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The two regimes of dry friction are 'static friction' ("stiction") between non-moving surfaces, and kinetic friction (sometimes called sliding friction or dynamic friction) between moving surfaces. Coulomb friction, named after Charles-Augustin de Coulomb , is an approximate model used to calculate the force of dry friction.
Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation (or movement) of the wheel, roadbed, etc., is recovered when the pressure is removed.
Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface. It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation (or movement) of the wheel, roadbed, etc., is recovered when the pressure is removed.
Stiction (a portmanteau of the words static and friction) [1] is the force that needs to be overcome to enable relative motion of stationary objects in contact. [2] Any solid objects pressing against each other (but not sliding) will require some threshold of force parallel to the surface of contact in order to overcome static adhesion. [3]
However, rolling/static friction does not create heat, since it prevents motion. "Rolling friction depends on the coefficient of rolling friction between the two materials (µr) and the normal force (N) of the object. The force of kinetic friction depends on the coefficient of kinetic friction between the object and the surface on which it is ...
Similar to rolling friction there are energy terms in charge transfer, which contribute to friction. In static friction there is coupling between elastic strains, polarization and surface charge which contributes to the frictional force. [82] In sliding friction, [108] when asperities contact [38] and there is charge transfer, some of the ...
Hertz solved the contact problem in the absence of friction, for a simple geometry (curved surfaces with constant radii of curvature). Carter considered the rolling contact between a cylinder and a plane, as described above. A complete analytical solution is provided for the tangential traction.
Traction can also refer to the maximum tractive force between a body and a surface, as limited by available friction; when this is the case, traction is often expressed as the ratio of the maximum tractive force to the normal force and is termed the coefficient of traction (similar to coefficient of friction).