Amontons Laws

The two Amontons laws form the basis of the empirical understanding of tribology (theory of friction of solid bodies). They are named after Guillaume Amontons (1663–1705), who rediscovered them in 1699. The real discoverer was, about two hundred years earlier, Leonardo da Vinci (1452–1519).

The term Amonton's Laws is not generally used, especially not in older literature. They are often subsumed under the Coulomb friction laws formulated later by Charles Augustin de Coulomb . More precisely, the Coulomb laws also include the statement that the force caused by static friction has a maximum value, expressed by the coefficient of static friction and the force with which the body and base press against each other at right angles to the contact surface: and that the coefficient of static friction is higher than the coefficient of sliding friction . With greater shear force, sliding begins. ${\ displaystyle F_ {H}}$ ${\ displaystyle \ mu _ {0}}$ ${\ displaystyle F_ {N}}$ ${\ displaystyle F_ {H} \ leq \ mu _ {0} \ cdot F_ {N}}$ ${\ displaystyle \ mu _ {0}}$ ${\ displaystyle \ mu}$

Laws

1st law:

The maximum static friction force and the friction force when sliding are independent of the expansion of the friction surface.

2nd law:

The friction forces are directly proportional to the normal or contact force between the friction surfaces (pressing force) . ${\ displaystyle F_ {N}}$

With a proportionality factor , the coefficient of friction , which depends on the material pairing and the intermediate material (e.g. lubricant ) : ${\ displaystyle \ mu}$

{\ displaystyle F = \ mu \ cdot F_ {N}}

It should be noted that the second law describes the behavior of most metals with lubricated and unlubricated sliding friction, but not the behavior of the majority of polymers .

Individual evidence

↑ Peter Blau: Amontons law of friction , in Wang, Chung (ed.), Encyclopedia of Tribology , Springer 2013, p. 71, excerpt
↑ Westphal, Physik , Springer 1970, p. 49
↑ K. Magnus, Müller: Technische Mechanik , Teubner 1990, p. 77
↑ Szabo, Introduction to Technical Mechanics , Springer 1956, p. 257

[1] Peter Blau: Amontons law of friction , in Wang, Chung (ed.), Encyclopedia of Tribology , Springer 2013, p. 71, excerpt

[2] Westphal, Physik , Springer 1970, p. 49

[3] K. Magnus, Müller: Technische Mechanik , Teubner 1990, p. 77

[4] Szabo, Introduction to Technical Mechanics , Springer 1956, p. 257