Angular friction

Friction is a force that acts to stop relative motion. According to the laws of friction, angular friction always acts opposite to motion and parallel to the surface of contact. But, the complexity in calculation arises when the relative motion between the objects is not linear. For example in the case of a turning car, the motion is curvilinear. In such cases, the term angular friction might be used. In this article, we try to define angular friction with examples and recent research studies.

The direction of friction in a linear relative motion

friction in a linear relative motion.
Direction of friction in a linear relative motion

In the case of a linear motion, there is no angular component involved. The equation is strait-forward f = μN. There is no angular friction involved here, it’s all linear.

Curvilinear motion

angular friciton in a curvilinear motion
Friction during curvilinear motion. Image by Oleksandr Pyrohov from Pixabay 

In a curvilinear motion, there is a continuous change in direction. It is complex to define friction in such scenarios. There is a combination of friction and friction torque. You can read this article titled “friction forces at the wheel’s contact with the ground in a turning vehicle” to understand how the contact between the wheel and the ground is defined during curvilinear motion.

Frictional torque

Frictional torque occurs when there is a rotational relative motion. For example, the door turning on its hinges and a cyclist doing a wheelie on the front wheel. You can read this article “Numerical and Experimental Studies of the Attenuation Characteristics of Friction Torque in a Wet Multidisc Clutch” to understand the frictional torque in the working of a clutch.

This article titled “Enhancement of Tribological Behavior of Rolling Bearings by Applying a Multilayer ZrN/ZrCN Coating” explains the testing protocols for friction torque.

You can read about different friction torque calculation models in this article titled “Friction torque of wind-turbine pitch bearings – comparison of experimental results with available models“. The authors have calculated the frictional torque of pitch bearings in wind turbines under load.

The angle of friction and angular friction

comparison between angel of friction and angular friction
Angle of friction

The angle of friction is different from angular friction. The angle of friction can be defined as the minimum angle of inclination at which an object begins to slide. This is generally used to represent the static friction of the surface. The tangent of the angle will be equal to the coefficient of limiting static friction. But angular friction is a term that Implies that the friction acting on the object is at an angle and not linear.

See Also