Experimental and Numerical Studies on Fe–Mn–Si Alloy Dampers for Enhanced Low-Cycle Fatigue Resistance

AbstractA new type of Fe–Mn–Si alloy damper is developed in this study to enable significant enhancement of the low-cycle fatigue (LCF) resistance compared with conventional metal dampers. A set of material tests was conducted first to foster a good understanding of the basic mechanical properties of the Fe–Mn–Si alloy, followed by a comprehensive experimental study on 18 shear damper specimens, considering different materials, connection types, restraining conditions, and loading protocols. A numerical investigation was also conducted to help interpret the test results. Among other important findings, the study reveals that the Fe–Mn–Si alloy exhibits a non-obvious yield plateau followed by noticeable strain hardening under monotonic loading. The fracture strain attains 57.4%, showing good ductility. Under cyclic loading, the Fe–Mn–Si alloy dampers exhibit different failure modes compared with their normal steel counterparts. The former mainly fails in fracture near the center of the plate, whereas the fracture of the latter tends to initiate from the edge. Importantly, the Fe–Mn–Si alloy dampers show fatigue life and total energy dissipation capacity up to 10 times that of their steel counterparts. Using buckling-restraining plates brings further benefits to the fatigue resistance and energy dissipation capacity. A combined kinematic/isotropic hardening model is shown to adequately capture the hysteretic behavior of the Fe–Mn–Si alloy material, where calibrated parameters are given. Finally, building on the findings from the present study, future research opportunities regarding the analysis and design of Fe–Mn–Si components, including their weld and heat affected zones, are highlighted.