Space-time finite element methods for dynamic frictional contact problems are discussed in this article. The discretization scheme is based on a mixed formulation of the continuous problem, where the Lagrange multipliers represent the contact and frictional stresses. Using piecewise d-linear and globally continuous basis functions in space and time to construct the trial space for the displacem...

C60-terminated self-assembled monolayers (SAMs) were generated on the surface of Au(111) by the adsorption of unsymmetrical disul®des having saturated hydrocarbon backbone structures comprised of six (C-6) and eleven (C-11) carbon atoms. The formation of oriented monolayer ®lms from these adsorbates was con®rmed by ellipsometric thickness and contact angle measurements. The morphologies and fri...

The process by which sheared suspensions go through a dramatic change in viscosity is known as discontinuous shear thickening. Although well-characterized on the macroscale, the microscopic mechanisms at play in this transition are still poorly understood. Here, by developing new experimental procedures based on quartz-tuning fork atomic force microscopy, we measure the pairwise frictional prof...

the object of this work is to present a study of the thermomechanical behavior of the automobile disc brake for the prediction of their resistance to fatigue. then, a study of purely mechanical dry contact between the disc and pads is developed with a good prediction becomes a major stake for the industrialists while modeling the loading and the boundary conditions around the disc.we used the s...

This paper represents a continuation of [1] and [2]. Here, we consider the numerical analysis non-trivial frictional contact problem in form system evolution nonlinear partial differential equations. The model describes equilibrium viscoelastic body sliding with moving foundation. is modeled multivalued normal compliance condition memory term restricted by unilateral constraint associated versi...

We report on the frictional properties of a single contact between a glassy polymer lens and a flat silica substrate covered either by a disordered or by a self-assembled alkylsilane monolayer. We find that, in contrast to a widely spread belief, the Amontons proportionality between frictional and normal stresses does not hold. Besides, we observe that the velocity dependence of the sliding str...

We present an alternative way to determine the frictional forces at the contact between two particles. This alternative approach has its motivation in a detailed analysis of the bounds on the time integration step in Discrete Element Method (DEM) for simulating collisions and shearing of granular assemblies. We show that, in standard numerical schemes, the upper limit for the time integration s...

This paper aims to provide an understanding of the intrinsic frictional behaviour of CNTs under contact sliding by eliminating the possible effects of CNT rolling and slipping. Two critical steps towards the mechanism exploration were carried out: (1) the development of a new deposition method for CNT film fabrication, which allows the manufacture of densely packed, highly entangled CNT films t...

In greased contacts, the complex rheology of a grease, depending on thickener, base oil and additives, becomes key point for understanding controlling evolution friction coefficient at extremely low sliding velocities. Such velocity range (from 0 to few mm/s) is main relevance several issues, such as unstable friction-induced vibrations, which can occur well in case lubricated interfaces. this ...

Slip, especially incipient slip, is a complicated process for soft fingertips; and detection of this slip is important for stable manipulations by both human and robotic fingertips. Experimental research has attempted to explain this phenomenon, but dynamic changes during this process could not be fully delineated. We propose here a dynamic model to investigate the sliding motion of soft finger...