Design of a Quasi-Zero Stiffness Vibration Isolator Based on Cosine Curved Beams

Abstract

To improve low-frequency vibration isolation while maintaining load-bearing stability, this paper proposes a quasi-zero-stiffness (QZS) vibration isolator based on cosine-curved flexible beams. The isolator consists of a rigid frame and two mutually perpendicular curved beams, whose geometric nonlinearity is used to realize the QZS characteristic. A static model considering frame constraints and fixed-end effects is established to derive the force–displacement relationship and analyze the influence of key structural parameters. A single-degree-of-freedom nonlinear dynamic model is then developed to evaluate the transmissibility of the system and compare it with an equivalent linear isolator. The results show that the proposed structure can achieve QZS behavior through appropriate parameter matching and exhibits a lower and left-shifted resonance peak, indicating improved low-frequency isolation performance. This study provides design guidance for compact compliant vibration isolators with ultra-low-frequency isolation capability.