Abstract
The negative stiffness exhibited by bi-stable mechanisms together with the tunable superelasticity offered by shape memory alloy (SMA) wires can enhance the dynamic resilience of a structure in the context of vibration isolation. The effects of negative stiffness and superelastic damping in base-isolated structures are here explored by carrying out an extensive study of the nonlinear dynamic response via pathfollowing, bifurcation analysis, and time integration. The frequency-response curves of the isolated structure, with and without the negative stiffness contribution, are numerically obtained for different excitation amplitudes to construct the acceleration and displacement transmissibility curves. The advantages of negative stiffness, such as damping augmentation and reduced acceleration/displacement transmissibility, as well as the existence of rich bifurcation scenarios toward quasi-periodicity and chaos, are discussed.
Highlights
Passive vibration isolation is one of the most popular and effective vibration control techniques
The dynamic response provided by a SDOF system, representing the isolated structure controlled by a negative stiffness-shape memory alloy (SMA) (NS-SMA) damping mechanism, is investigated by employing suitable hysteretic constitutive laws modeling the nonlinear response of the bearing devices and the superelastic response of the SMA element
The total restoring force f of the proposed isolation system is the summation of the force fi provided by traditional seismic elastomeric isolators, the superelastic force fs and the force fn provided by the negative stiffness mechanism
Summary
Passive vibration isolation is one of the most popular and effective vibration control techniques. Donmez et al [33] studied the dynamic response of a dry-friction QZS isolator, showing that the hysteretic damping ensures a better performance than viscous damping in the out-of-resonance frequency range In all of these works, negative stiffness correction is used to achieve zero stiffness in the equilibrium position, but as known, in typical civil applications dealing with seismic horizontal isolation, this is undesirable because of the need of a wind restraint. The dynamic response provided by a SDOF system, representing the isolated structure controlled by a negative stiffness-SMA (NS-SMA) damping mechanism, is investigated by employing suitable hysteretic constitutive laws modeling the nonlinear response of the bearing devices and the superelastic response of the SMA element
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