The nonlinear dynamic behavior of a Rubber-Layer Roller Bearing (RLRB) for vibration isolation

In this paper, we study the dynamic behavior of a Rubber-Layer Roller Bearing (RLRB) interposed between a spring-mass elemental superstructure and a vibrating base. Thanks to the viscoelastic rolling contact between the rigid rollers and the rubber layers, the RLRB is able to provide a nonlinear damping behavior. The effect of the RLRB geometric and material parameters is investigated under periodic base excitation, showing that both periodic and aperiodic responses can be achieved. Specifically, since the viscoelastic damping is non-monotonic (bell shaped), there exist system dynamic conditions involving the decreasing portion of the damping curve in which a strongly nonlinear behavior is experienced. In the second part of the paper, we investigate the effectiveness of the nonlinear device in terms of seismic isolation. Focusing on the mean shock of the Central Italy 2016 earthquake, we opportunely tune the material and geometrical RLRB parameters, showing that a significant reduction of both the peak and root-mean-square value of the inertial force acting on the superstructure is achieved, compared to the best performance of a linear base isolation system.