Ice Resistance Research Articles

Non-smooth discrete element method analysis of channel width's effect on ice resistance in broken ice field

A numerical model based on NDEM is used to investigate the effect of channel width on broken-ice resistance in the channel. The model incorporates a limited impulse method to simulate the ice crushing failure. The accuracy of the numerical model is benchmarked against experimental data from model tests conducted on the Araon icebreaker at KRISO. The simulations successfully capture the characteristic effects of channel width on broken-ice resistance observed in the experiment. Beyond benchmarking of the numerical model, this study analyses the force chain characteristics in the broken ice field, revealing the crucial role of force chains in the resistance increase caused by channel width constraints. Building upon the established numerical model, further sensitivity analyses are conducted to investigate the correlation between channel width effect and other relevant factors such as ice concentration, ship velocity and ice thickness. Among these factors, it is found that ice concentration emerges as the predominant determinant of the critical channel width. The increase in ice resistance attributable to the channel width is exacerbated under the condition of thicker ice floes and lower ship velocity, where the occurrence of ice floe rotation is less frequent and the corresponding force chains are stronger and more stable.

Numerical simulations of a ship sailing across pack ice area in forward motion under different drafts

Different from the existing CFD-DEM models in which the ship remains stationary, a CFD-DEM model with the ship in forward motion is proposed in this paper to simulate the process of a ship sailing across pack ice area at a forward speed under different drafts. A high-precision method for generating pack ice area on the undisturbed free surface that can be used in conjunction with the proposed model is introduced. Taking an ice-strengthened Panamax bulker as study object, the available model test results are used to verify the reliability of the proposed model, which shows that the model can effectively evaluate the resistance performance and simulate the ship-ice-water interaction. Based on the verified model, the ice resistances on different parts of the hull are first investigated, which reveals that the ice resistance of the bow is most significant, while those of the midship and stern are negligible. Then, the speed dependence of ice resistance under different drafts is studied. It shows a strong nonlinearity under shallow draft, while the nonlinearity gradually weakens as the draft increases. Finally, the proportions of ice resistance and open-water resistance in the total resistance under different drafts and ship speeds are discussed.

A CFD-DEM-FEM coupling method for the ice-induced fatigue damage assessment of ships in brash ice channels

Polar transport ships frequently traverse in the brash ice channel opened by icebreakers. Although the substantial ice resistance caused by direct collisions with the level ice is avoided, the hull still encounters collisions with the brash ice, leading to periodic damage and exacerbating the fatigue issues of the hull structure. To address the fatigue challenges faced by ships sailing in the brash ice channels, this paper proposes an ice-induced fatigue damage assessment method based on the CFD-DEM-FEM. Referring to the brash ice model test conducted at the Hamburg Ship Model Basin (HSVA), a discrete element ice model and a numerical brash ice tank are established using the CFD-DEM coupling method. The simulated ship-ice interaction is compared with HSVA’s experimental results to validate the reliability of the numerical brash ice tank and ice load. The ice load time history resulting from the ship-brash ice collision is applied to the hull, and the hot spot stress time history under each fatigue sub-condition is calculated using the FEM. The improved rain-flow counting method is employed to determine the stress level of the hot spot stress time history, and the S-N curve method based on the linear cumulative damage criterion is used to calculate the total fatigue damage of hot spots. Finally, the results of the proposed method are compared with those of the LR method. This study can serve as a valuable reference for the ice-induced fatigue assessment of ships navigating in brash ice channels.

Electrothermal-Assisted Photothermal Lubrication Surfaces for Continuous Anti-Icing/Deicing in Multiple Low-Temperature Environments.

Solving the problem of ice accumulation on solid surfaces is of great significance to the economic development of the country and the safety of people's lives. In this work, a coating with multifunctional photothermal/electrothermal solid-state lubrication (PEL) for anti-icing/deicing was prepared in layers based on the intrinsic properties of silicone oil and paraffin wax in combination with conductive graphite and multiwalled carbon nanotubes. Silicone oils and paraffins are used as lubricating media giving the coating excellent lubricity, which results in a water sliding angle (SA) of only 12° on the PEL surface. Meanwhile, PEL shows favorable static and dynamic ice resistance at low temperatures; at -10 °C, the freezing time of water droplets on the PEL surface is extended by at least 4 times compared to the bare substrate. Furthermore, PEL also offers highly efficient photothermal and electrothermal deicing performance, which can effectively remove the accumulated ice at a light intensity of 0.6 kW/m2 or an EPD of 0.1 W/cm2. Meanwhile, the synergistic deicing mechanism of photothermal and electrothermal was verified at -20 °C. Interestingly, the coating shows heat-assisted healing ability due to the phase change characteristic of paraffin wax, which allows the coating to regain lubricating properties after mechanical abrasion. Therefore, this work provides a reliable way for the design of stable all-weather anti-icing/deicing strategies at low temperatures.

Research on the ice-resistance performance of conical wind turbine foundation in brash ice fields

Due to the significantly higher wind energy density in high-latitude sea areas compared to other regions, the construction of offshore wind farms is shifting towards these areas. However, in high-latitude sea areas, large amounts of sea ice float on the surface during winter, making ice loads a critical factor affecting the structural safety of wind turbines. For monopile flexible wind turbines, installing an ice-breaking cone near the waterline is an effective measure to withstand the threat of sea ice. To clarify the ice resistance performance of conical wind turbine foundations in brash ice zones, this study proposes a coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM). This method is used to calculate the ice load results for a cylindrical riser, and the results were found to be in good agreement with the ice load experiment results from China University of Petroleum's wave flume (CUPWF). This validation confirms the rationality of the method. Taking a 5 MW monopile wind turbine installed with an ice-breaking cone as the research object, the time history of dynamic ice loads and the displacement response of ice-induced vibration during the interaction between the wind turbine and brash ice are simulated. Considering the water level variations caused by tides, the differences in ice resistance performance between the upright cone and the inverted cone of the ice-breaking cone are analyzed. Finally, the impact of changes in cone angle on the ice resistance performance of the wind turbine foundation is determined. The results indicate that under the impact of brash ice, the upright cone of the ice-breaking cone has a higher ice resistance capacity compared to the inverted cone. With changes in cone angle, the trends of ice loads in the horizontal and vertical directions vary oppositely. However, the overall ice resistance capacity of the wind turbine foundation decreases as the cone angle increases. This study can provide a reference for the rational design of conical wind turbines in cold regions.

Constructing carbon nanotube (CNTs)/silica superhydrophobic coating with multi-stage rough structure for long-term anti-corrosion and low-temperature anti-icing in the marine environment

The rough superhydrophobic surface is beneficial for capturing more gases underwater, which enhances corrosion and ice resistance for marine equipment. In this work, a PVAc-PVDF-FMCS (PPFMCS) multi-stage rough superhydrophobic coating was manufactured by a cold spraying method, significantly improving the anti-corrosion and anti-icing of aluminium alloy. The point-line structure was designed by cross-linking between multi-walled carbon nanotubes (MWCNTs) and silicon dioxide (SiO2), which facilitated the formation of multi-stage rough surface. The porous skeleton and interfacial adhesion of the PPFMCS coating were attributed to the introduction of polyvinylidenefluoride (PVDF) and polyvinylacetate (PVAc), respectively. The PPFMCS coating had good superhydrophobicity with a water contact angle of 163.5°, while exhibiting the outstanding performance of long-term anti-corrosion and anti-icing. The |Z|0.01 Hz value of the PPFMCS coating was still 9.62 × 109 Ω cm2 in 3.5 wt% NaCl solution for 35 days, only two orders of magnitude lower than that of the original coating, the equivalent circuits were further investigated and the metal protection is evaluated on the shore or in the deep ocean of the South China Sea. The PPFMCS coating was able to obviously delay icing for 5 min at −20 °C, the ice adhesion of its surface was as low as 85.5 kPa. The icing phase transition was analysed by a thermodynamic method. The coating also had good stability and drag reduction performance. This high-performance coating based on point-line structural design is expected to have practical applications in marine transportation, oil exploration and polar exploration.

Ice-resistant Fe3O4@PPy coating: Enhancing stability and durability with photothermal super hydrophobicity

Developing a superhydrophobic a superhydrophobic anti-icing coating with robust mechanical attributes and chemical resilience is essential for effective anti-icing protection. This study employed fluorine-modified epoxy resin as the resin matrix and Fe3O4@PPy as the photothermal filler to fabricate an ice-resistant superhydrophobic coating, renowned for its exceptional mechanical endurance and corrosion resistance. With its unique micro-nano structure, the resulting coating exhibited an impressive contact angle (CA) of 158.7° and a minimal sliding angle (SA) of <1°. Even after enduring 260 cycles of sandpaper abrasion and tape peeling tests, the coating retained a CA of 157.8° and 154.2° respectively, demonstrating remarkable mechanical durability. The Fe3O4@PPy coatings exhibit excellent ice resistance with water droplets frozen time prolonging to 524 s at −20 °C. Moreover, when exposed to a light intensity of 100 mW/cm2, the coating rapidly heated to 82.4 °C, effectively facilitating de-icing and defrosting, while reducing ice adhesion strength by 88.4 %, underscoring its exceptional anti-icing efficacy. These findings underscore the potential of durable and chemically stable anti-·icing coatings to deliver sustained anti-icing benefits and hold promising practical applications.

Unconventional Dually-Mobile Superrepellent Surfaces.

The ability of water droplets to move freely on superrepellent surfaces is a crucial feature that enables effective liquid repellency. Common superrepellent surfaces allow free motion of droplets in the Cassie state, with the liquid resting on the surface textures. However, liquid impalement into the textures generally leads to a wetting transition to the Wenzel state and droplet immobilization on the surface, thereby destroying the liquid repellency. This study reports the creation of a novel type of superrepellent surface through rational structural control combined with liquid-like surface chemistry, which allows for the free movement of water droplets and effective repellency in both the Cassie and Wenzel states. Theoretical guidelines for designing such surfaces are provided, and experimental results are consistent with theoretical analysis. Furthermore, this work demonstrates the enhanced ice resistance of the dually-mobile superrepellent surfaces, along with their distinctive self-cleaning capability to eliminate internal contaminants. This study expands the understanding of superrepellency and offers new possibilities for the development of repellent surfaces with exceptional anti-wetting properties.

Effect of phase change materials on thermophysical properties of asphalt mixtures and snow melting performance

The increased Thermal Conductivity and Thermal Diffusion Coefficient of asphalt mixtures means that the material is able to conduct and disperse heat more efficiently. In winter, this property can be used to accelerate the melting process of snow and ice, reducing the risk of road sliding due to snow and ice build-up. In this study, the thermal conductivity, thermal diffusion coefficient, and specific heat capacity of phase change asphalt (PCA) mixtures were investigated using a transient flat-plate heat source method. Analysis was performed with a thermal constant analyzer, a custom-designed thermal conductivity experiment, and a differential scanning calorimeter. Additionally, a phase change asphalt mixture thermoregulation rutting plate was prepared to evaluate its thermoregulation and snow and ice resistance under actual winter and indoor conditions. Results indicated that the thermal conductivity and thermal diffusion coefficient of PCA mixtures were superior to those of conventional asphalt mixtures. Notably, the specific heat capacity of these mixtures increased significantly within the phase change temperature range. The integration of phase change materials enhanced heat transfer within the asphalt mixtures, allowing for a delayed cooling process when temperatures decreased, with the maximum cooling range observed to be 2.8°C. Snow melting tests confirmed the early snowfall efficacy of the phase change asphalt mixture rutting plate, effectively achieving minimal snow accumulation and demonstrating the capability of 'melting light snow.'

Preparation of Silicone Coating and Its Anti-Ice and Anti-Corrosion Properties

To enhance protection against corrosion and ice on iron metal material in frigid zones, an organic silicone resin coating was prepared using four monomers. Its structure and performance was analyzed via infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), and thermal analysis (TG). Corrosion resistance of coating was tested by saltwater resistance and salt spray resistance and assessed using an electrochemical workstation, alongside anti-icing tests. The results showed that the organic silicone resin was successfully synthesized. The coatings could delay freezing onset by one-third compared to controls in low temperatures, with a detachment time also reduced by one-third, indicating excellent corrosion and ice resistance. The methylphenyl silicone resin had good anti-corrosion and anti-ice properties, with a low corrosion current density (icorr) of 0.8793 μA/cm2 and a high charge transfer resistance (Rct) of 24,930 Ω·cm2 in saline.

Numerical study of ship hydrodynamics on ice resistance during ice sheet breaking

For icebreakers to navigate polar routes, the ability to break through ice sheet is extremely important. To quantify this, technology that can estimate the mechanical behaviors of ice and ships is essential. The purpose of this study is to analyze the response of the icebreaker Araon breaking through ice sheet. Drucker-Prager yield function and fracture energy based on continuum damage mechanics were applied to the single prism ice compression simulation. The damage in the single ice initiated and evolved as the yield function and fracture energy were assigned. The icebreaking pattern was analyzed from the cone-ice sheet interaction simulations. Patterns similar to those of previous studies were observed qualitatively. The free decay of Araon was numerically analyzed using the Hydrodynamic plug-in HydroQus that was recently developed by present authors, and very accurate ship motion responses were confirmed. The effect of hydrodynamic forces on ice resistance was analyzed through ice sheet breaking simulations. It was found that radiation forces significantly affect the heave and pitch motions of the icebreaker and increase ice resistance. HydroQus has proven to be able to efficiently and accurately simulate the ship-ice interactions compared to other approaches such as computational fluid dynamics.

Study on ice resistance of Antarctic krill ship with trawl under floating ice sea conditions

IntroductionThis study focused on a Chinese Antarctic krill vessel utilising continuous pumping fishing technology. The resistance characteristics of Antarctic krill ships trawling in floating ice areas is of great significance for the navigation and fishing of krill ships in ice areas.MethodsFirstly, MATLAB programming using discrete elements combined with genetic algorithms was used to construct a normal distribution ice flow model. Secondly, a fluid-structure coupling interface is created through the contact between the fluid and the trawl grid, and the displacement and resistance of the trawl grid are evaluated on the shared interface. Finally, the effects of ice density and ship sailing speed on ice resistance were studied.Results and discussionThe results of the calculations results show that ice resistance is positively related to the concentration and speed of floating ice, moreover, there is a special speed point where ice resistance increases rapidly. As the speed increases, the proportion of trawl resistance to the total resistance continues to increase, while the proportion of ice resistance continues to decrease. This paper provides a reference for the navigation and fishing resistance assessment of Antarctic krill ships in floating ice areas.

Numerical investigations of the restriction effects on a ship navigating in pack-ice channel

This paper adopts Computational Fluid Dynamics (CFD) method and Discrete Element Method (DEM) to simulate a ship navigating in pack-ice channel considering the effects of channel restriction. First, from the simulations of the ship sailing in open-water channel by CFD, it is found that the effects of channel width on water resistance is more pronounced than the impacts by level-ice thickness. Then, based on the stable and converged flow field obtained by CFD simulations, the CFD-DEM coupling method is applied to reveal the effects of channel width and level ice thickness on ship-ice-water interactions and ice resistances at different ship speeds. The results indicate that as the channel width decreases, the accumulation of pack ice in the areas of bow and midship intensifies. The ice resistances on the bow and midship increase notably, and the lateral ice forces exhibit pronounced asymmetric and random characteristics. In extremely narrow pack-ice channels, lower ship speed results in lager ice resistance and lateral ice force on the ship. In addition, as the level ice thickness decreases, the pack ice is more easily squeezed below the level ice, resulting in the decreases of ice resistance and lateral ice force.

Design and properties of self-healing superhydrophobic CNT@SiO2 coating for anti-icing application

Superhydrophobic coatings have aroused great research interest due to their potential applications in aviation, energy, etc. However, the coatings are inclined to lose hydrophobicity when exposed to chemical corrosion, which makes them difficult to play a crucial role in some demanding areas such as road engineering. Self-healing of coatings without external stimulations is challenging but essential for reliable superhydrophobic and anti-ice properties, such an interesting topic has been rarely reported. Here we design a self-healing superhydrophobic CNT@SiO2 coating for anti-ice application. The dodecyl trimethoxysilane modified CNT@SiO2 nanoparticles are mixed with epoxy resin and sprayed to form the robust coating, which exhibits excellent superhydrophobicity (155.1°), self-healing properties and ice resistance. After seven strong alkali corrosion cycles, the self-healing rate recover more than 96% after 48 h. The coating almost doubles the freezing time even at −20 °C. The novel and simple strategy for preparing self-healing and anti-icing multifunctional coating provides a new viewpoint in surface protection.

A Framework for Structural Analysis of Icebreakers during Ramming of First-Year Ice Ridges

This paper presents a framework for structural analysis of icebreakers during ramming of first-year ice ridges. The framework links the ice-ridge load and the structural analysis based on the physical characteristics of ship–ice-ridge interactions. A ship–ice-ridge interaction study was conducted to demonstrate the feasibility of the proposed framework. A PC-2 icebreaker was chosen for the ship–ice interaction study, and the geometrical and physical properties of the ice ridge were determined based on empirical data. The ice ridge was modeled by solid elements equipped with the continuous surface cap model (CSCM). To validate the approach, the simulated ice resistance was computed using the Lindqvist solution and in situ tests of R/V Xuelong 2. First, the local ice-induced pressure on the hull shell was determined based on numerical simulations. Subsequently, the local ice pressure was applied to local deformable sub-structural models of the PC-2 icebreaker hull by means of triangular impulse loads. Finally, the structural response of sub-structural models with refined meshes was computed. This case study demonstrates that the proposed framework is suitable for structural analysis of ice-induced stresses in local hull components. The results show that the ice load and the structural response obtained based on the four first-year ice-ridge models show obvious differences. Furthermore, the ice load and corresponding structural response increases with the width of the ridge and with increasing ship speed.

Interaction between ice cover and floating platform simulated by dilated-polyhedron-based DEM

This study presents a dilated-polyhedron-based discrete element method (DPDEM) aimed at investigating the interaction between the self-propelled ice-resistant platform (IRSPP) and drifting sea ice. The IRSPP is treated as a rigid body anchored by a mooring system, providing six degrees of freedom (6-DOF) in translations and rotations. The simulation of the ice-IRSPP interaction utilizes the DPDEM, incorporating contact forces and bond-failure criteria to account for sea ice collisions and fractures, respectively. To address disparities between DEM sea ice and actual sea ice, as well as the random nature of fracture and fragmentation following IRSPP interaction, an analysis of the dimensional independence of DEM calculation elements is conducted. Additionally, the validity of DEM parameters is assessed by comparing the numerical ice resistance of various previous icebreakers with the Lindqvist formula. Then, the time history of structural ice forces, ice heeling moments, and platform motion responses under varying ice floe thicknesses are investigated. Furthermore, the influences of sea ice conditions on ice load and the value of the ice heeling moment for the IRSPP are analyzed.

A study on ice resistance prediction based on deep learning data generation method

Accurate prediction of ice resistance plays an important role in ensuring the safety of ship navigation when sailing in ice regions. This paper focuses on the design of a data generation deep learning model and an interpretable ice resistance prediction deep learning model. By selecting the appropriate ship, ice parameters and model experimental data to build the dataset, the influence of different data preprocessing methods on the model results are discussed. The processed data is expanded by Deep Convolutional Generative Adversarial Network (DCGAN). On this basis, a Graph Neural Network (GNN) is built to explain the distribution of network weights and the generalization effect of the model. The established model (GNN-DCGAN) and several ice resistance prediction methods are compared and analyzed. In addition, the design of polar ships needs to comprehensively consider the dynamic changes of ship design parameters and the mechanical properties of ice. In this paper, taking MT UIKKU as an example, the parameter sensitivity analysis is carried out to study the scope of application of the model and the contribution of different parameters. The results show that the DCGAN method can improve the prediction accuracy and application scope of GNN model. The predictions exhibit a high level of agreement with the experimental data, which can provide valuable references for the design of ship in ice regions.

A Study on the Ice Resistance Characteristics of Ships in Rafted Ice Based on the Circumferential Crack Method

In previous studies of ship–ice interactions, most studies focused on ship–level ice interactions, overlooking potential rafted ice conditions in extreme ice conditions. The purpose of this study is to develop a numerical model for predicting ship resistance in rafted ice regions. Numerical modeling of rafted ice was carried out using preset grid cells. By comparing the model test results, the accuracy and reliability of the numerical model are verified. On this basis, we undertook the analysis of the impacts of different ice thicknesses, ship speeds, bending strengths, and crushing strengths on the ice resistance of ships under level and rafted ice conditions. The results show that the ice resistance of ships is significantly higher than that of rafted ice under the condition of level ice; however, level ice and rafted ice have different effects on ship ice resistance. Compared with level ice, the ice resistance of ships navigating in rafted ice is more concentrated. The findings of the present research can serve as a technical reference for studies focused on predicting ship resistance in rafted ice regions.

Investigating Load Calculation for Broken Ice and Cylindrical Structures Using the Discrete Element Method

Ice loads are critical forces that impact the structural integrity of offshore equipment in high-latitude sea areas and play a pivotal role in the design of structures in ice-prone regions. The primary objective of this study is to investigate both experimental and numerical approaches to analyze ice loads on marine structures, elucidate their characteristics and patterns, and offer technical support for the design of structures in ice-prone areas. To achieve this goal, an ice model was built using polypropylene material, and experiments were conducted in a wave flume at room temperature to measure the ice resistance on cylindrical structures. Structural loads were assessed at various ice velocities while maintaining a fixed ice concentration. Furthermore, a high-performance discrete element technology was employed to develop a numerical simulation method for calculating ice resistance on cylindrical structures. Sensitivity analysis was conducted to evaluate the influence of discrete element density on the resistance outcomes. The predicted structural resistance for ice velocities corresponding to the experimental conditions was compared with the results obtained from the model experiment. The research findings indicate that the primary cause of ice resistance is the interaction between the structure and fragmented ice, which leads to collisions, friction, rotation, and local ice accumulation. To quantify the resistance, ice resistance coefficients were defined using an average resistance formula, representing different statistical values. These coefficients were found to remain relatively constant at varying sailing speeds. The results obtained through the discrete element method for ice resistance demonstrated a remarkable agreement with the experimental findings, both in terms of observed phenomena and numerical values. This agreement serves as evidence substantiating the effectiveness of the numerical approach. These methods offer efficient and accurate load prediction solutions for the design of structures in cold regions.

Anti-icing properties and application of superhydrophobic coatings on asphalt pavement

In regions impacted by snow and ice, icy road surfaces can significantly reduce road capacity and endanger vehicle occupants. While traditional de-icing methods, such as spreading de-icing salt and mechanical de-icing, have drawbacks such as environmental pollution and damage to road facilities, superhydrophobic coating is gaining attention as a new, environmentally friendly, and efficient anti-icing method. Superhydrophobic coating can reduce the adhesion between the ice layer and the road surface, so as to achieve the purpose of road anti-icing in a low environmental impact way. To improve the anti-icing performance of asphalt pavement under low-temperature and humid conditions and reduce the impact of snow and ice freezing disaster, we prepared nano-SiO2 superhydrophobic coatings(SSC) and nano-SiO2/graphene composite superhydrophobic coatings(SGSC) using aqueous epoxy resins, hydrophobic nano-SiO2, and sparsely layered graphene as raw materials. The coatings' wettability, ice resistance, and road performance were analyzed. The study found that the contact angles of the SSC and SGSC were 151.2° and 153.0°, respectively. The BPN value of the SGSC decreased by 12.6% after application to the asphalt pavement, but it still meets safety requirements. The coating also maintains a certain degree of ice-resistant performance within five freeze-thaw cycles. The study results indicate that superhydrophobic coatings have the potential to improve pavement ice resistance.