A European scientist has presented an explanation for the origin of sliding friction between solid objects.
An experiment to demonstrate static and sliding friction. They are compared using a sled containing lead bricks. The sled is pulled with the scale until the sled begins to move. The maximum force needed to overcome the static friction and begin the sled moving is noted. The sled is then pulled at a constant velocity and the sliding friction measurement is noted (University of Illinois at Urbana-Champaign)
Friction is a key phenomenon in applied physics, whose origin has been studied for centuries.
Until now, it has been understood that mechanical wear-resistance and fluid lubrication affect friction, but the fundamental origin of sliding friction has been unknown.
Dr Lasse Makkonen, principal scientist at VTT Technical Research Center in Finland has now presented an explanation for the origin of sliding friction between solid objects.
According to his theory, described in a paper in the journal AIP Advances, the amount of friction depends on the surface energy of the materials in question.
Friction has a substantial effect on many everyday phenomena, such as energy consumption.
The new thermodynamic model is the first to enable quantitative calculation of the friction coefficient of materials.
The amount of friction is related to the material’s surface energy, according to the new theory.
Friction originates in nanoscale contacts, as the result of new surface formation. The theory explains the generation of frictional force and frictional heating in dry contact. It can be applied in calculating the friction coefficient of various material combinations.
The model also enables the manipulation of friction by selecting certain surface materials or materials used in lubrication layers, on the basis of the surface energy between them.
