Bistability-enabled quasi-zero stiffness for low-frequency vibration isolation

Low frequency vibrations (5–25 Hz) dominate the energy content of electromechanical equipment and are a primary cause of performance degradation and failure. Conventional linear isolators face an inherent trade off between achieving a low isolation onset frequency and maintaining high static load capacity. To address this limitation, a quasi-zero-stiffness (QZS) isolator based on an Euler curved beam configuration is developed. The main contributions are threefold. First, a quantitative mapping relationship between the unit cell geometric parameter and the array level restoring force is established, enabling direct translation of load requirements into mold design dimensions. Second, the nonlinear dynamic response is analysed using the harmonic balance method to quantify amplitude frequency characteristics, stability boundaries, transmissibility, and jump phenomena, with parametric boundaries identified to guide the selection of damping and nonlinear stiffness. Third, a practical four step design methodology is synthesized to translate specific engineering targets static load and isolation onset frequency directly into physical dimensions and array configurations. Finite element simulations and experimental tests on a molded polyurethane prototype are conducted for validation. The isolator achieves an isolation onset frequency of 9.375 Hz in experiments (8.7 Hz in simulation) while supporting a static load of approximately 320 N. The proposed design provides a compact and reliable solution tailored for the specific spatial and load constraints of electromechanical systems.