Friction of ice on ice

Abstract

[1] New measurements have been made of the friction coefficient of freshwater polycrystalline ice sliding slowly (5 Â 10 À8 to 1 Â 10 À3 m s À1) upon itself at temperatures from 98 to 263 K under low normal stresses (≤98 kPa). Sliding obeys Coulomb's law: the shear stress is directly proportional to the normal stress across the interface, while cohesion offers little contribution to frictional resistance. The coefficient of kinetic friction of smooth surfaces varies from m k = 0.15 to 0.76 and, at elevated temperatures (≥223 K), exhibits both velocity strengthening at lower velocities (<10 À5 to 10 À4 m s À1 ) and velocity weakening at higher velocities. Strengthening and weakening are attributed to creep deformation of asperities and localized melting, respectively. At intermediate temperatures of 173 and 133 K, the kinetic coefficient appears to not exhibit significant dependence upon velocity. However, at the low temperature of 98 K the coefficient of kinetic friction exhibits moderate velocity strengthening at both the lowest and the highest velocities but velocity independence over the range of intermediate velocities. No effect was detected of either grain size or texture. Over the range of roughness 0.4 Â 10 À6 m ≤ R a ≤ 12 Â 10 À6 m, a moderate effect was detected, where m k ∝ R a 0.08 . Slide-hold-slide experiments revealed that the coefficient of static friction increases by an amount that scales logarithmically with holding time. Implications of the results are discussed in relation to shearing across "tiger stripe" faults within the icy crust of Saturn's Enceladus, sliding of the arctic sea ice cover and brittle compressive failure of cold ice.

Multi-method observation and analysis of a tsunami caused by glacier calving

“…With an initial center-of-mass elevation of z = 100 m (half the ice front height), a slope α = 45 • , and a friction coefficient of f = 0.2-0.1, the impact velocity is v s = 39-42 m s −1 . This choice of the friction parameter is motivated by studies of dynamic friction of ice on ice at high temperature and speed (Schulson and Fortt, 2012). An independent estimate of the ice slide impact velocity can be gained directly from analysis of the video.…”

Atomistic simulations of friction at an ice-ice interface

“…Friction plays a critical role in both terrestrial and extraterrestrial ice mechanics [1]. Examples include fracture of the Arctic sea ice cover [2][3][4][5][6][7][8][9][10][11][12], brittle compressive failure during interactions between natural ice features and engineered structures [13,14], and tectonic activity of ice-encrusted bodies within the outer solar system [15][16][17][18][19][20][21][22][23][24].…”

Multiscale physics of rubber-ice friction

“…In addition, there may be an increased friction at the start-up of the sliding resulting from an increase in the area of real contact during the time of stationary contact (dwell time 2 s) as a result of thermally activated creep processes. [31][32][33][34] Similar physical processes may explain the peak in the friction observed for the sliding speed v ≈ 0.11 m/s. Finally, for the highest sliding speed v ≈ 0.94 m/s, the melting of the ice will already take place after a sliding distance of the order of 1 mm.…”