An elastic-plastic ice material model for ship-iceberg collision simulations

Ship-iceberg collisions are currently a hot topic of research. The modeling of iceberg material is crucial for ice mechanics, and the main objective of the present work is to propose an isotropic elastic-perfectly plastic material model to simulate the mechanical behavior of ice in a ship-iceberg collision scenario for Accidental Limit State conditions. The 'Tsai-Wu' yield surface model and a new empirical failure criterion were used to describe the plastic flow of iceberg material, while a cutting-plane algorithm was adopted to address the plastic stress-strain relationship. The proposed iceberg material model was incorporated into the LS-DYNA finite element code using a user-defined subroutine. Calibration of the proposed material model was conducted through a comparison with an abnormal level ice event pressure-area curve. The calculated pressure-area curve was comparable to that recommended by the International Organization for Standardization (ISO) rule. A sensitivity analysis was then conducted, and the proposed ice model was found to be more sensitive to the mesh size than to other parameters. Numerical simulations of iceberg-tanker side and iceberg-ship bow collisions were also analyzed. Moreover, the impact force and energy dissipation were examined. The results from these simulations showed that the proposed isotropic elastic-perfectly plastic iceberg material model can be employed to simulate iceberg behavior in ship-iceberg collisions under Accidental Limit State conditions.