17,632 research outputs found
Rubber friction on (apparently) smooth lubricated surfaces
We study rubber sliding friction on hard lubricated surfaces. We show that
even if the hard surface appears smooth to the naked eye, it may exhibit short
wavelength roughness, which may give the dominant contribution to rubber
friction. That is, the observed sliding friction is mainly due to the
viscoelastic deformations of the rubber by the substrate surface asperities.
The presented results are of great importance for rubber sealing and other
rubber applications involving (apparently) smooth surfaces.Comment: 7 pages, 15 figure
Contact mechanics with adhesion: Interfacial separation and contact area
We study the adhesive contact between elastic solids with randomly rough,
self affine fractal surfaces. We present molecular dynamics (MD) simulation
results for the interfacial stress distribution and the wall-wall separation.
We compare the MD results for the relative contact area and the average
interfacial separation, with the prediction of the contact mechanics theory of
Persson. We find good agreement between theory and the simulation results. We
apply the theory to the system studied by Benz et al. involving polymer in
contact with polymer, but in this case the adhesion gives only a small
modification of the interfacial separation as a function of the squeezing
pressure.Comment: 5 pages, 4 figure
Contact mechanics: relation between interfacial separation and load
I study the contact between a rigid solid with a randomly rough surface and
an elastic block with a flat surface. I derive a relation between the (average)
interfacial separation and the applied normal squeezing pressure . I
show that for non-adhesive inte raction and small applied pressure, p is
proportional to exp (-u/u_0), in good agreement with recent experimental
observation.Comment: 4 pages, 3 figure
Influence of frozen capillary waves on contact mechanics
Free surfaces of liquids exhibit thermally excited (capillary) surface waves.
We show that the surface roughness which results from capillary waves when a
glassy material is cooled below the glass transition temperature can have a
large influence on the contact mechanics between the solids. The theory suggest
a new explanation for puzzling experimental results [L. Bureau, T. Baumberger
and C. Caroli, arXiv:cond-mat/0510232] about the dependence of the frictional
shear stress on the load for contact between a glassy polymer lens and flat
substrates. It also lend support for a recently developed contact mechanics
theory.Comment: 4 pages, 2 figure
Interfacial separation between elastic solids with randomly rough surfaces: comparison of experiment with theory
We study the average separation between an elastic solid and a hard solid
with a nominal flat but randomly rough surface, as a function of the squeezing
pressure. We present experimental results for a silicon rubber (PDMS) block
with a flat surface squeezed against an asphalt road surface. The theory shows
that an effective repulse pressure act between the surfaces of the form p
proportional to exp(-u/u0), where u is the average separation between the
surfaces and u0 a constant of order the root-mean-square roughness, in good
agreement with the experimental results.Comment: 6 pages, 10 figure
Rolling friction for hard cylinder and sphere on viscoelastic solid
We calculate the friction force acting on a hard cylinder or spherical ball
rolling on a flat surface of a viscoelastic solid. The rolling friction
coefficient depends non-linearly on the normal load and the rolling velocity.
For a cylinder rolling on a viscoelastic solid characterized by a single
relaxation time Hunter has obtained an exact result for the rolling friction,
and our result is in very good agreement with his result for this limiting
case. The theoretical results are also in good agreement with experiments of
Greenwood and Tabor. We suggest that measurements of rolling friction over a
wide range of rolling velocities and temperatures may constitute an useful way
to determine the viscoelastic modulus of rubber-like materials.Comment: 7 pages, 6 figure
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