A Reconfigurable High-Static-Low-Dynamic-Stiffness Vibration Isolator Applicable for Different Payload Masses

Nonlinear vibration isolators with high-static-low-dynamic-stiffness (HSLDS) can achieve low-frequency isolations, while they are usually applicable to a limited range of payload mass. To address the issue, a reconfigurable HSLDS isolator is proposed based on compliant structures. The isolator can be assembled as a unilateral configuration and a bridge-type configuration, exhibiting low-frequency isolations for both light and heavy payloads in the experiments. To reveal the mass adaption mechanism of the proposed isolator, a theoretical analysis is performed. The restoring force of the compliant structure is characterized by a beam constraint model and validated by a finite element analysis and experiments. The reconfiguration of the isolator changes the geometric constraint of the structure during deformations. The unilateral structure exhibits weakly softening stiffness in the experimental range. The bridge-type configuration demonstrates strongly softening and negative stiffness, presenting obvious HSLDS at large deformation. The vibration equation of the isolator is established based on the restoring forces of both configurations and the frequency responses are obtained through a harmonic balance method. The frequency responses under different masses, different excitations and different damping ratios are investigated. A further discussion on the mass adaption range is provided. This work provides a new insight into realizing HSLDS isolators applicable to a wide range of payload mass by the reconfiguration of basic compliant structures.