Abstract
The authors realized reciprocating-sliding friction tests by using different type of contacting surfaces such as steel ball on steel plate, steel cylinder and glass on finger skin in dry and lubricated conditions. The experimental tests put in evidence the transient regime of the tangential force and relative velocity. In case of steel-on-steel contact the transition of tangential force shows almost the same trend as the relative velocity. For the sliding friction between steel-on-skin and glass-on-skin it was observed that the tangential force showed a time delay when pass from positive to negative values compared to velocity. The time period in which tangential force pass through zero is depending on the viscoelastic properties of the finger skin. Experimental results were validated with a simplified model based on Heaviside step function and showed a good correlation, especially for the lubricated sliding contact. The proposed methodology gives satisfactory results only if the tangential friction force is varying symmetrically in the transient sliding friction process.