Bio-inspired tensegrity isolator for tunable quasi-zero-stiffness and low-frequency vibration isolation

Vibration-induced fatigue and performance degradation remain pervasive challenges across engineering systems. Developing high-performance isolators is therefore essential for ensuring stability and precision. Quasi-zero-stiffness (QZS) mechanisms offer an effective means to reconcile the inherent tradeoff between high load-bearing capacity and low-frequency vibration isolation. However, conventional QZS designs often suffer from narrow operational regions, complex structures, and limited tunability. Inspired by the biomechanics of insect jumping legs, this study proposes a tensegrity-based quasi-zero-stiffness (TQZS) isolator that integrates positive-stiffness springs with a bio-inspired negative-stiffness module. A comprehensive parametric analysis uncovers the multi-parameter coupling laws governing the structural response, thereby providing extensive design freedom for tailoring QZS characteristics. The isolation bandwidth and load-bearing capacity can be tuned by adjusting the prestress level, stiffness ratio, and damping coefficient. Our experiments further confirm the theoretical predictions, showing near-zero stiffness around the equilibrium position in static tests and an isolation onset frequency as low as 1 Hz under dynamic excitation. Compared with conventional QZS isolators, the proposed TQZS exhibits a much wider QZS interval and enhanced robustness under large-amplitude excitations. This work introduces an insect-inspired compact, tunable, and high-performance isolator concept for next-generation low-frequency vibration isolation applications.