The peak of smooth Fourier amplitude spectra, (FS(T))max, of strong motion acceleration recorded in California is modeled via dimensional analysis. In this model, the spectrum amplitudes are proportional to (1) – the root-mean-square (r.m.s.) amplitude of the peak stresses on the fault surface in the areas of high stress concentration (asperities), and (2) (log10 N)1/2, where N is the number of...

Phosphorus L-edge and oxygen K-edge X-ray PhotoEmission Electron Microscopy (XPEEM) have been used to characterize the chemical nature of the cation present in tribochemical films via comparison with model Fe and Zn compounds. The results are contrasted to the P L-edge, P K-edge and S K-edge XANES data. The findings suggest that antiwear pads containing long chain zinc polyphosphate glass are f...

Friction is a complicated phenomenon involving nonlinear dynamics at different length and time scales. Understanding its microscopic origin requires methods for measuring force on nanometer-scale asperities sliding at velocities reaching centimetres per second. Despite enormous advances in experimental technique, this combination of small length scale and high velocity remain elusive. We presen...

We present a 3D adhesion model based on the JKR theory applied locally for all contacting asperity couple and the calculations account the van der Waals interaction beside the externally applied force. Thus, equilibrium of the system is determined by an extremum in the free total energy and subsequently the contact and the adhesion parameters are computed for that particular position. The model...

[1] The ground motion data of the 1999 Chi-Chi, Taiwan, earthquake exhibit a striking difference in frequency content between the north and south portions of the rupture zone. In the north, the ground motion is dominated by large lowfrequency displacements with relatively small high-frequency accelerations. The pattern is opposite in the south,with smaller displacements and larger accelerations...

Micro flexible rolling aims to fabricate submillimeter thick strips with varying thickness profile, where the surface quality of products is mainly determined by initial workpiece surface roughness and subsequent surface asperity flattening process, which is affected by process parameters during rolling. This paper shows a 3D finite element model for flexible rolling of a 250 μm thick workpiece...

A micro-mechanical dislocation model of frictional slip between two asperities was presented by Hurtado and Kim [1], which predicts that the friction stress is constant and of the order of the theoretical shear strength, when the contact size is small. However, at a critical contact size there is a transition beyond which the frictional stress decreases with increasing contact size, until it re...

Abstract Fault surfaces are characterized by an inhomogeneous friction distribution, that can be represented with asperity models. mechanics is dominated asperities, so a fruitful approach to use discrete models, where asperities the basic elements and state of fault described average values stress, slip on each asperity. Under reasonable assumptions, equations motion solved analytically, deepe...