Rolling and sliding: Separation of adhesion and deformation friction and their relative contribution to total friction

• Adhesion and deformation friction separated using rolling and sliding method.
• A substrate used that mimics the viscoelastic behaviour and surface texture of human skin.
• The relative proportion of adhesion and deformation friction to total friction significantly affected by lubrication.
• Deformation friction should not be ignored in application where high normal loads and speed are used on human skin.

This study is concerned with determining the relative contribution of adhesion and deformation friction using rolling and sliding method. The challenges associated with in-vivo friction testing were overcome by utilising a novel substrate that mimics the viscoelastic behaviour and surface texture of human skin combined with a repeatable and reproducible test setup. The results show that in the dry state, deformation friction contributes 20% of the total friction while the remaining proportion is due to adhesion. These proportions are affected by probe material where for PTFE, deformation friction contributes 30% of the total friction. For the lubricated state, the contribution of deformation friction to total friction increases approaching 50–50% at the higher sliding speeds and normal loads investigated.