Cornering force or side force is the lateral (i.e., parallel to wheel axis)
force
In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a ...
produced by a vehicle
tire during cornering.
Cornering force is generated by tire
slip and is proportional to
slip angle at low slip angles. The rate at which cornering force builds up is described by
relaxation length
Relaxation length is a property of pneumatic tires that describes the delay between when a slip angle is introduced and when the cornering force reaches its steady-state value.
It is also described as the distance that a tire rolls before the later ...
. Slip angle describes the deformation of the tire
contact patch, and this
deflection
Deflection or deflexion may refer to:
Board games
* Deflection (chess), a tactic that forces an opposing chess piece to leave a square
* Khet (game), formerly ''Deflexion'', an Egyptian-themed chess-like game using lasers
Mechanics
* Deflection ...
of the contact patch deforms the tire in a fashion akin to a
spring
Spring(s) may refer to:
Common uses
* Spring (season), a season of the year
* Spring (device), a mechanical device that stores energy
* Spring (hydrology), a natural source of water
* Spring (mathematics), a geometric surface in the shape of a h ...
.
As with
deformation of a spring, deformation of the tire contact patch generates a
reaction force in the tire; the cornering force.
Integrating the force generated by every tread element along the contact patch length gives the total cornering force. Although the term, "tread element" is used, the compliance in the tire that leads to this effect is actually a combination of sidewall deflection and deflection of the
rubber
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and ...
within the contact patch. The exact ratio of sidewall compliance to tread compliance is a factor in tire construction and inflation pressure.
Because the tire deformation tends to reach a maximum behind the center of the contact patch, by a distance known as
pneumatic trail, it tends to generate a torque about a vertical axis known as
self aligning torque.
The diagram is misleading because the reaction force would appear to be acting in the wrong direction. It is simply a matter of
convention to quote positive cornering force as acting in the opposite direction to positive tire slip so that calculations are simplified, since a vehicle cornering under the influence of a cornering force to the left will generate a tire slip to the right.
The same principles can be applied to a tire being deformed longitudinally, or in a combination of both longitudinal and lateral directions. The behaviour of a tire under combined longitudinal and lateral deformation can be described by a
traction circle
Traction may refer to:
Engineering
*Forces:
** Traction (engineering), adhesive friction or force
** Traction vector, in mechanics, the force per unit area on a surface, including normal and shear components
* Traction motor, an electric motor ...
.
See also
*
Camber thrust
*
Lateral force variation
*
Circle of forces
*
Skidpad
References
{{DEFAULTSORT:Cornering Force
Tires
Automotive steering technologies
Force
Motorcycle dynamics