12. Frictional Damping

Friction is a dissipative process, in which mechanical energy is transformed into heat. This can be both unwanted as well as purposefully taken advantage of. Even at very small amplitudes of tangential oscillations, the small slip displacements at the border of the contact area always lead to energy dissipation. This effect is the physical mechanism of damping in periodically forced frictionally engaged joints, for example, in leaf springs for commercial and transportation vehicles. Similar effects are generally exhibited in all frictionally engaged joints and are, therefore, of great interest. For the investigation of damping caused by dry friction, a dynamic tangential contact is of interest. The exact coincidence of the frictional damping in a true three-dimensional contact and its one-dimensional representation in the framework of the method of dimensionality reduction follows from general theorems concerning tangential contacts. This chapter is an illustration of how the use of the MDR makes dynamic tangential problems simple without loss of exactness.