice friction Material coefficient a0 (MPa2) Material coefficient a1 (MPa) Material coefficient a2 (− )
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