Vibration Isolation Performance of Composite High-Order Quasi-Zero Stiffness Vibration Isolator

This paper proposes a novel composite high-order quasi-zero stiffness (HO-QZS) vibration isolator that achieves HO-QZS characteristics through the integration of a positive stiffness spring, a negative stiffness cam-roller-horizontal spring (CRHS) mechanism, and a magnetic levitation module. In system modeling, nonlinear restoring force equations were derived for both the CRHS mechanism and magnetic levitation structure. Utilizing parametric design theory for QZS systems, a dimensionless dynamic control equation containing only a seventh-order stiffness term with parameter g was developed through Taylor expansion and dimensional normalization methods. The steady-state response, stability, and vibration transmission characteristics were analyzed using the harmonic balance method and numerical integration verification. Research results demonstrate that HO-QZS designs (e.g. fifth-order QZS) significantly reduce the initial isolation frequency (36.78% lower than non-QZS systems) by expanding the quasi-zero stiffness region, while suppressing peak transmissibility (3.81[Formula: see text]dB attenuation compared with non-QZS systems). Parametric sensitivity analysis reveals that increased damping ratio effectively suppresses resonance peaks but compromises high-frequency isolation performance. Larger excitation amplitudes induce stiffness hardening effects, and reduced stiffness coefficients improve isolation efficiency while introducing dynamic stability challenges in low-frequency ranges. This study provides theoretical and design foundations for low-frequency vibration isolation engineering.