Comparison of sphere-based and dilated-polyhedron-based discrete element methods for the analysis of ship–ice interactions in level ice

Abstract

The discrete element method (DEM) is an important approach for analyzing ship–ice interactions; however, different element shapes in the DEM may lead to different results. This study presents a comparison between sphere-based DEM (SDEM) and dilated-polyhedron-based DEM (DPDEM) for the analysis of ship–ice interactions. The parallel bonding model is used in the SDEM to simulate the breaking process of sea ice. The dilated polyhedron, which is the Minkowski sum of a sphere and a polyhedron, is used in the DPDEM. A bond-failure model that considers stiffness softening and energy release is adopted to simulate the breaking process of sea ice. The buoyant and drag forces on each element from the water are calculated, while the interactive force on the water from the element is not considered. The interaction between sea ice and a ship hull is simulated using both SDEM and DPDEM. Two ship hulls are considered, including an icebreaker and an ice-going cargo ship. The results show that the SDEM has better performance in simulating the crushing failure of sea ice. However, the ice resistances obtained with the SDEM and DPDEM are generally similar, especially the mean ice resistance. Ultimately, the computational efficiencies of these two methods are analyzed.