Numerical analysis of interaction between sea ice and propeller based on coupled DEM-FEM model

Abstract

When a ship navigates through ice-covered seas, the interaction between sea ice and propellers damages the propeller blades. A coupled discrete element method (DEM)-finite element method (FEM) model was developed to investigate the interaction between an ice block and a propeller. The ice block and ice-class propeller were simulated using the sphere-based DEM and hexahedral solid elements of the FEM, respectively. According to the mechanical mechanism of the ice-blade interaction, the compressive strength of sea ice is the most important parameter for the simulation. The bonding strength between the element was determined by the element size and compressive strength of the sea ice material through uniaxial tests. Then, the ice-propeller interaction was simulated using the proposed DEM-FEM model. The convergence of the proposed numerical model was verified. For simulating the ice-propeller milling process, four parameters, i.e., carriage speed, cut depth, rotational speed, and ice strength, were investigated to analyze the ice load and dynamic response of the propeller. Finally, considering the randomness of the ice-propeller interaction with the real condition, a numerical simulation of ice-propeller interaction during backward sailing of the ship was established, and the random characteristics of the ice load on the blades were analyzed.