Nonlinear viscoelastic isolation for seismic vibration mitigation

Controlling structural vibration is a long-standing problem and a key design requirement in several applications, as witnessed by the huge effort made in the last decades in developing innovative devices, and associated modelling methodology, specifically suited for this purpose. Moreover, the range of engineering branches facing this problem is definitely wide as all systems involving moving parts lead to vibrations. It is, for instance, the case of wind turbine whose vibration generates both from internal (e.g. rotordynamics balancing, The aim of this paper is to assess the effectiveness of nonlinear viscoelastic damping in controlling base-excited vibrations. Specifically, the focus is to investigate the robustness of the nonlinear base isolation performance in controlling the system response due to a wide set of possible excitation spectra. The dynamic model is derived to study a simple structure whose base isolation is provided via a Rubber-Layer Roller Bearing (RLRB) (rigid cylinders rolling on rigid plates with highly damping rubber coatings) equipped with a nonlinear cubic spring, thus presenting both nonlinear damping and stiffness. We found that, under periodic loading, due to the non-monotonic bell-shaped viscoelastic damping arising from the viscoelastic rolling contacts, different dynamic regimes occur mostly depending on whether the damping peak is overcome or not. Interestingly, in the former case, poorly damped self-excited vibrations may be triggered by the steep damping decrease. Moreover, in order to investigate the robustness of the isolation performance, we con-sider a set of real seismic excitations, showing that tuned nonlinear RLRB provide loads iso-lation in a wider range of excitation spectra, compared to generic linear isolators. This is peculiarly suited for applications (such as seismic and failure engineering) in which the specific excitation spectrum is unknown a priori, and blind design on statistical data has to be employed. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The paper evaluates the effectiveness of nonlinear viscoelastic damping in controlling base-excited vibrations. It investigates the robustness of nonlinear base isolation performance in controlling system response to a wide set of possible excitation spectra, showing that tuned nonlinear RLRB provides loads isolation in a wider range of excitation spectra.