Local friction at a sliding interface between an elastomer and a rigid spherical probe.

Area of Science:

• Tribology
• Materials Science
• Surface Physics

Background:

• Understanding friction at interfaces is crucial for material design and performance.
• Previous models often assume uniform shear stress, which may not hold true for real-world surfaces.

Purpose of the Study:

• To spatially resolve shear stress distribution at a rubber-glass frictional interface.
• To investigate the effect of surface roughness on shear stress profiles.
• To challenge existing friction models based on contact area and uniform shear stress.

Main Methods:

• Prepared silicone rubber specimens with surface patterns.
• Measured surface displacement fields using optical methods under steady-state friction.
• Deconvolved displacement fields to determine shear stress distribution.

Main Results:

• Smooth glass lenses resulted in nearly constant shear stress within the contact area.
• Rough glass lenses produced a bell-shaped shear stress distribution.
• Observed variations in local friction with roughness could not be explained by simple contact area or constant shear stress assumptions.

Conclusions:

• Surface roughness significantly alters the shear stress distribution at rubber-glass interfaces.
• The findings necessitate a re-evaluation of friction models that rely on simplified assumptions about contact mechanics.
• Further research is needed to develop more accurate models for predicting friction behavior across varied surface topographies.