Even though friction affects everyday life in many ways, it is still one of the biggest mysteries of physics. Friction is a truly multi-scale phenomenon with a large variety of processes acting at various length and time scales. In recent years, much attention was paid to the microand nano-scale properties of frictional interfaces in order to uncover the origins of friction. The structural aspe...

In this study, a limit equilibrium method has been developed that satisfies all conditions of equilibrium and assumes circular slip surfaces. All force and moment equilibrium equations are employed without using simplification assumptions. A non-linear optimization technique is used to solve the system of equations with the corresponding constraints. The proposed method is capable to determine ...

[1] For a wide range of conditions, earthquake nucleation zones on rateand statedependent faults that obey either of the popular state evolution laws expand as they accelerate. Under the ‘‘slip’’ evolution law, which experiments show to be the more relevant law for nucleation, this expansion takes the form of a unidirectional slip pulse. In numerical simulations these pulses often tend to appro...

We perform numerical simulations of a shear flow over a periodically patterned substrate with entrapped gas bubbles. A diffuse-interface model is employed to handle the liquid-gas interface deformation and the three-phase contact line. Depending on the shear rate and the pattern geometry, four flow regimes are observed. The contact lines can be pinned, depinned, or eliminated depending on the c...

Far-field high-energy X-ray diffraction microscopy is used to asses the evolution of slip system strengths in hexagonal close-packed (HCP) Ti-7Al during tensile deformation in-situ. The following HCP slip system families are considered: basal 〈a〉, prismatic 〈a〉, pyramidal 〈a〉, and first-order pyramidal 〈cþ a〉. A 1 mm length of the specimen's gauge section, marked with fiducials and comprised of...

Response surface methodology with Box–Benhken (BB) design of experiment approach has been utilized to study the mechanism of interface slip damping in layered and jointed tack welded beams with varying surface roughness. The design utilizes the initial amplitude of excitation, tack length and surface roughness at the interfaces to develop the model for the logarithmic damping decrement of the l...

Rapid advances in microelectromechanical systems have stimulated the development of compact devices, which require effective cooling technologies (e.g., microchannel cooling). However, the inconsistencies between experimental and classical theoretical predictions for the liquid flow in microchannel remain unclarified. Given the larger surface/volume ratio of microchannel, the surface effects in...

We present in this Letter an experimental characterization of liquid flow slippage over superhydrophobic surfaces made of carbon nanotube forests, incorporated in microchannels. We make use of a particle image velocimetry technique to achieve the submicrometric resolution on the flow profile necessary for accurate measurement of the surface hydrodynamic properties. We demonstrate boundary slipp...

A formalism is presented which predicts the influence of laterally heterogeneous slip (for instance, induced by nanoscopic air bubbles) on the shift of the resonance frequency and bandwidth of quartz crystal resonators immersed in liquids. The lateral heterogeneities are decomposed into their Fourier components. The distribution of slip lengths provides a boundary condition, giving rise to a sm...

We propose the rarefied-gas-cushion model (r-GCM), as an extended version of the gas-cushion model (GCM), to estimate the apparent slip of water flowing over a gas layer trapped at a solid surface. Nanobubbles or gas nanofilms may manifest rarefied-gas effects and the r-GCM incorporates kinetic boundary conditions for the gas component in the slip Knudsen regime. These enable an apparent hydrod...