Extrusion between the side structure and the level ice is one of the most common scenarios encountered by polar ships. It is of great significance for the design and operation of polar ships to explore the mechanism of the extrusion between the level ice and the broadside. A numerical simulation model of the interaction between the level ice and the broadside is established by using the discrete element method in the current study. The rationality of the numerical model is verified based on the results of a model test on the ice loads during the broadside extrusion conducted in an indoor ice tank. The influence of the variation of the angle between the level ice drift direction and the ship's heading on the ice loads during the broadside extrusion is studied and analyzed based on established numerical model of the extrusion between the level ice and the broadside. The mechanism of the broadside extrusion and the distribution law of nonlinear ice loads are discussed. It can provide technical support for predicting ice loads and structural responses in the scenario involving the extrusion between the level ice and the broadside.

Lightweight technology is an important development trend of ships. Lightweight hull structure design may lead to novel designs that break through existing standards, including new structures or new materials. Based on an overview of the existing safety assessment system for ship structures, it focuses on the safety assessment process and methods for the lightweight structural design, including alternative design process, novelty evaluation indicators and approaches, and methods for determining structural safety assessment criteria based on limit states. The proposed novelty evaluation and safety assessment methods for the lightweight structural design are then applied for practical analysis of the typical cases of the lightweight structural design for oil tankers, bulk carriers, and container ships from literatures published at home. The proposed novelty evaluation and safety assessment methods for lightweight structural design can provide approaches and methods for the structural safety assessment of the corresponding new or alternative designs.

Oil and gas explosion is one of the main risks of offshore platforms. Structural design based on explosion risks is the development trend of the design technology. The technical regulations and specifications related to risk analysis are reviewed to summarize the procedures for the assessment of the blast risk, and the method and procedures for the assessment of the blast-resistant performance of the structure. The screening analysis, strength level analysis, plasticity level analysis and performance assessment are carried out to complete the risk-based assessment of the structural performance design for the accommodation of a FPSO offshore platform by using the structural finite element analysis software. The structural designs under different blast risk levels are performed based on three performance levels of function, operation, and life safety, designing out a scheme that meets the criteria of each performance level.

Stabilizing systems are necessary for the ship in wind and waves to ensure stable operations and improve the safety and comfort of the crew.As an effective stabilizer, gyrostabilizer acts entirely within the hull without requiring sufficient movable weight to generate a control moment. The nonlinear wave force disturbance model of the ship in random waves is firstly established. The combined dynamic model of the ship and the gyrostabilizer is then built together with the working principle of the gyrostabilizer. The corresponding MATLAB Simulink block diagramsof the ship motion control are constructed for two kinds of gyrostabilizer models, i.e., the natural-driven gyrostabilizer model and the controller-driven gyrostabilizer model. The results show that both the natural-driven and controller-driven gyrostabilizer are able to reduce the rolling motion through the gyroscopic effect of high-speed spinning and precession angel variation. The controller-driven gyrostabilizer can reduce the nonlinear rolling motion of the ship more effectively than the natural-driven gyrostabilizer.