Quasi-Zero-Stiffness Design for 6-DoF Vibration Isolation of High-Mass Systems Across Broad Frequency Ranges

This paper presents a design methodology for a multi-directional quasi-zero-stiffness (QZS) system that can achieve vibration isolation of large bodies with high masses across a broad frequency range in all six degrees of freedom in space. The system is based on a QZS design combined with an elastic bedding approach utilizing helical compression springs. Unlike many existing QZS approaches, the proposed system satisfies practical application constraints as well as requirements common in ultra-precision manufacturing. Specifically, it eliminates conventional mechanical joints to prevent particle abrasion and avoids critical high natural frequencies within the isolation system itself. In a two-stage design process, the system is first designed for vibration isolation in all three translational directions and then extended to all six directions through the spatial arrangement of the springs. By analytically deriving and evaluating the system’s stiffness matrix, the mutual dependencies between the positions of the springs and the resulting natural behavior are investigated to determine a suitable system configuration. The findings demonstrate the feasibility of designing a QZS system capable of stable vibration isolation for a body with a mass of 2500 kg that can be tuned to achieve target natural frequencies of about 2 Hz in all six degrees of freedom, while providing internal natural frequencies of the isolation system above a target value of 1000 Hz. In comparison to a conventional vibration isolation system, reductions in the natural frequency of up to 80% were achieved.