How the contact behaviours of steel engineering surfaces with different roughnesses ( R a = 0.1, 0.6 and 1.0 μm) are affected by asperity work-hardening deformation regime described here. Large values plasticity index Ψ between 20 50 indicate that all should undergo full plastic deformation. However, in loading range up to yield stress (on nominal area) rough exhibited at least 10% elastic defo...

three-dimensional surface geometry of rock discontinuities and its evolution with shearing are of great importance in understanding the deformability and hydro-mechanical behavior of rock masses. in the present research, surfaces of three natural rock fractures were digitized and studied before and after the direct shear test. the variography analysis of the surfaces indicated a strong non-line...

Numerical models of earthquake rupture are used to investigate characteristic length scales and size distributions of repeated earthquakes on vertical, planar fault segments. The models are based on exact solutions of static three-dimensional (3-D) elasticity. Dynamical rupture is approximated by allowing the static stress field to expand from slip motions at a single velocity. To show how the ...

This paper analyses the problem of modelling joint friction in robotic manipulators with gear transmissions at joint velocities varying from close to zero until their maximum appearing values. It is shown that commonly used friction models that incorporate Coulomb, (linear) viscous and Stribeck components are inadequate to describe the friction behaviour for the full velocity range. A new frict...

[1] Recent results from laboratory experiments on a broad range of mineral systems exhibit dramatic drops in the effective friction coefficient m once the slip rate exceeds a critical level Vw, which is typically O(0.1) m/s. This ‘‘flash weakening’’ has been attributed to the effects of localized heating at highly stressed microscopic asperities. We extend previous phenomenological treatments t...

The thermal asperity (TA) defect resulting from the collision between an asperity and the magneto-resistive (MR) read head can distort the readback signal to the extent of causing possible sector read failure. This paper presents a new TA detection and correction algorithm for perpendicular recording channels. The proposed algorithm consists of two channels running in parallel, one for the H1(D...