Ice Friction Research Articles

Ion-specific ice provides a facile approach for reducing ice friction

HypothesisIce friction plays a crucial role in both basic study and practical use. Various strategies for controlling ice friction have been developed. However, one unsolved puzzle regarding ice friction is the effect of ion–ice interplay on its tribological properties. Experiments and SimulationsHere, we conducted ice friction experiments and summarized the specific effects of hydrated ions on ice friction. By selecting cations and anions, the coefficient of ice friction can be reduced by more than 70 percent. Experimental spectra, low-field nuclear magnetic resonance (LF-NMR), density functional theory (DFT) calculations, and Molecular dynamics (MD) simulations demonstrated that the addition of ions could break the H-bonds in water. FindingsThe link between the charge density of ions and the coefficients of ice friction was revealed. A part of the ice structure was changed from an ice-like to a liquid-like interfacial water structure with the addition of ions. Lower charge density ions led to weaker ionic forces with the water molecules in the immobilized water layer, resulting in free water molecules increasing in the lubricating layer. This study provides guidance for preparing ice-making solutions with low friction coefficients and a fuller understanding of the interfacial water structure at low temperatures.

Confinement enhanced viscosity vs shear thinning in lubricated ice friction

The ice surface is known for presenting a very small kinetic friction coefficient, but the origin of this property remains highly controversial to date. In this work, we revisit recent computer simulations of ice sliding on atomically smooth substrates, using newly calculated bulk viscosities for the TIP4P/ice water model. The results show that spontaneously formed premelting films in static conditions exhibit an effective viscosity that is about twice the bulk viscosity. However, upon approaching sliding speeds in the order of m/s, the shear rate becomes very large, and the viscosities decrease by several orders of magnitude. This shows that premelting films can act as an efficient lubrication layer despite their small thickness and illustrates an interesting interplay between confinement enhanced viscosities and shear thinning. Our results suggest that the strongly thinned viscosities that operate under the high speed skating regime could largely reduce the amount of frictional heating.

High thermal conductivity and ultralow friction of two-dimensional ice by molecular dynamics simulations

Two-dimensional ice (2D ice) is a relatively new family member of ice polymorphs. While the phase transitions and growth kinetics of 2D ice have aroused intensive investigation, its thermal and mechanical properties are seldom studied. The unique 2D structure of this polymorph suggests that it may possess distinct physical characteristics compared to its bulk counterparts. In this work, the thermal conductivities and friction of 2D ice were systematically studied by molecular dynamics (MD) simulations. It was found that the thermal conductivities of 2D ice show a strong dependence on their length and the extrapolated value of the infinite system can achieve ∼4.7 W/(m∙K), which is notably higher than that of bulk phase of ice Ih ∼1.5 W/(m∙K). Decreasing temperature or applying mechanical strains can both increase the thermal conductivity of 2D ice, which can be explained by structure or phonon analyses. 2D ice also exhibits an ultralow friction of ∼0.24 nN when sliding upon a graphene substrate, lower than that of ice Ih ∼0.70 nN at the same sliding conditions. With the decrease in temperature or the increase in normal load, the friction coefficient of 2D ice exhibits a downward trend, and it could be as low as ∼0.005, indicating superlubricity. The analysis on structural lubricity suggests that ordered but mismatched crystal-crystal contacts have lower friction than disordered case. The results on high thermal conductivity and ultralow friction would guide the potential application of 2D ice in efficient thermal management or design of nanofluidic devices.

Deformation lines in Arctic sea ice: intersection angle distribution and mechanical properties

Abstract. Despite its relevance for the Arctic climate and ecosystem, modeling sea-ice deformation, i.e., the opening, shearing, and ridging of sea ice, along linear kinematic features (LKFs) remains challenging, as the mechanical properties of sea ice are not yet fully understood. The intersection angles between LKFs provide valuable information on the internal mechanical properties, as they are linked to them. Currently, the LKFs emerging from sea-ice rheological models do not reproduce the observed LKF intersection angles, pointing to a gap in the model physics. We aim to obtain an intersection angle distribution (IAD) from observational data to serve as a reference for high-resolution sea-ice models and to infer the mechanical properties of the sea-ice cover. We use the sea-ice vorticity to discriminate between acute and obtuse LKF intersection angles within two sea-ice deformation datasets: the RADARSAT Geophysical Processor System (RGPS) and a new dataset from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) drift experiment. Acute angles dominate the IAD, with single peaks at 48∘±2 and 45∘±7. The IAD agrees well between both datasets, despite the difference in scale, time period, and geographical location. The divergence and shear rates of the LKFs also have the same distribution. The dilatancy angle (the ratio of shear and divergence) is not correlated with the intersection angle. Using the IAD, we infer two important mechanical properties of the sea ice: we found an internal angle of friction in sea ice of μI=0.66±0.02 and μI=0.75±0.05. The shape of the yield curve or the plastic potential derived from the observed IAD resembles a teardrop or a Mohr–Coulomb shape. With these new insights, sea-ice rheologies used in models can be adapted or redesigned to improve the representation of sea-ice deformation.

Study on the ice friction characteristics

Ice friction plays a vital role in different fields, including glaciology, polar runways, and winter sports, the mechanisms of which are complex and affected by many parameters, such as temperature, velocity, and load. It is commonly accepted that the frictional characteristics of ice can be attributed to a lubricating layer. Sphere-on-ice friction experiments were conducted to study the influence of temperature, pressure, and velocity on ice friction. The lubrication state of ice friction under different conditions was analyzed, and it was found that the contact angle and roughness were crucial factors. Characterizations of the worn surfaces done using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and three-dimensional white-light interference indicated that abrasive and oxidation wear were the main wear mechanisms arising from ice friction. The underlying mechanism was explored using molecular dynamics (MD) simulations. The results suggested that the effects of velocity, temperature, and load on the presence of hydrogen bonding alter the fluidity of the lubricating layer existing between the ice and sphere, which in turn affects the ice friction characteristics. In the lubricating layer, the concentrations of water molecules near the sliders and ice were higher than those in the inner water. Moreover, the adsorption energy verified that water molecules tended to be adsorbed on the ice and sliders. In addition, the calculation results indicated that some water molecules were re-oriented in the ice friction because spikes were observed in the radial distribution function (RDF) graphs.

Evolution of Global Ocean Tide Levels Since the Last Glacial Maximum

AbstractThis study addresses the evolution of global tidal dynamics since the Last Glacial Maximum focusing on the extraction of tidal levels that are vital for the interpretation of geologic sea‐level markers. For this purpose, we employ a truly‐global barotropic ocean tide model which considers the non‐local effect of Self‐Attraction and Loading. A comparison to a global tide gauge data set for modern conditions yields agreement levels of 65%–70%. As the chosen model is data‐unconstrained, and the considered dissipation mechanisms are well understood, it does not have to be re‐tuned for altered paleoceanographic conditions. In agreement with prior studies, we find that changes in bathymetry during glaciation and deglaciation do exert critical control over the modeling results with minor impact by ocean stratification and sea ice friction. Simulations of 4 major partial tides are repeated in time steps of 0.5–1 ka and augmented by 4 additional partial tides estimated via linear admittance. These are then used to derive time series from which the tidal levels are determined and provided as a global data set conforming to the HOLSEA format. The modeling results indicate a strengthened tidal resonance by M2, but also by O1, under glacial conditions, in accordance with prior studies. Especially, a number of prominent changes in local resonance conditions are identified, that impact the tidal levels up to several meters difference. Among other regions, resonant features are predicted for the North Atlantic, the South China Sea, and the Arctic Ocean.

A numerical investigation on the energetics of a current along an ice-covered continental slope

Abstract. The Chukchi Slope Current is a westward-flowing current along the Chukchi slope, which carries Pacific-origin water from the Chukchi shelf into the Canada Basin and helps set the regional hydrographic structure and ecosystem. Using a set of experiments with an idealized primitive equation numerical model, we investigate the energetics of the slope current during the ice-covered period. Numerical calculations show that the growth of surface eddies is suppressed by the ice friction, while perturbations at mid-depths can grow into eddies, consistent with linear instability analysis. However, because the ice stress is spatially variable, it is able to drive Ekman pumping to decrease the available potential energy (APE) and kinetic energy of both the mean flow and mesoscale eddies over a vertical scale of 100 m, well outside the frictional Ekman layer. The rate at which the APE changes is determined by the vertical density flux, which is negative as the ice-induced Ekman pumping advects lighter (denser) water upward (downward). A scaling analysis shows that Ekman pumping will dominate the release of APE for large-scale flows, but the effect of baroclinic instability is also important when the horizontal scale of the mean flow is the baroclinic deformation radius and the eddy velocity is comparable to the mean flow velocity. Our numerical results highlight the importance of ice friction in the energetics of the slope current and eddies, and this may be relevant to other ice-covered regions.

Ultrahigh Lubricity between Two-Dimensional Ice and Two-Dimensional Atomic Layers.

Low temperature and high humidity conditions significantly degrade the performance of solid-state lubricants consisting of van der Waals (vdW) atomic layers, owing to the liquid water layer attached/intercalated to the vdW layers, which greatly enhances the interlayer friction. However, using low temperature in situ atomic force microscopy (AFM) and friction force microscopy (FFM), we unveil the unexpected ultralow friction between two-dimensional (2D) ice, a solid phase of water confined to the 2D space, and the 2D molybdenum disulfides (MoS2). The friction of MoS2 and 2D ice is reduced by more than 30% as compared to bare MoS2 and the rigid surface. The phase transition of liquid water into 2D ice under mechanical compression has also been observed. These new findings can be applied as novel frictionless water/ice transport technology in nanofluidic systems and promising high performance lubricants for operating in low temperature and high humidity environments.

A trajectory simulation model to analyse the factors influencing the descent of a Skeleton athlete

Subtle differences in aerodynamic drag, ice friction and sprint start, all influenced by the skill and physique of athletes, determine the descent time and hence competitive success in the sport of Skeleton. A trajectory based simulation was created by parameterising the geometry of the Altenberg Ice Track in Saxony, Germany to find the physically realistic descent time that captures the physics of the aerodynamic drag, ice friction and sprint start. A sensitivity study was used to analyse the influence of each factor on the overall performance down a fixed mid-line trajectory. Comparisons are made to the actual descent times to confirm applicability for a set of male and female sliders. It was found that the combined mass of the athlete and sled should be maximised within the rules, the initial velocity from the push should be as fast as possible, the aerodynamic drag should be optimised for each athlete and the ice friction of the runners reduced to their lowest limit. If each variable is optimum, then the final race standings will depend solely on the skill of the athlete traversing the ice track by finding the ‘best’ trajectory.

A new mechanism of the interfacial water film dominating low ice friction.

It is generally accepted that ice is slippery due to an interfacial water film wetting the ice surface. Despite the current progress in research, the mechanism of low ice friction is not clear, and especially little is known about the behavior of this surface water film under shear and how the sheared interfacial water film influences ice friction. In our work, we investigated the ordering and diffusion coefficient of the interfacial water film and the friction of ice sliding on an atomically smooth solid substrate at the atomic level using molecular dynamics simulations. There are two layers of water molecules at the ice-solid interface that exhibit properties very different from bulk ice. The ice-adjacent water layer is ice-like, and the solid-adjacent water layer is liquid-like. This liquid-like layer behaves in the manner of "confined water," with high viscosity while maintaining fluidity, leading to the slipperiness of the ice. Furthermore, we found that the interfacial water exhibits shear thinning behavior, which connects the structure of the interfacial water film to the coefficient of friction of the ice surface. We propose a new ice friction mechanism based on shear thinning that is applicable to this interfacial water film structure.

Ice friction at the nanoscale

The origin of ice slipperiness has been a matter of great controversy for more than a century, but an atomistic understanding of ice friction is still lacking. Here, we perform computer simulations of an atomically smooth substrate sliding on ice. In a large temperature range between 230 and 266 K, hydrophobic sliders exhibit a premelting layer similar to that found at the ice/air interface. On the contrary, hydrophilic sliders show larger premelting and a strong increase of the first adsorption layer. The nonequilibrium simulations show that premelting films of barely one-nanometer thickness are sufficient to provide a lubricating quasi-liquid layer with rheological properties similar to bulk undercooled water. Upon shearing, the films display a pattern consistent with lubricating Couette flow, but the boundary conditions at the wall vary strongly with the substrate's interactions. Hydrophobic walls exhibit large slip, while hydrophilic walls obey stick boundary conditions with small negative slip. By compressing ice above atmospheric pressure, the lubricating layer grows continuously, and the rheological properties approach bulk-like behavior. Below 260 K, the equilibrium premelting films decrease significantly. However, a very large slip persists on the hydrophobic walls, while the increased friction on hydrophilic walls is sufficient to melt ice and create a lubrication layer in a few nanoseconds. Our results show that the atomic-scale frictional behavior of ice is a combination of spontaneous premelting, pressure melting, and frictional heating.

Experimental Measurement of Ice-Curling Stone Friction Coefficient Based on Computer Vision Technology: A Case Study of “Ice Cube” for 2022 Beijing Winter Olympics

In the curling sport, the coefficient of friction between the curling stone and pebbled ice is crucial to predict the motion trajectory. However, the theoretical and experimental investigations on stone–ice friction are limited, mainly due to the limitations of the field measurement techniques and the inadequacy of the experimental data from professional curling rinks. In this paper, on-site measurement of the stone–ice friction coefficient in a prefabricated ice rink for the Beijing Winter Olympics curling event was carried out based on computer vision technology. Firstly, a procedure to determine the location of the curling stone was proposed using YOLO-V3 (You Only Look Once, Version 3) deep neural networks and the CSRT Object tracking algorithm. Video data was recorded during the curling stone throwing experiments, and the friction coefficient was extracted. Furthermore, the influence of the sliding velocity on the friction coefficient was discussed. Comparison with published experimental data and models and verification of the obtained results, using a sensor-based method, were conducted. Results show that the coefficient of friction (ranging from 0.006 to 0.016) decreased with increasing sliding velocity, due to the presence of a liquid-like layer. Our obtained results were consistent with the literature data and the friction model of Lozowski. In addition, the experimental results of the computer vision technique method and the accelerometer sensor method showed remarkable agreement, supporting the accuracy and reliability of our proposed measurement procedure based on deep learning.

An Empirical Study on the Effects of Sea Ice on Ship Tonnage per Centimeter and Cargo Operations

Abstract Many ports around the world are threatened by sea ice. Access by merchant ships to these ports is ensured by ice-breaking services. For the sensitivity of calculations of the amount of cargo on vessels carrying out loading and discharging in waters covered with ice, the calculations need to be modified. This study aims to investigate the effects of sea ice in different thicknesses on the calculations of the cargo amounts, especially the effects on the tonnage per centimeter (TPC) values of the vessels. There is a limited number of studies on ice resistance of zero-speed vessels. An experimental study was performed to gauge the impact of ice on vessel draughts on a scale ship model. The scaled TPC weights were applied under two separate loading conditions on the scale model ship. Such processes were repeated for various ice thicknesses. The results indicated that an increase in TPC values was in a linear relationship with ice thickness and was found under both loading conditions. In analyses based on the scale model according to the draft marks, the ice friction created an overloaded case. In the stability booklets, it is assumed that adding the amount of increase in TPC value as a correction would resolve disputes over the amount of loaded cargo and can circumvent overloading cases.

Changes in surface velocities over four decades on the Laurichard rock glacier (French Alps)

AbstractThe longest time series of surface velocities recorded on a rock glacier in the French Alps, covering more than three decades, has been recorded since 1983 on the Laurichard rock glacier (Ecrins range). The time signal of velocity changes is extracted from variance analyses separating time and space variabilities on the rock glacier surface to provide an average‐wide time signal. We show that changes in velocity from year to year are virtually uniform at all locations with homogeneous accelerations or decelerations on the scale of the rock glacier as a whole. The spatial structure of velocity was found to be nearly at steady state over 35 years. Nonlinear effects are located in low‐velocity areas such as the rock glacier margins where accelerations/decelerations tend to be proportional to the local velocity. Over the period of record, a long‐term trend in rock glacier acceleration was detected with a rate of +0.2 m/yr per decade. Two main phases of acceleration were identified from the mid‐1980s to 1999 and from 2010 to 2015. In between, those two periods were interrupted by a 10‐year period of almost steady‐state velocities with an abrupt deceleration from 2006 to 2009 of −0.35 m/yr. The process of internal increases in ice temperatures alone (and associated changes in creep rates) would seem insufficient to explain the long‐term rise of surface velocities and their annual variations. Changes in the liquid water are a possible contributing factor, due to the injection of seasonal water caused by melting snow cover or internal melt due to heat generated by enhanced ice creep and friction in the ice/debris mixture.

Numerical model for a failure process of an ice sheet

Model for describing a three-dimensional continuous failure process of an ice sheet is introduced. The presented model is based on the combined finite-discrete element method. The ice sheet consists of polyhedral rigid discrete elements joined by a lattice of Timoshenko beam elements, which go through cohesive softening upon sheet failure. The contact model accounts for inter-particle friction and local failure of ice in contacts. The model is carefully validated against a laboratory experiment, where an ice sheet is pushed against an inclined plane. Convincing agreement between the modelled and experimental failure process is found. The effect of ice sheet tessellation and element size is tested and found to be only moderate. The model compares favorably to earlier ones: The modelling and the experimental results agree, the domain sizes used can be large, and the modelled failure processes are long in duration. Requirements for numerical modelling of ice failure processes are discussed.

Fracture, Friction, and Permeability of Ice

Water ice Ih exhibits brittle behavior when rapidly loaded. Under tension, it fails via crack nucleation and propagation. Compressive failure is more complicated. Under low confinement, cracks slide and interact to form a frictional (Coulombic) fault. Under high confinement, frictional sliding is suppressed and adiabatic heating through crystallographic slip leads to the formation of a plastic fault. The coefficient of static friction increases with time under load, owing to creep of asperities in contact. The coefficient of kinetic (dynamic) friction, set by the ratio of asperity shear strength to hardness, increases with velocity at lower speeds and decreases at higher speeds as contacts melt through frictional heating. Microcracks, upon reaching a critical number density (which near the ductile-to-brittle transition is nearly constant above a certain strain rate), form a pathway for percolation. Additional work is needed on the effects of porosity and crack healing. ▪ An understanding of brittle failure is essential to better predict the integrity of the Arctic and Antarctic sea ice covers and the tectonic evolution of the icy crusts of Enceladus, Europa, and other extraterrestrial satellites. ▪ Fundamental to the brittle failure of ice is the initiation and propagation of microcracks, frictional sliding across crack faces, and localization of strain through both crack interaction and adiabatic heating.

Resistance Performance of a Ship in Model-Scaled Brash Ice Fields Using CFD and DEM Coupling Model

The brash ice channel formed with icebreaker navigation is a normal working scenario for ice-going vessels. Therefore, it is necessary to study brash ice resistance in this condition. In this study, CFD and DEM coupling methods were adopted to investigate the resistance performance of a ship sailing in model-scaled brash ice fields, considering the collision force and friction resistance, among the brash ice, and the water resistance and hydrodynamic force of brash ice, which make up physical scenarios of navigation in the brash ice channel. To study the effect of aforementioned parameters on the average total resistance, the time step, iteration, and brash ice stiffness were analyzed; we found that a time step of 0.02 s, iteration of 10, and brash ice stiffness of 1000 N/m that showed better repeatability of the physical phenomenon, and it was used to reproduce working conditions created in the HSVA ice tank test. The error between the numerical simulation results and the test results is less than 5%, which shows the robustness of the present coupling strategy. Finally, the effects of ship–ice friction coefficient, ice thickness, ice shape, brash ice channel width, and ice concentration on the resistance of the ship were investigated and verified with the published results.

Wear characteristics and degradation mechanism of natural pumice concrete under ice friction during ice flood season

Wear amount of ice on pumice concrete was investigated to understand wear mechanism of natural pumice concrete (NPC) during ice flood season of the Yellow River in China. Sawn NPC is used as the research object in this study. Strength grades (LC20, LC30, and LC40), ice pressure (1–5 KPa), and environment temperature (0 °C to − 20 °C) on the wear amount of natural pumice concrete as well as changes of surface topography and pore structure characteristics of NPC were analyzed with a super–depth–of–field microscope through the anti–ice wear test. Results showed that apertures increase with the increase of the wear amount because pumice aggregate and cementitious material jointly resist liquid pressure and cutting and fatigue wear modes of the NPC are caused by ice. Detached free abrasive particles cause scratches and wear on the surface and gradually form inward cracks, which cause the pore wall to break and result in the increase of apertures. A wear model with concrete strength grade, ice pressure, and environment temperature as variables combined with test data and degradation mechanism is established. The results of this study can provide a theoretical basis for the application of NPC in the Yellow River during ice flood season.

Tidal Modulation of Ice Streams: Effect of Periodic Sliding Velocity on Ice Friction and Healing

Basal slip along glaciers and ice streams can be significantly modified by external time-dependent forcing, although it is not clear why some systems are more sensitive to tidal stresses. We have conducted a series of laboratory experiments to explore the effect of time varying load point velocity on ice-on-rock friction. Varying the load point velocity induces shear stress forcing, making this an analogous simulation of aspects of ice stream tidal modulation. Ambient pressure, double-direct shear experiments were conducted in a cryogenic servo-controlled biaxial deformation apparatus at temperatures between −2°C and −16°C. In addition to a background, median velocity (1 and 10 μm/s), a sinusoidal velocity was applied to the central sliding sample over a range of periods and amplitudes. Normal stress was held constant over each run (0.1, 0.5 or 1 MPa) and the shear stress was measured. Over the range of parameters studied, the full spectrum of slip behavior from creeping to slow-slip to stick-slip was observed, similar to the diversity of sliding styles observed in Antarctic and Greenland ice streams. Under conditions in which the amplitude of oscillation is equal to the median velocity, significant healing occurs as velocity approaches zero, causing a high-amplitude change in friction. The amplitude of the event increases with increasing period (i.e. hold time). At high normal stress, velocity oscillations force an otherwise stable system to behave unstably, with consistently-timed events during every cycle. Rate-state friction parameters determined from velocity steps show that the ice-rock interface is velocity strengthening. A companion paper describes a method of analyzing the oscillatory data directly. Forward modeling of a sinusoidally-driven slider block, using rate-and-state dependent friction formulation and experimentally derived parameters, successfully predicts the experimental output in all but a few cases.

Ice-based triboelectric nanogenerator with low friction and self-healing properties for energy harvesting and ice broken warning

In this paper, a new type of ice-based triboelectric nanogenerator (ICE-TENG) has been fabricated to harvest energy in cold weather. Ice is a preferred material for designing TENGs in cold winter, alpine or snowy mountain regions because of its cleanness, environmental protection, abundant reserves, low friction, and self-healing properties. The short-circuit current and voltage can achieve 2.4 µA and 48 V with 4 mm thickness of ice layer, 30 N loadings, and 5 Hz contact frequency, which can be useful in some practical applications such as lighting LEDs and charging capacitors. The ICE-TENG possesses excellent stability and can reach an output power of 35 µW under 20 MΩ loading resistance. The coefficient of friction between ice and other friction pairs is negligible, and it can even become super-slippery with the coefficient of friction below 0.008. Thus, the wear of the friction pairs is small, which can help TENG to have a long working life. Besides, due to the rapid phase change of ice, the ICE-TENG exhibits a commendable self-healing ability and maintains the original output performance after several damage and repair processes. To simulate the practical applications, a single electrode ICE-TENG driven by walking has been designed for harvesting energy on the ice surface. Because of the difference in electric output before and after the ice fragmentation, the ICE-TENGs are designed to construct a warning system to remind the danger when the ice surface suddenly shatters. Moreover, such ICE-TENGs are capable of lighting “ICE” LEDs and powering an electric watch with footsteps. This illustrates a promising potential in self-powered systems such as danger warning, charge shortage, and energy harvesting.