Behavior of iron-based Shape Memory Alloys under Cyclic Loading Histories

Shape memory alloys (SMAs) have gained considerable attention in a broad range of engineering applications. In particular, iron-based SMAs (Fe-SMAs) have been recently developed and used as a cost-effect method for prestressed-strengthening of civil structures. Previous studies have shown that Fe-SMA offers a strong shape memory effect (SME), however, a negligible superelastic behavior. The potential use of Fe-SMAs in seismic design and retrofit applications including supplemental damping is not yet clear and requires the further understanding of the material behavior under large amplitude cyclic inelastic straining. This study discusses key findings from a material-level experimental program that involved Fe-SMA round coupons subjected to a broad range of uniaxial cyclic strain histories representative of earthquake loading. The Fe-SMA material properties associated with its nonlinear behavior, including cyclic hardening are discussed.