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An elastoplastic ice material model with a rate and pressure dependent yield criterion is proposed in the present study for ice-structure collision simulations. The yield criterion is based upon the Tsai-Wu failure envelope which is formulated in the present study to evolve with the strain rate. The relation between ice strength and loading rate is known to be disrupted at the ‘ductile-to-brittle transition’ strain rate. Hence, the yield locus evolves differently in ductile and brittle regimes, which is herein modelled using two different strain rate-strength equations. These equations, obtained from the literature, are based on more than 100 physical tests on freshwater polycrystalline ice, including iceberg ice samples. The constitutive laws, written in Fortran, are implemented in Abaqus as vectorised user material (VUMAT). The proposed material model is validated against two physical ice crushing tests with different indentation speeds, 1 mm/s and 100 mm/s.

Several alternative engineering models are available for the use in analysis of offshore wind turbines. However, it is not always clear which of the models will yield the most accurate or sufficiently conservative results. This paper investigates the effect of using two alternative soil-structure interaction models and two wind coherence models. The focus is on assessing how these modelling choices influence the predicted long-term fatigue damage in the support structure. The two soil models are a macro-element model and a p-y-curve model with Rayleigh damping. This gives differences in both the damping and stiffness properties of the turbine model. The differences between the two soil models tend to decrease as the turbine size increases. The wind coherence models considered are the Kaimal spectrum with exponential coherence and the Mann uniform shear turbulence model. The Kaimal model predicts the highest response at low frequencies, while the Mann model gives the highest response predictions at higher frequencies. Which turbulence model predicts the highest long-term fatigue damage is then determined by the natural frequencies, rotor and blade passing frequencies of the different turbines.