Frictional forces arise whenever objects around us are set in motion. Controlling them in a rational manner means gaining leverage over mechanical energy losses and wear. This paper presents a way of manipulating nanoscale friction by means of in situ lubrication and interfacial electrochemistry. Water lubricant is directionally condensed from the vapor phase at a moving metal-ionic crystal int...

The melting of an ultrathin lubricant film is studied at friction between atomically flat surfaces. We take into account fluctuations of lubricant temperature, which are defined by the Ornstein-Uhlenbeck process. Phase diagrams and portraits are calculated for secondand first-order transitions (the melting of an amorphous and that of a crystalline lubricants, respectively). It is shown that, in...

This paper presents the results of a laboratory investigation to determine the geotechnical properties of fresh municipal solid waste (MSW) collected from the working phase of Orchard Hills Landfill located in Davis Junction (Illinois, USA). Laboratory testing was conducted on shredded MSW to determine the compaction, hydraulic conductivity, compressibility, and shear strength properties at in-...

Based on an extension of Fenchel inequality, bipotentials are non smooth mechanics tools, used to model various non associative multivalued constitutive laws of dissipative materials (friction contact, soils, cyclic plasticity of metals, damage). Let X , Y be dual locally convex spaces, with duality product 〈·, ·〉 : X×Y → R. Given the graph M ⊂ X × Y of a multivalued law T : X → 2 , we state a ...

The regularity of a solution to the variational inequality for the Stokes equation is considered. The inequality describes the steady motion of the viscous incompressible uid under a certain unilateral constrain of friction type. Firstly the solution is approximated by solutions to a regularized problem which is introduced by Yosida's regularization for a multi-valued opearator. Then we establi...

Friction is a well-known, but poorly understood, phenomenon that affects virtually all aspects of daily life. In some cases, friction is desirable, e.g., high friction in clutches leads to the effective transmission of forces between an automobile’s engine and its wheels, while in other cases friction is a significant drawback, e.g., friction between the piston and cylinder wall decreases the e...

LuGre friction model is an ordinary differential equation that is widely used in describing the friction phenomenon for mechanical systems. The importance of this model comes from the fact that it captures most of the friction behavior that has been observed including hysteresis. In this paper, we study some aspects related to the hysteresis behavior induced by the LuGre friction model.

Friction plays a key role in how ruptures unzip faults in the Earth's crust and release waves that cause destructive shaking. Yet dynamic friction evolution is one of the biggest uncertainties in earthquake science. Here we report on novel measurements of evolving local friction during spontaneously developing mini-earthquakes in the laboratory, enabled by our ultrahigh speed full-field imaging...

Friction plays an important role in the behavior of flowing granular media. The effective friction coefficient is a description of shear strength in both slow and rapid flows of these materials. In this paper, we study the steady state effective friction coefficient μ in a granular material in two steps. First, we develop a new relationship between the steady state effective friction coefficien...

In this paper, an adaptive robust control (ARC) scheme based friction compensation strategy is presented for a class of mechanical systems in the presence of dynamic friction effects. In contrast to existing deterministic robust control (DRC) and adaptive control (AC) schemes, the proposed ARC scheme utilizes both the structural information of the dynamic friction model and the available prior ...