Shared-energy prediction model for ship-ice interactions

Abstract

To model the structural response of low- and non-ice-class ships requires both the ice and structural responses to be accounted for. A weakly coupled shared-energy algorithm is presented to model a ship-ice interaction for low- and non-ice-class ships. The algorithm is created to model the ship response within the operational design limits of the International Association of Classification Societies (IACS) Polar class rules [1], and therefore, employs many similar assumptions and methods as the IACS Polar rules. First, the Popov collision model [2] is implemented to determine the initial kinetic energy of the system. Daley’s energy based ice collision force models [3] are adopted, assuming a pressure-area relationship, to determine the ice-crushing energy. The structural deformation energy is determined by superimposing the frame and plate response. The flexural strain energy of the beam is derived from classical beam theory. The plate deflection energy is modelled with a meta-model created through experiments conducted with finite element analyses and the design of experiments methodology. The algorithm determines the energy distribution through a system of equations that iterates the shared contact force until the internal energy of the system (the ice and structural response) equals the initial kinetic energy of the interaction. Various finite element benchmarking analyses are conducted to assess the prediction capabilities of the individual structural models, the combined structural response, and the algorithm as a whole.