We study static packings of frictionless and frictional spheres in three dimensions, obtained via molecular dynamics simulations, in which we vary particle hardness, friction coefficient, and coefficient of restitution. Although frictionless packings of hard spheres are always isostatic (with six contacts) regardless of construction history and restitution coefficient, frictional packings achie...

Article history: Received 6 October, 2015 Accepted 7 March 2016 Available online 8 March 2016 Dry friction depends on the surface topography which, in turn, is governed by machining parameters in addition to several other factors,. Therefore, in order to establish a qualitative relationship among these factors, the surface roughness and coefficient of static friction are measured for specimens ...

A new dynamic friction force model for the longitudinal road/tire interaction for wheeled ground vehicles is validated via experiments with an actual passenger vehicle. Contrary to common static friction/slip maps, this new dynamic friction model is able to accurately capture the transient behavior of the friction force observed during transitions between braking and acceleration. A velocitydep...

A new generation of experiments on dry macroscopic friction has revealed that the transition from static to dynamic friction is essentially a spatially and temporally non-uniform process, initiated by a rupture-like detachment front. We show the suitability of the FrenkelKontorova model for describing this transition. The model predicts the existence of two types of detachment fronts, explainin...

in order to provide the data needed for the design of saffron processing equipment, physical properties of its flower were investigated. these properties included dimensions, mass, true and bulk densities, porosity, static and dynamic coefficients of friction, and terminal velocity as a function of moisture content. the average range of these properties for the three different parts of saff...

In rehabilitation training, high-fidelity simulation environments are needed for reproducing the effects of slippery surfaces, in which potential balance failure conditions can be reproduced on demand. Motivated by these requirements, this article considers the design of variable-friction devices for use in the context of human walking on surfaces in which the coefficient of friction can be con...

In many sliding systems consisting of solid object on a solid substrate under dry condition, the friction force does not depend on the apparent contact area and is proportional to the loading force. This behaviour is called Amontons' law and indicates that the friction coefficient, or the ratio of the friction force to the loading force, is constant. Here, however, using numerical and analytica...

The theory of stick-slip is developed, based on the concept of a static and dynamic coefficient of friction. The dynamic coefficient is assumed to be independent of displacement and to depend wholly on normal stress across the surface. It is also assumed to be velocity-independent. The theory predicts that the stress drop during stick-slip is independent of machine stiffness. The displacement d...

A quasi-static contact problem is considered for a non-linear elastic system with finitely many degrees of freedom. Coulomb’s law is used to model friction and the friction coefficient may be anisotropic and may vary along the surface of the rigid obstacle. Existence is established following a time-incremental minimization problem. Friction is artificially decreased to resolve the discontinuity...

The friction of surfaces moving relative to each other must derive from the atomic interaction at interfaces. However, recent experiments bring into question the fundamental understanding of this phenomenon. The analytic theories predict that most perfect clean incommensurate interfaces would produce no static friction, whereas commensurate aligned surfaces would have very high friction. In con...