Vibration Isolation Performance Study of Shape Memory Alloy-Triple Spring Quasi-Zero-Stiffness System under Base Excitation

In many critical scientific and engineering fields, controlling low-frequency vibrations is essential. The existing triple spring quasi-zero stiffness (QZS) isolator shows effective performance in low-frequency vibration control; however, its limited QZS range leads to reduced isolation bandwidth and deteriorated performance when structural displacement responses are large. To address this issue, this study proposes an improved QZS isolation system by partially replacing the vertical positive stiffness spring with a shape memory alloy (SMA) spring. The secondary stiffness characteristics and pseudoelasticity of the SMA spring are utilized to expand the QZS working range. The dynamic equations of the modified system, which exhibit piecewise nonlinear characteristics, are solved using the averaging method and validated numerically. The influence of various SMA parameters on the dynamic response of the improved system is analyzed. The results demonstrate that the SMA-enhanced triple spring QZS isolator exhibits a broader QZS range and superior low-frequency vibration isolation performance compared to the traditional triple spring QZS isolator.