Ice loads in ship-ice glancing impacts: Experimental investigation and validation of energy-based predictions

Arctic shipping has grown significantly in recent years, driven by diminishing sea ice and the pursuit of shorter shipping routes. However, the harsh Arctic environment poses risks to ships, particularly from ship-ice collisions, which can damage hulls and threaten safety. Accurate prediction of ice loads during such interactions is crucial for designing ice-going vessels. This study investigates ice loads induced by glancing impacts between a ship and a free-floating ice floe through a series of model-scale experiments conducted in calm water. A novel model ice material with stable compressive strength at room temperature was developed to ensure consistent test conditions. The experiments measured ice loads, ice indentation, and the motions of both the ship and ice models during impact. The results were compared with predictions from the energy-based Popov method, which evaluates ice loads using momentum and energy conservation principles. The study found that the Popov method provides reasonable predictions of ice loads, particularly in capturing the influence of ship speed, but tends to underestimate the measured loads. The contact location between the ship and ice floe has a significant influence on the magnitude of ice loads, with impacts near the bow shoulder generating higher forces compared to those closer to the stem. While the Popov method can qualitatively reflect the influence of contact location on ice loads, it significantly underestimates the strength of this effect. Visual observations suggest that the variation could be attributed to the ship-ice hydrodynamic interaction, which may not be captured by the Popov method. The findings highlight the importance of considering contact location and hydrodynamic effects in ice load predictions. In contrast, the Popov method overestimates ice indentation by assuming that all kinetic energy loss is absorbed by the ice failure, disregarding other energy dissipation mechanisms. This research contributes to the validation and refinement of theoretical models for ship-ice interactions, offering insights into the design of ice-going vessels operating in Arctic conditions. • First model-scale glancing ship-ice collision tests with both ship and ice free to move in 6 DOF. • New beeswax-based model ice with stable compressive strength and deformation retention, enabling repeatable collisions. • Demonstrated Popov method can predict ice loads, though with underestimation in loads and overestimation in indentation. • Observed ship-ice hydrodynamic interaction can affect motions of ice and ship, consequently altering ice loads. • Results inform ice-going ship design and show ice load models need refinements to include hydrodynamic effects.