Semi-active vibration control device based on superelastic NiTi wires

摘要

The present paper presents a physical prototype that simulates the response of a single degree of freedom dynamicnsystem, equipped with a novel semi-active vibration control device. This device comprises two superelastic NiTinelements working in phase opposition and aims to prevent deck unseating in simply supported bridges, during anseismic excitation. The special design of this device allows to avoid problems related to stress–relaxation phenomenanand material degradation because of cyclic loading that have been observed in similar passive dissipation devices. Thenproposed design uses a strategy that permits the continuous adapting of the accumulated stress in the NiTi wires, on thenbasis of the response of the device to external excitations. Although unloaded, the NiTi elements remain strain/stressnfree, preventing stress–relaxation phenomena. With the occurrence of a dynamic excitation, a cumulative strain/stressnprocess in the superelastic wires is initiated, enabling higher martensite transformation ratios and therefore increasingnthe damping capacities of the system while keeping the stresses in the wires inside a narrower superelastic window.nThe strain/stress accumulation in the superelastic wires is a direct result of the motion of the structure itself, with nonneed for external energy input. Copyright © 2012 John Wiley & Sons, Ltd.