Analysis of a bio-inspired vibration isolator with a compliant limb-like structure

Abstract

Bio-inspired isolators are a novel type of nonlinear isolators by mimicking the bionic structures and behaviors. Most of them are based on limb-like structures composed of rigid rods forming a geometric frame and linear springs storing elastic energy. A novel bio-inspired isolator with a compliant limb-like structure was proposed. Both the geometric constrained movement and the storage of the elastic energy are provided by the deformation of a compliant mechanism. A beam constraint model was adopted to characterize the nonlinear restoring force, and a harmonic balance method was used for the dynamic analysis. The minimum damping ratio ensuring the isolator operating within a working region was estimated, and the displacement transmissibility of the isolator was calculated. A systematic investigation was performed on the high-static-low-dynamic-stiffness characteristic and the vibration isolation performance of the proposed isolator. The investigation revealed that the compliant limb-like structure exhibits stiffness-softening, stiffness-softening-hardening, and negative-stiffness characteristics with different dimensions and deformation degrees. The dimensions can be optimized to achieve the largest high-static-low-dynamic-stiffness region, and the smallest dynamic/static stiffness ratio. The isolator exhibits a globally stable response and a weak nonlinearity if it is fully damped, while jump phenomena and unbounded response may occur with light damping. Compared with a three-spring isolator and a rigid limb-like structure, the compliant limb-like structure exhibits a strong stability, a strong load capacity, and a noticeable high-static-low-dynamic-stiffness characteristic at the same time. The combination of the bio-inspired isolation and the compliant mechanism may provide an innovative approach for the broadband vibration isolation.