Dynamical Friction Phenomena and Friction‐Induced Vibrations in Pneumatic Sealings

Abstract

Especially from dry sliding contacts between solids the description of the friction by the law of Coulomb is well-known. This law describes the relation between normal force and tangential force via the proportional factor µ, the coefficient of friction. This coefficient has to be derived empirically by experiments and is considered as being dependent only on the solid bodies' materials and surfaces. On the contrary seals are usually lubricated contacts. A viscoelastic seal material interacts with a hard solid counterpart in the state of mixed friction, i.e. viscous friction, hysteresis friction, and adhesion take effect simultaneously. The result is a friction characteristic which shows strong dependence on the sliding velocity, described e.g. by Richard Stribeck with the 'Stribeck-curve', which was initially describing the friction of a journal bearing. One particularity of this curve is a decreasing coefficient of friction for increasing sliding velocity in the range of small velocities. It can be shown, that this decrease can cause friction induced vibrations and other undesired dynamical effects for certain mechanical properties of a system with sliding contact. In this contribution the identification of friction induced dynamics and the development of a minimal model is carried out at the example of pneumatic sealing contacts in an industrial application. Furthermore model-based measures are shown that prevent the application from performing undesired dynamical effects. The results are validated experimentally.