Stick slip (or "slip stick") is called the phenomenon that sometimes, during the sliding of two bodies over each other, spontaniously a jerking movement appears. This jerking movement is often attended by a yelling noise.

Cause

The cause of the phenomenon is the friction between two jerking bodies. The force to overcome the static friction, is larger than the force that is needed to overcome the dynamic friction. In other words, the static friction coëfficient is larger than the dynamic friction coëfficient.

Attached picture shows symbolically what happens.

V is the drive system, R is the elasticity in the system and M is the load that is laying on the floor and must be moved.. When the drive system is started, the Spring R is loaded and the pushing force against load M is increasing until the static friction coefficient between load M and the floor is not able to hold the load anymore. The load starts sliding and the friction coefficient decreases from its static value to its dynamic value. At this moment in fact the spring can give more power and accelerates mass M. During M’s movement, the force of the spring decreases, until it is insufficiant to overcome the dynamic friction. Now the Mass M stops. The drive system however continues and the spring is loaded again etc. Image File history File links Stick-slip. ...

Examples

Examples of stick slip can be heard from hydraulic cylinders, honing machines etc. Special dopes can be added to overcome the stick slip effect. Also the music that comes from a violin is the result of the stick slip phenomenonbut also the noise of carbrakes and the noise of a stopping train.