Modelling of friction phenomena in sliding conditions in suspension shock absorbers

Friction phenomena are extremely important in the suspension mechanisms used in automotive vehicles. Currently, there is no theory capable of explaining all the friction phenomena from a global perspective. In the case of telescopic hydraulic shock absorbers, the additional contribution of force given by the friction in the range of low damping velocities increases the capability of energy dissipation. In contrast, the continuous transitions between adherence and sliding of the telescopic mechanism diminishes the capability of generating comfort. Moreover, the fluctuations of inner pressures and external side loads have to be added as purely dynamic factors affecting the friction variations. This paper explains the improvements obtained in the modelling of friction phenomena in sliding conditions, by proposing a new formulation of the Stribeck effect and the viscous friction, considering these two effects as associated concepts in the case of the suspension shock absorbers.