Yukui Tian

The crushing failure of sea ice is a critical design issue for polar offshore structures and ship structures because ice-induced loads may generate pronounced local damage and dynamic responses. Accurately modelling this process remains challenging because ice crushing involves localized fragmentation, crack propagation, rubble accumulation, and repeated contact release. This paper presents a controlled numerical sensitivity study of level-ice crushing against a vertical structure using a coupled LS-DYNA framework that combines the Structured Arbitrary Lagrangian–Eulerian (S-ALE) formulation with the Cohesive Element Method (CEM). The study focuses on a benchmark-scale indentation configuration and examines how mesh topology, mesh size, and imposed indentation velocity affect the predicted fracture morphology and load-time histories. The results show that random triangular meshes better reproduce stochastic fragmentation and lateral flaking than regular triangular or quadrilateral meshes, while finer meshes reduce excessive load oscillations and provide more stable force histories. The velocity study indicates a transition from gradual crushing and fragment retention at lower velocities to more rapid brittle chipping and stronger dynamic fluctuations at higher velocities. A benchmark-level comparison with published ice-indentation simulations shows that the predicted peak line load is of the same order of magnitude as reference results. The proposed framework is therefore useful for investigating numerical sensitivities and failure-mode trends in ice-crushing simulations, although final design-load application requires further calibration and formal mesh-independence assessment.

Ice accretion on arctic vessels and offshore platforms poses serious threats to navigation and operational safety. Existing research has primarily focused on isolated structures. This study employs a combined approach of numerical simulation and experimental validation. It systematically investigates the icing characteristics of tandem twin-cylinders in wake flow fields. This configuration is common yet rarely studied in real marine environments. The model employs two identical cylinders arranged in tandem. It examines the effects of wind speed, distance, diameter, and wind direction angle on ice accretion morphology and distribution. Validation was conducted through wind tunnel tests at 5 m/s wind speed and 2.0 g/m³ liquid water content. Results demonstrate a significant shielding effect from the upstream cylinder wake. As wind speed increases, the ice mass difference between upstream and downstream cylinders widens. Ice mass shows a nonlinear relationship with distance. Minimum ice accretion on the downstream cylinder occurs at 350–450 mm distance. This results from wake pattern transition. The shielding effect exhibits strong nonlinear dependence on wind direction angle. A deviation of 8.2° increases total ice mass by 242.5%. Multivariable analysis confirms these nonlinear mechanisms persist under coupled distance–wind speed variations. This study provides the first systematic revelation of twin-cylinder icing mechanisms in wake flow fields. It offers a validated predictive tool for anti-icing design of arctic marine structures.

Wave propagation is impacted by the presence of ice floes. The influence of waves, on the other hand, causes ice floes to overlap and accumulate. In this paper, the interaction of ice floes and regular waves was simulated using the Finite Element Method. Firstly, natural ice floe fields were generated using the Python 3.10 programing language, with floe size distribution and randomness taken into consideration. Then, using the velocity inlet boundary wave generation method, regular simple harmonic waves were produced. The process where ice floes couple with waves was simulated with the Coupled Eulerian–Lagrangian (CEL) approach. Variations in wave height after passing through the ice floe field were investigated, and further research was conducted on the movement and fragmentation characteristics of ice floes. Simulations employing the Coupled Eulerian–Lagrangian (CEL) approach reveal that (1) ice floe motion exhibits periodic characteristics synchronized with incident wave periods; (2) wave height attenuation increases by 62–80% with rising ice concentration (70–90%); and (3) fragmentation predominantly occurs at wave trough phases due to flexural stress concentration. These findings quantitatively characterize wave–ice energy transfer mechanisms critical for polar navigation safety assessments.

During icebreaker navigation in ice-covered waters, icebreaking resistance and dynamic ice loads acting on the bow critically determine the vessel’s icebreaking performance. Quantitative characterization of the icebreaking resistance behavior and ice load distribution on the bow is essential for elucidating ship-ice interaction mechanisms, assessing icebreaking capability, and optimizing structural design. This study conducted comparative icebreaking tests on two icebreaker bow models with distinct geometries in the small ice model basin of China Ship Scientific Research Center (CSSRC SIMB). Systematic measurements were performed to quantify icebreaking resistance, capture spatiotemporal ice load distributions, and document ice failure patterns under level ice conditions. The analysis reveals that bow geometry profoundly influences icebreaking efficiency: the stem angle governs the proportion of bending failure during vertical ice penetration, while the flare angle modulates circumferential failure modes along the hull-ice interface. Notably, the sunken keel configuration enhances ice clearance by mechanically expelling fractured ice blocks. Ice load distributions exhibit pronounced nonlinearity, with localized pressure concentrations and stochastic load center migration driven by ice fracture dynamics. Furthermore, icebreaking patterns—such as fractured ice dimensions and kinematic behavior during ship-ice interaction—are quantitatively correlated with the bow designs. These experimentally validated findings provide critical insights into ice-structure interaction physics, offering an empirical foundation for performance prediction and bow-form optimization in the preliminary design of icebreakers.

The properties of ice strength have a significant impact on the design and safety of structures in ice-infested waters. To analyze the flexural strength of columnar saline model ice, we conducted circular plate center loading tests at the Small Ice Model Basin of the China Ship Scientific Research Center (CSSRC SIMB) in China. The tests involved varying the loading rate and ice temperature, and a numerical model was developed using FEM and LS-DYNA for validation and comparison. The results of the tests revealed the crack propagation process, stress distribution, load response, and failure mode of the model ice. The model ice displayed typical brittle failure, and the flexural strength was linearly related to ice temperature but not significantly correlated with loading rate. The porosity of the model ice affected the load response and time of failure but not the failure mode. The model ice with 7% porosity had a 7.8% reduction in load response compared to the nonporous model ice. This study provides a reliable method for measuring and analyzing the flexural strength of model ice. It also serves as a foundation for further research on the interaction between structures and ice sheets.

The determination of ice loads on polar vessels and offshore structures is important for ice-resistant design, safe operation, and management of structural integrity in ice-infested waters. Physical model testing carried out in an ice tank/basin is usually an important technical approach for evaluating the ice loads. However, the high cost and time consumption make it difficult to perform multiple repetitions or numerous trials. Recently, the rapid development of high-performance computation techniques provides a usable alternative where the numerical methods represented by the discrete element method (DEM) have made remarkable contributions to the ice load predictions. Based on DEM simulations validated by physical model tests, numerical ice tanks can be developed as an effective complement to their counterparts. In this paper, a numerical ice tank based on 3D spherical DEM was established with respect to the small ice model basin of China Ship Scientific Research Center (CSSRC-SIMB). Based on spherical DEM with parallel bond model, the model tests of typical structures (vertical cylinder and inclined plate) in level ice sheets were established in the numerical ice tank, and the ice–structure interaction process under the same initial conditions was simulated. The accuracy of the simulations is verified by comparing the simulated ice loads with the measured ice loads from the model tests in the CSSRC-SIMB. Furthermore, the application of the numerical ice tank was extended to simulate the navigation of a Wass bow in level ice and broken ice conditions. The value of the break resistance of the Wass bow in level ice was evaluated, and the numerical ice tank produced results that were found to be consistent with those obtained from Lindqvist’s formula. The statistical properties of the bow load for different broken ice fields with the same initial physical conditions are analyzed by performing a repeatability test on the broken ice fields.