Damping and frequency of a model cable attached with a pre-tensioned shape memory alloy wire: Experiment and analysis

This study proposed a system consisting of a stay cable transversely attached with a pre-tensioned shape memory alloy (SMA) wire. Cyclic tension loading test of pre-tensioned 0.5-mm-diameter NiTi wire was conducted first. The effective modulus and energy dissipation per unit volume were obtained from the tested hysteretic loops of the pre-tensioned SMA wire. The effects of prestrain on the energy dissipation and effective modulus of the SMA wire was discussed. Preliminary fatigue testing of 0.5-mm- and 1.0-mm-diameter SMA wires was carried out, and a vibration mitigation experiment with a model stay cable transversely attached with a pre-tensioned SMA wire was then conducted. Both the first and the second in-plane mode vibrations were tested. The effects of the SMA wire installation location and pre-tension level on the frequency and damping ratio of the model-cable-SMA-wire system were discussed. The test results confirmed there was an optimal pre-tension level of the SMA wire for maximum mode damping, and in this test, the maximum damping ratio was larger than 0.50%. A preliminary linearized theoretical study was also carried out to further explore the dynamics of the model-cable-SMA-wire system. The comparison results showed good agreement of theoretical frequency and damping to the tested version. The study confirmed the potential application of pre-tensioned SMA wires as cross-ties for stay cable vibration mitigation.