To address the issue of fatigue damage to propeller blades caused by ice impact, this study proposes a global rapid prediction method for blade fatigue strength during the ice-propeller milling process.

A numerical model of ice-propeller milling interaction was established using a PD−FEM coupling algorithm. By integrating a fatigue strength evaluation method based on a modified S−N curve and Miner's linear cumulative damage theory, a reasonable and feasible fatigue strength prediction method was developed for propellers operating under dynamic ice contact loads in ice-covered waters. The algorithm was accelerated using the Python-based parallel computing architecture, enabling the visualization of the three-dimensional fatigue damage contours of the propellers under dynamic ice loading.

It was found that under the milling conditions, fatigue stress on the blade surface was mainly concentrated near the trailing edge at approximately 0.1R, while the fatigue stress on the blade back was mainly concentrated near the leading edge at approximately 0.3R, the mid-chord region of the blade root and the blade tip region. In addition, even at the same position, different blades exhibited varying stress levels and amplitudes due to differences in the magnitude of ice loads, leading to significant differences in the fatigue performance of different blades during ice milling.

The results show that the proposed fatigue strength prediction method can effectively assess the fatigue life of ice-area propellers under complex operating conditions, and provide strong theoretical support for the design and optimization of propellers used in ice-area vessels.

This study seeks to predict the hydrodynamic properties of composite propellers and analyze their fluid-structure interaction characteristics.

Combined with the boundary element method (BEM) and finite element method (FEM), a composite propeller fluid-structure interaction calculation method is established. The surface pressure and hydrodynamic force of the composite propeller blade are calculated by BEM, and the calculated surface pressure of the propeller is transferred to a finite element structure model. The displacement and stress distribution of the composite propeller under load are then predicted by FEM, and the deformation is transferred to the hydraulic force calculation of the propeller BEM so as to realize two-way fluid-structure interaction calculation. The feasibility of this method is verified by calculating a 5471 propeller and comparing it with the experimental values in the literature, then comparing and analyzing the hydrodynamic performance of the 5471 composite propeller and a rigid propeller.

The results show that the proposed method can realize the hydrodynamic performance analysis of composite propellers, which has the advantages of simple implementation, high calculation efficiency and high accuracy.

The findings of this study can provide reliable data support for the adaptive design of composite propellers and improve their design efficiency.

The toroidal propeller can effectively reduce tip vortex leakage due to its unique shape, which is beneficial for reducing hydrodynamic noise and improving propulsion efficiency. However, its complex shape also makes it challenging to model its geometric shape using conventional mathematical expression methods. Therefore, it is necessary to study the mathematical expression of the toroidal propeller.

First, the structural characteristics and advantages of the toroidal propeller are introduced in detail. Next, by referring to the mathematical expression of conventional propeller geometry, geometric parameters such as axis span, lateral angle, roll angle and vertical angle are introduced, and a detailed 3D coordinate formula for the toroidal propeller is derived by distributing the geometric parameters in the axis span direction, thereby establishing the mathematical expression method for toroidal propellers. Finally, taking the offset of a certain toroidal propeller as an example, the feasibility of the proposed mathematical expression method for toroidal propellers is verified.

The results show that the proposed method can smoothly establish the geometric shape of a toroidal propeller.

The proposed method can facilitate the rapid 3D modeling of toroidal propellers, laying a solid foundation for further research on the physical characteristics and scientific problems associated with toroidal propellers.