Normal stress dependence of ice-ice friction coefficients.

Abstract

The ice-ice friction coefficient was measured as a function of normal stress (1.217.3 kPa), temperature (-0.5-20°C) and velocity (4×10-3, 4.5×10-2, 4×10-1m/s). The friction coefficient was found to decrease with increasing normal stress and became almost constant at larger normal stresses than about 6 kPa at all the temperatures and velocities studied. Though the overall dependence could be expressed as, μ ∝ P-0.32 where μ and P are respectively the ice-ice friction coefficient and normal stress, the Mohr-Coulomb relation, μ=μO+A/P, was utilized in our data analysis, where μO and A are the Coulomb friction coefficient and adhesion strength, respectively. The temperature dependence of μO showed a minimum around-5°C. The value of μO decreased with increasing velocity, suggesting the formation of water film by friction heat at these low sliding velocities. The value of adhesion strength was of the order of 10250 Pa and increased with lowering temperature or increasing velocity.