Evaluating the structural response of light ice-class ships under ice loads

In Arctic waters, ship structures are exposed to various forces, including ice impact loads. Assessing structural capabilities is crucial for understanding the hull's capacity and ensuring the safety of vessels, crews, and the environment. The capacity of ship structures represents a limit at which vessels can be operated without surpassing safe boundaries, thereby avoiding damage. This paper demonstrates a methodology for characterizing the structural responses to a range of ice load magnitudes for the purposes of providing feedback to mariners. The approach uses the bow grillage panel of a low Polar Class ship as an example in compliance with the International Association of Classification Societies Polar Class rules. The ice-crushing forces are estimated using a combination of the Popov model and the pressure-area curves method for the specified light ice conditions and ship-ice contact geometry. Then, the behavior of the hull is examined by applying the design load and a progressive series of ice loads to the middle of the panel. Finite Element Analysis is implemented to develop a look-up table outlining the structural response for each ice force and demonstrating limits corresponding to the structure's design and repair-required levels. The look-up table enables a comparison to thresholds corresponding to the structure's design and repair-required limits. The practical implications of this study are intended to provide advice for ship operators to enhance the safety of light Polar Class ship structures when navigating in ice-covered waters.