The pH-responsive frictional behavior of layer-by-layer assembled poly(allylamine hydrochloride) and poly(acrylic acid) multilayers is quantified in different geometric forms of a continuous planar film and anisotropic tube forests. A mechanistic change from surface adhesion dominated frictional behavior to visco/poroelasticity-governed shear occurs for the planar film upon pH-stimulus. This pH...

[1] Faulting and brittle deformation of mantle rocks occurs in many tectonic settings such as oceanic transform faults, oceanic detachment faults, subduction zones, and continental rifts. However, few data exist that directly explore the frictional properties of peridotite rocks. Improved constraints on the brittle deformation of peridotite is important for a more complete understanding of the ...

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...

An investigation into the properties of granular materials is undertaken via numerical simulation. These simulations highlight that frictional contact, a defining characteristic of dry granular materials, and interfacial debonding, an expected deformation mode in plastic bonded explosives, must be properly modeled. Frictional contact and debonding algorithms have been implemented into FLIP, a p...

The aim of this study was to compare frictional resistance among conventional, passive and active selfligating brackets using Finite Elements Analysis (FEA). Seventynine (79) slide tests were performed by combining an upper first bicuspid conventional bracket, 0.018" stainless steel wires and 0.010" ligature by means of an INSTRON 3345 load system to obtain average maximum static frictional res...

Amorphous packings of frictionless, spherical particles are isostatic at jamming onset, with the number of constraints (contacts) equal to the number of degrees of freedom. Their structural and mechanical properties are controlled by the interparticle contact network. In contrast, amorphous packings of frictional particles are typically hyperstatic at jamming onset. We perform extensive numeric...

INTRODUCTION The majority of current artificial hip implants use a material combination of ultra-high molecular-weight polyethylene against metal or ceramic. However, it is well documented that the wear debris from these prostheses contributes to osteolysis and ultimate failure of the prosthesis, hence alternative materials have been sought, such as metalon-metal and ceramic-on-ceramic [1]. Mor...

The critical rheology of sheared frictional granular materials near jamming transition is numerically investigated. It is confirmed that there exists a true critical density which characterizes the onset of the yield stress and two fictitious critical densities which characterize the scaling laws of rheological properties. We find the existence of a hysteresis loop between two of the critical d...

The field of tribology defined in Webster’s Dictionary as “a science that deals with the design, friction, wear and lubrication of interacting surfaces in relative motion” has a long and important history in science and technology[1]. The ancient Egyptians, for example, used water to lubricate the path of sleds employed to transport extremely heavy objects. The first scientific studies of frict...