Numerical Study of Load Resolution Effects on Icebreaker Structural Response

To provide reliable evaluation of structure safety, it is essential to investigate the influences of ice load distribution on the structural response. In this paper, numerical simulation was carried out on a typical bow structure of an icebreaker under non-uniform loads. To obtain the ice load distribution, the Discrete Element Method (DEM) was employed under the scenario of the Xuelong 2 icebreaker advancing at 2 knots in 2 m thick level ice. Based on the results, ice load distribution models with various spatial resolutions were established for structural analysis. To study the structural response, the Finite Element Method (FEM) was applied to a bow structure composed of frames, plates, and stiffeners. The results demonstrate that the structural response exhibits significant dependence on the load resolution. For Event 1, the maximum von Mises stress rises with resolution up to a subzone width of about 600 mm (12 subzones, i.e., 1.5 frame spacings) and changes more gradually thereafter. This behavior can be attributed to the fact that the subzone number governs the characteristic dimension of local loading zones. Finer subzones better preserve local pressure concentrations and their positions relative to the frames. At Position A and a resultant of 350 kN, uniform loading over the same footprint underestimates the peak von Mises stress, principal strain and displacement by 55%, 46% and 27%, respectively, relative to the 48-subzone field. The results for Events 2–4 indicate that these load distributions may require a greater number of subzones than Event 1. Because coarsening preserves the resultant and the loaded area, the response differences reported here are attributable to the spatial resolution of the pressure field alone. The results provide a quantitative basis for selecting load resolution in local structural assessment. However, these findings are based on a single bow configuration and four DEM events and have not yet been experimentally validated.