Novel Self-Centering Negative Stiffness Damper Based on Combination of Shape Memory Alloy and Prepressed Springs

Abstract

This paper proposes a novel self-centering negative stiffness damper (SCNSD), which combines superelastic shape memory alloy (SMA) and prepressed springs in parallel for damping enhancement. A mechanical model of the damping force is established and experimental tests are conducted for verification. The influence of the negative stiffness provided by the prepressed springs is investigated by parametric analysis. A single-degree-of-freedom (SDOF) structure is used as a case to study the damping effectiveness of the proposed damper. The low limit of the negative stiffness is established, and the additional equivalent damping ratio is deduced theoretically. Frequency response under harmonic excitation is evaluated by using the average method. Numerical simulation is carried out to explore the damping effectiveness of the SCNSD for suppressing the seismic response of the SDOF structure. These numerical simulation results show that the SCNSD can achieve a larger damping ratio due to the effect of the negative stiffness, and the acceleration and displacement response of the SDOF system can be reduced remarkably.