The paper explores the use of a GPU-Event-Mechanics (GEM) simulation to assess local ice loads on a vessel operating in pack ice. The methodology uses an event mechanics concept implemented using massively parallel programming on a GPU enabled workstation. The simulation domain contains hundreds of discrete and interacting ice floes. A simple vessel is modeled as it navigates through the domain. Each ship-ice collision is modeled, as is every ice-ice contact. Each ship-ice collision event is logged, along with all relevant ice and ship data. Thousands of collisions are logged as the vessel transits many tens of kilometers of ice pack. The GEM methodology allows the simulations to be performed much faster than real time. The resulting impact load statistics are qualitatively evaluated and compared to published field data. The analysis provides insight into the nature of loads in pack ice. The work is part of a large research project at Memorial University called STePS2 (Sustainable Technology for Polar Ships and Structures).

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With increasing interest in resource exploitation and shipping in the Arctic, the focus on ice class ships and offshore structures is growing every year. In Arctic waters collision with ice is a major concern. The standard analytical ship-ice collision load model is based on the assumption that the ship structure is perfectly rigid body and the crushing energy of ice is equated to the available kinetic energy to calculate the ice load. This paper extends the standard approach by including the local plastic deformation. By considering the plastic work done to the structure in the balance of energy, a model is developed that can be used to help specify the levels of structural damage that may occur at various speeds. A simple unit side shell of ship structure is modeled to evaluate the absorbed energy and permanent deformation, with elasto-plastic response including linear strain hardening. A simple patch load is used. The purpose of this model is to provide a practical evaluation method of ice loads with the consideration of ship structure’s deformation. While there have been similar issues tackled numerically by several researchers, this work takes a more analytical approach, and will hopefully enable designers to more rapidly assess potential designs. Furthermore, this approach may provide a tool for regulation that is more related to actual risk levels and consequences. To illustrate the issues and practical application, the paper presents an assessment of the bow structure of a high ice class 150kT arctic tanker involved in an iceberg collision.

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