Influence of the thermomechanical behavior of NiTi wires embedded in a damper on its damping capacity: Application to a bridge cable

Thanks to high dissipation properties, embedding NiTi Shape Memory Alloys in passive damping devices is effective to mitigate vibrations in building and cable structures. These devices can inconceivably be tested directly on full-scale experimental structures or on structures in service. To predict their effectiveness and optimize the set-up parameters, numerical tools are more and more developed. Most of them consist of Finite Element models representing the structure equipped with the damping device, embedding parts associated with a superelastic behavior. Generally, the implemented behavior laws do not include all the phenomena at the origin of strain energy dissipation, but stress-induced martensitic transformation only. This article presents a thermomechanical behavior law including the following phenomena: (i) intermediate R-phase transformation, (ii) thermal effects and (iii) strain localization. This law was implemented in a commercial Finite Element code to study the dynamic response of a bridge cable equipped with a NiTi wire-based damping device. The numerical results were compared to full-scale experimental ones, by considering the above-mentioned phenomena taken coupled or isolated: it has been shown that it is necessary to take all of these phenomena into account in order to successfully predict the damping capacity of the device.