An experiment is conducted in which a free-standing bicycle wheel is given an initial angular speed and then allowed to slow down to rest. Measurements of the wheel speed, using a magnetic sensor, during the decay are compared to predictions from a model accounting for a combination of viscous and dry friction at the wheel bearing. The time history data indicate two dynamic regimes: (i) a highe...

We generalize a model for friction at a sliding interface involving the motion of misfit dislocations to include the effect of thermally activated transitions across barriers. We obtain a comparatively simple form with the absolute zero-temperature Peierls barrier replaced by an effective Peierls barrier which varies exponentially with temperature, in agreement with recent experimental observat...

Our walking and running movement patterns require friction between shoes and ground. The surface of ice is characterized by low friction in several naturally occurring conditions, and compromises our typical locomotion pattern. Ice skates take advantage of this slippery nature of ice; the first ice skates were made more than 4,000 years ago, and afforded the development of a very efficient form...

When two macroscopic bodies in contact slide, energy is dissipated. However, at the nanoscale, tiny amounts of energy can also be dissipated when the sliding bodies are not in contact with each other. Such non-contact form of friction — the origin of which has been associated with van der Waals (vdW) forces — has been measured with highly sensitive atomic force microscopy (AFM). In a friction f...

[1] We investigate fault friction from dynamic modeling of fault slip prior to and following the Mw 6.0 earthquake which ruptured the Parkfield segment of the San Andreas Fault in 2004. The dynamic modeling assumes a purely rate-strengthening friction law, with a logarithmic dependency on sliding rate: m 1⁄4 m þ a b ð Þ ln v v . The initial state of stress is explicitly taken into account, and ...

AIM Compare surface roughness of 'aesthetic' nickel-titanium (NiTi) archwires with their dynamic frictional properties. METHODS Archwires investigated were: four fully coated tooth coloured [Forestadent: Biocosmetic (FB) and Titanol Cosmetic (FT); TOC Tooth Tone (TT); and Hawley Russell Coated Superelastic NiTi (HRC)]; two partially coated tooth coloured [DB Euroline Microcoated (DB) and TP A...

snake robots are hyper-redundant robots that are connected with one or two dof joints. they offer a number of potential advantages beyond the capabilities of most wheeled and legged robots. in this paper, kinematics and dynamics of a planar multi-link snake robot in worm-like locomotion on an inclined surface is investigated. in this locomotion, snake robot is able to move in the vertical plane...

The paper describes results obtained from plate-impact pressure-shear friction experiments to investigate the phenomena of high-speed slip at metal-on-metal interfaces. Using a CH toolsteel/Ti-6Al-4V tribo-pair the authors have studied the effects of normal pressure, slip-speed, temperature and surface roughness on the evolution of the dynamic slip-resistance. Moreover, a finite-element procedu...

Studies of the power-law relations of seismicity and earthquake source parameters based on the one-dimensional (1-D) Burridge-Knopoff’s (BK) dynamical lattice model, especially those studies conducted by Taiwan’s scientists, are reviewed in this article. In general, velocityand/or state-dependent friction is considered to control faulting. A uniform distribution of breaking strengths (i.e., the...