This work presents a finite element study of elasto-plastic hemispherical contact. The results are normalized such that they are valid for macro contacts (e.g., rolling element bearings) and micro contacts (e.g., asperity contact). The material is modeled as elastic-perfectly plastic. The numerical results are compared to other existing models of spherical contact, including the fully plastic c...

In a spirit akin to the sandpile model of selforganized criticality, we present a simple statistical model of the cellular-automaton type which simulates the role of an asperity in the dynamics of a one-dimensional fault. This model produces an earthquake spectrum similar to the characteristic-earthquake behaviour of some seismic faults. This model, that has no parameter, is amenable to an alge...

Based on focused ion beam and shear friction apparatus data, the multi-resolutions (0.2 nm–5 μm) volume roughness & asperity contact (VR & AC) three-dimensional structure on principle slip surface interface-surface (PSS-IS) is measured on high performance computational platform; and physical plastic-creep friction model is established by using hybrid hyper-singular integral equation & lattice B...

The authors report the direct observation of a single asperity tungsten tip sliding on graphite by in situ transmission electron microscopy TEM nanomanipulation. The in situ TEM studies have confirmed that graphitic flakes transfer to a sliding tungsten probe, validating proposed friction mechanisms explaining the unique tribological properties of graphite. Wear of graphite was observed, typica...

Abstract The approach of two spheres along their line of centres is analyzed assuming that each sphere is covered by a porous layer. The slip of the fluid at the surface of the porous layers then permits the spheres to touch without a singularity in the associated force. In a corresponding analysis for flat surfaces, an analytical formula for the force is obtained. This force is also finite for...

Mechanisms of energy dissipation during solid-solid and solid-liquid friction are discussed. A conservative van der Waals adhesion force, when combined with surface imperfectness, such as deformation, leads to adhesion hysteresis (AH). When an asperity slides upon a substrate, the substrate is subjected to a loading-unloading cycle, and energy is dissipated due to the AH. Another mechanism, whi...

A new phenomenon, anomalous increase of static friction in the vicinity of atomic defects, is studied by means of molecular simulations. It is found that an apex of a single asperity contact becomes “trapped” in the vicinity of a defect provided the normal force acting between the apex and surface is above some critical value. Examples of an atomic vacancy and a step are analyzed. The anomaly i...

In the present study, empirical attenuation relations for multiple ground motion intensity measures (PGA, PGV, Ia, FIV3, CII, and MFAS) were developed Sakhalin Island (in far east of Russia). A recorded strong dataset was used, making GMPEs applicable in active crustal regions with an earthquake magnitude range 4–6 a distance up to 150 km. The hypocentral used as basic metric. For first time re...