A SIMPLE MODEL FOR INVESTIGATING THE NON-LINEAR DYNAMIC BEHAVIOR OF ELASTIC SYSTEMS SUBJECTED TO STICK-SLIP MOTION

The stick-slip phenomenon is the typical jerking motion that may occur when two objects are forced to slide with friction over each other. There are several situations in which this motion can be observed in practice, for example, between the components of different kinds of seis- mic protection systems, like the slabs of some friction dampers or the sliding elements of some base isolation systems. These kinds of systems are generally designed to work in a smooth, flawless manner. However, it cannot be excluded that in particular situations undesired jerk- ing motions might develop. Similar situations are widespread in all areas of engineering and may result in complex dynamic behavior, even when only a small number of degrees of free- dom are involved. A well-known simple scheme for problems of this kind consists of a rigid block connected elastically to one support while its base is in contact with a second, moving rough surface. This model, despite its apparent simplicity, can provide useful indications on the main features of many physical systems. This contribution illustrates an analytical study conducted to better understand the non-linear dynamic behavior of such systems, with the ob- jective of identifying conditions that may disrupt their proper functioning. In particular, the equations of motion are solved analytically, the sticking and sliding phases are studied, the influence on the solution of the system’s main parameters is investigated, and some typical long-term system responses are discussed. Lastly, some results obtained by means of a specif- ically developed numerical procedure are illustrated