Ice Friction Research Articles

The ice friction of polymeric substrates

A fixture has been designed and utilized in conjunction with a conventional rotational rheometer to measure and study the mechanisms of friction of polymeric surfaces (ultra-high molecular weight polyethylene, polytetrafluoroethylene and polymethylmethacrylate) on ice. Ice friction experiments were performed at various sliding velocities (from 0.0079 to 1.96m/s), temperatures (from −25°C to −1.5°C), and various degrees of surface roughness. It was found that the magnitude of the sliding velocity and temperature play important roles in ice friction. Friction coefficient decreases with increasing temperature at high sliding velocities (from 0.79 to 1.96m/s) due to surface lubrication. However, at lower sliding velocities (from 0.0079 to 0.079m/s) the friction coefficient initially decreases and then increases due to the modification of the real contact area on the ice surface. The ice friction coefficient was found to be nearly independent of relatively small differences in surface roughness. Finally, the ice friction coefficient of three polymer substrates exhibiting very different static contact angles, from hydrophilic to hydrophobic, was found to scale inversely with their water static contact angle.

Friction on ice: stick and slip

Faraday made investigations into behaviour of ice and snow. He was ahead of his time. Our paper briefly describes the current state of knowledge in ice friction and adhesion and its historical development. Important aspects of these phenomena in engineering, winter sports and the natural environment are considered. We report new results for static and dynamic friction of a metal (steel) and a polymer (PMMA) on ice over a range of temperatures (-3 to -13 degrees C), and interpret the behaviour by considering processes that operate at the interface and in the bulk of the materials. Clearly the chemical and thermomechanical properties of steel, PMMA and ice differ. The thermomechanical properties of ice itself also vary within the temperature range examined. We find higher static friction with increasing time, and a curious difference in the behaviour of the metal and polymer with temperature. We explain the results by considering the materials' stiffness, plastic deformation and creep, the ductile/brittle transition in ice, thermal properties, physicochemical properties of the surfaces and the real area of contact.

206 カーリングストーンの氷摩擦係数とカール比の測定(カーリング)

206 カーリングストーンの氷摩擦係数とカール比の測定(カーリング)

Experimental analysis of ice friction in the sport of bobsleigh

We report the first derivation of the coefficient of friction between bobsleigh runners and ice from experimental measurements performed in a controlled environment. In a series of experiments on both horizontal ice and a track sloped at 6.80°, a radar gun was used to sample the speed of a moving sled in the range of (1–10) m/s at a sample rate of 31.25 Hz. The acceleration of the sled, and thus the coefficient of friction, was extracted from these data, with a value of (4.2 ± 0.9) × 10−3 for the coefficient of friction associated with a set of two-man bobsleigh runners. There was no detectable variation in the coefficient of friction with velocity at this range of speeds and experimental accuracy. This result improves our knowledge of this coefficient over currently accepted values determined from indirect measurements, and indicates that the coefficient is lower than the currently accepted range.

Frictional sliding across Coulombic faults in first‐year sea ice: A comparison with freshwater ice

Frictional sliding plays a fundamental role in the deformation of the Arctic Ocean ice cover and in ice‐structure interactions. To examine its character, sliding experiments were performed along freshly created Coulombic faults in first‐year S2 sea ice harvested from the Beaufort Sea during the winters of 2003, 2007, and 2009. For comparison, and to complement experiments performed earlier, we also examined freshwater ice of similar microstructure. The principal variables were sliding velocity (from 8 × 10−7 m s−1 to 4 × 10−3 m s−1), temperature (−40°C, −10°C, and −3°C) and normal stress (from 0.02 to 2.7 MPa). Over the ranges explored, the coefficient of friction varies by a factor of four, from ∼0.4 to ∼1.6. The coefficient for both materials reaches a maximum value at an intermediate velocity, which is an order of magnitude higher for sea ice (∼10−4 m s−1) than for freshwater ice (∼10−5 m s−1). At lower velocities, sliding is characterized by velocity strengthening where, for a given velocity, the coefficient of friction of sea ice is lower than that of freshwater ice. At higher velocities, sliding is characterized by velocity weakening, where, for a given velocity, the coefficients of friction for sea ice is closer to that of freshwater ice. Velocity strengthening is explained in terms of creep deformation within contact zones along the fault. Velocity weakening is tentatively attributed to a combination of fracture and localized melting. An implication of stable versus unstable sliding is discussed for sea ice mechanics.

Tyre friction behaviour under abrupt wheel torque transients on slippery road surfaces: experimental analysis and modelling

The paper shows that, during abrupt wheel torque transients for ice surface and low vehicle speeds, the tyre can develop significantly larger longitudinal force than the peak value of the tyre static curve. This so-called dynamic tyre friction potential (DTFP) effect has many influencing factors such as the rate of change of the wheel torque, the vehicle speed, and the tyre dwell time. The paper presents a detailed analysis of the DTFP behaviour based on the experimental data collected by using an in-wheel motor-based tyre test vehicle. The analysis results and an insight into the brush structure of a tyre model lead to the hypothesis that the different influencing factors may be predominantly explained by the bristle dwell time (BDT) effect. Following this hypothesis, the LuGre model of the tyre friction dynamics is extended with a physical BDT sub-model. The experimental validation results show that the proposed model can accurately capture the low-speed tyre–ice friction behaviour during abrupt wheel torque transients.

Skating performance in ice hockey when using a flared skate blade design

Abstract In ice hockey the skating speed and the agility of the players depend on the interaction between the skate blade and the ice. A skate blade design that flares outward toward the bottom of the blade changes the geometry of the blade–ice contact. A previous study showed reduced blade–ice friction with flared blades set vertically on the ice and mechanical considerations of the blade–ice penetration suggest that flared blades might also improve the lateral grip on the ice in turns or during push-off. However, skating is a complex motion depending on multifaceted blade–ice interaction mechanisms and on the skater's individual technique. A modification of the blade design may thus not cause the desired effect in actual skating or may be uncomfortable for the players. The purpose of this study was therefore to test if a flared blade design measurably improves skating performance of ice hockey players in selected skating tests. Twelve experienced players of a university ice hockey team volunteered for a glide turn test and a straight skating test. In both tests, each subject performed five trials on the flared and on the standard skate blade. The run times were used to quantify skating performance. In straight skating, acceleration and maximum speed were assessed. After the tests, the players' subjective opinions about the two blades were evaluated using a visual analog scale. The statistical analysis used effect sizes to test for blade effects on the run times within subjects and two-way repeated measures ANOVAs to test for group effects. The subjects performed on average 1.3%, 0.9%, and 1.3% faster on the flared blades in the glide turn test, in the acceleration and the maximum speed of the straight skating test, respectively. The blade effect was statistically significant (p = 0.016, p = 0.049, p = 0.007), however, the individual results suggested that not all subjects benefited from the modified blade design. This might indicate that some adaptation of the players' skating technique to the blade condition was necessary. The results of this study show that relative simple modifications on ice hockey equipment can lead to measurable improvements in skating performance. Further research into the mechanics of the blade–ice interaction and new designs for skate blades may therefore be able to further improve selected performance variables in ice hockey.

A driver model of a two-man bobsleigh

Up to now, the optimization of structural parameters affecting the performance of a bobsleigh has been carried out mainly on the basis of athletes’ feedback, thus leading to a series of small modifications without univocal guidelines. Even though on-track tests represent a basic step for the final tuning of the sled, experimentation does not seem to represent an appropriate tool to objectively determine the influence of such structural parameters on the overall performance. In fact, their effect can easily be masked by driving errors, changes in the ice surface conditions and temperature thus requiring repeated tests for achieving statistical evidence. For this reason, numerical analysis, carried out with a 3D model of the bobsled, turns out to be a privileged instrument to optimize bob design although limitations in the sled model (e.g. ice friction properties that still have to be fully understood) may affect the obtained results. However, such tool is able to provide useful indications only if a correct driver model is implemented. This work focuses on the development of a numerical model of a bobsleigh driver that aims at reproducing the driving behaviour of real-world cup drivers and is basically made up of two steps: the identification of the trajectory that allows minimizing run time and the determination of the driver’s inputs to exactly follow that trajectory. For comparison purposes, the simulated driver’s inputs are compared with recorded ones on Cesana Pariol Olympic track.

A rate and state friction law for saline ice

Sea ice friction models are necessary to predict the nature of interactions between sea ice floes. These interactions are of interest on a range of scales, for example, to predict loads on engineering structures in icy waters or to understand the basin-scale motion of sea ice. Many models use Amonton's friction law due to its simplicity. More advanced models allow for hydrodynamic lubrication and refreezing of asperities; however, modeling these processes leads to greatly increased complexity. In this paper we propose, by analogy with rock physics, that a rate- and state-dependent friction law allows us to incorporate memory (and thus the effects of lubrication and bonding) into ice friction models without a great increase in complexity. We support this proposal with experimental data on both the laboratory (∼0.1 m) and ice tank (∼1 m) scale. These experiments show that the effects of static contact under normal load can be incorporated into a friction model. We find the parameters for a first-order rate and state model to be A = 0.310, B = 0.382, and μ0 = 0.872. Such a model then allows us to make predictions about the nature of memory effects in moving ice-ice contacts.

Nanopatterned Metallic Surfaces: Their Wettability and Impact on Ice Friction

A distinct surface microstructure was created on the surface of metal alloys and highly pure metals by using a one-step femtosecond laser process. After irradiation the surfaces show initially superhydrophilic behavior with complete wetting. With time and exposure to ambient air, however, the measured contact angles on these surfaces increase significantly. Eventually, all surfaces become hydrophobic and support Cassie-like hydrophobicity with contact angles beyond 150° and very low hysteresis. The increase in contact angle with time correlates with the amount of carbon detected on the irradiated surface, which suggests that the time dependency of the surface wettability depends on the combined effect of surface morphology and surface chemistry. The nanopatterned superhydrophobic substrates were tested in ice friction tests. At temperatures close to the melting point and relatively high speeds of the metal slider, the laser created nanoroughness and hydrophobicity significantly decrease ice friction. This decrease in friction is attributed to the suppression of capillary bridges between the slider and ice surface, which contributes considerably to the overall frictional resistance.

Does the normal stress parallel to the sliding plane affect the friction of ice upon ice?

AbstractSliding experiments were performed at −10°C on smooth surfaces of freshwater columnar-grained S2 ice sliding against itself at a velocity of 8 × 10−4 m s−1, with the purpose of examining whether normal stress parallel to the sliding plane affects frictional resistance. This component of the stress tensor was varied (0.20–1.83 MPa) using a loading system operated under biaxial compression, by orienting the sliding plane at two different angles, 26° and 64°, with respect to the principal loading direction. Under these conditions, no evidence was found to indicate that the normal stress in the direction of sliding affects the friction coefficient.

An approximate simulation model for initial luge track design

Competitive and recreational sport on artificial ice tracks has grown in popularity. For track design one needs knowledge of the expected speed and acceleration of the luge on the ice track. The purpose of this study was to develop an approximate simulation model for luge in order to support the initial design of new ice tracks. Forces considered were weight, drag, friction, and surface reaction force. The trajectory of the luge on the ice track was estimated using a quasi-static force balance and a 1d equation of motion was solved along that trajectory. The drag area and the coefficient of friction for two runs were determined by parameter identification using split times of five sections of the Whistler Olympic ice track. The values obtained agreed with experimental data from ice friction and wind tunnel measurements. To validate the ability of the model to predict speed and accelerations normal to the track surface, a luge was equipped with an accelerometer to record the normal acceleration during the entire run. Simulated and measured normal accelerations agreed well. In a parameter study the vertical drop and the individual turn radii turned out to be the main variables that determine speed and acceleration. Thus the safety of a new ice track is mainly ensured in the planning phase, in which the use of a simulation model similar to this is essential.

Experimental studies on shear failure of freeze-bonds in saline ice:

Abstract This paper is the second of two papers that present and discusses the results from experiments where artificially created freeze-bonds made from saline ice were tested on direct shear with the freeze-bond oriented horizontally. It discusses the friction forces after freeze-bond failure and the failure energy. The friction force showed increasing linear trends with a non-zero intercept when plotted against the normal force. It shows that for low confinements Amonton's law is insufficient. For larger confinements the values of friction coefficient were in the range of previously reported measurements in ice–ice friction. A slightly decreasing trend of the frictional forces was found when the initial ice temperature increased. A Mohr–Coulomb type of model was proposed to model the ice–ice frictional stresses as function of the normal stresses. An empirical model was obtained to describe freeze-bond failure and subsequent deformation by introducing softening of the cohesion and angle of internal friction. The failure energy had similar trends to those observed for the freeze-bond shear strength when plotted against normal confinement, initial ice temperature and submersion time. Quadratic fitting to the data of failure energy as a function of freeze-bond shear strength allowed the estimation of the elastic shear modulus of the freeze-bond by applying a simple rheological model. The values found were between 2 kPa and 6 kPa which are very low compared with the shear elastic modulus for the ice blocks.

Does skate sharpening affect individual skating performance in an agility course in ice hockey?

When sharpening ice hockey blades a hollow is created at the running surface of the blade. This study aimed to quantify the effect of different blade hollows on (a) blade–ice friction, (b) skating performance in an agility course, and (c) players’ perception of blade sharpness, performance, and comfort. Friction was quantified by measuring the deceleration of a sled running on the blades. Skating performance was tested with 15 volunteers performing a total of 9 trials on 3 different hollow radii. Perception was assessed using a questionnaire. Friction increased with decreasing hollow radius. Skating performance was significantly impeded at a hollow radius of 3.18 mm. Within the range of 9.53–22.23 mm performance differences were subject specific and several subjects showed no differences. Players appeared to be not sensitive enough to identify hollow radii, and only half of the subjects ranked their performance correctly.

Physics of ice friction

Although the study of friction has a long history, ice friction has only been investigated during the last century. The basic physical concepts underlying the different friction regimes, such as boundary, mixed, and hydrodynamic friction are also relevant to ice friction. However, these friction regimes must be described with respect to the thickness of the lubricating liquidlike layer on ice. In this review the state of knowledge on the physics of ice friction is discussed. Surface melting theories are introduced. These theories attempt to explain the existence and nature of the liquidlike surface layer on ice at any temperature and without any load applied. Pressure melting, as the long-time explanation for the ease of ice friction, is discussed, together with the prevailing theory of frictional heating. The various laboratory setups for ice friction measurements are presented as well as their advantages and disadvantages. The individual influence of the different parameters on the coefficient of ice friction is discussed; these include the effects of temperature, sliding velocity, normal force exerted by the sliding object, the contact area between ice and slider, relative humidity, and also properties of the slider material such as surface roughness, surface structure, wettability, and thermal conductivity. Finally, the most important ice friction models based on the frictional heating theory are briefly introduced and research directions on the subject of ice friction are discussed.

Ice friction: the effect of thermal conductivity

AbstractThe effect of thermal conductivity on ice friction is studied systematically for different metallic slider materials over a wide range of temperatures, and sliding velocities. By thermally insulating the slider with fiberglass, the isolated effect of thermal conductivity on ice friction is investigated. A decrease of the friction coefficient in the boundary friction regime and an earlier onset of the mixed friction regime in terms of sliding velocity are found. Furthermore, the dependence of the ice friction coefficient on sliding velocity is compared for different sliding materials. It is found that the influence and importance of thermal conductivity decreases with increasing sliding velocity.

Curl Mechanism of a Curling Stone on Ice Pebbles

We present a physical model that accounts for the curl mechanism of a curling stone on ice pebbles. The evaporation-abrasion model is based on the two essential features of curling: pebbles and running band. The ice friction coefficient at the rear half of a running band is larger than that at the front half because of cooling due to evaporation of pebbles. The asymmetry of the friction force is enhanced by mechanical interactions of ice debris produced by the front running band with the rear band, and result in the curl, or lateral deflection of the stone.The asymmetry is larger, that is the curl distance is larger, at smaller velocity, higher temperature, lower humidity, and larger radius of a running band. However, it is independent of the angular velocity, that is the curl distance does not depend on the total number of rotations.

Comparison between rubber–ice and sand–ice friction and the effect of loose snow contamination

The application of sand particles is a common method to improve the friction of aircraft tires on snow or ice covered runways. Hence, an understanding of the prevailing rubber–ice and sand–ice friction mechanisms is of practical interest. Rubber–ice and sand–ice friction measurements were made with a British Pendulum Tester at temperatures between −22 and 0 °C and the effect of loose snow contamination on top of the ice was investigated. The results (the response of the instrument) were expressed in a sliding length averaged friction coefficient μ BP . Close to the melting point the friction of rubber on ice was low and increased with decreasing ice temperature. Below −5 °C, reasonably high friction levels (0.2< μ BP <0.5) were obtained between rubber and ice, but the friction level dropped drastically by the presence of a very thin layer of snow. The sand–ice friction level was less dependent on ice temperature and clearly not as much affected by the presence of snow, compared to rubber–ice friction. The micromechanisms involved in rubber–ice and sand–ice frictions were investigated by the application of etching and replicating technique (ERT) developed for the examinations of the dynamics of dislocations in ice during deformation.

Microstructural investigation of ice surfaces after rubber–ice and sand–ice sliding friction tests

The dual process of etching and replicating technique revealing lattice dislocations, dislocation cells, grain and sub-grain boundaries, etc., in ice has been applied to investigate the microstructure of freshly deformed ice surfaces after rubber–ice and sand–ice sliding friction tests. Features related to the generation, multiplication and mobility of dislocations were observed in ice subjected to rubber–ice friction even at high speeds and high ice temperatures, involving low friction. During sand–ice friction, deformation took place at the surfaces as well as deeper within the ice by ploughing sand particle, and was accompanied with recrystallization. The deformation features in ice found in the laboratory were also observed in full-scale tire–ice interactions on ice covered runway pavements.

Ocean surface wave evolvement in the Arctic Basin

Recent basin‐scale changes to the compactness and thickness of Arctic sea ice foreshadow that encroaching swells and locally generated waves will exert more influence there in the future. Indeed, it is conceivable that waves may have already hastened the adjustments observed by breaking up ice floes. Yet waves advancing in sea ice attenuate due to being scattered from ice thickness variations and damped by ice inelasticity, turbulence and friction. While past research focuses on scattering by unnaturally perfect features in the ice, the model reported herein assimilates realistic basin‐scale swathes of heterogeneous ice and parameterizes damping. By way of example, we show how an ocean wave train evolves during its passage in an 1670‐km‐long Arctic sea ice profile obtained from submarine.