3 research outputs found
Oscillating Friction on Shape-Tunable Wrinkles
Friction on soft materials is strongly
correlated with the associated deformation, which may be controlled
by the surface topography. We investigate the wearless sliding friction
between a rigid hemispherical indenter and a deformable textured surface,
which is shape-tunable wrinkles. The size of the indenter is comparable
to the wavelength of the wrinkles. We evaluate the effects on the
friction of the aspect ratio of the wrinkles, the applied normal load,
and the alignment direction of the wrinkles relative to the sliding
direction. The frictional oscillations are observed during sliding
in the direction perpendicular to the alignment using optical images
and friction profiles. The correlation of friction force oscillation
with deformation of the wrinkles is elucidated using Hertz contact
theory. Within a cycle of frictional oscillation, the friction force
increases as the front part of the indenter elastically plows the
crests. When the normal load is high and/or the aspect ratio of the
wrinkles is low, the indenter continues to squash the wrinkles and
remains in contact with them during sliding. Consequently, the amplitude
of friction force oscillation relative to the averaged friction force
decreases