Displacement and Force Transmissibility of a High-Static-Low-Dynamic-Stiffness Isolator with Geometric Nonlinear Damping

In this paper, a high-static-low-dynamic-stiffness (HSLDS) isolator with geometric nonlinear damping is proposed in order to improve the performance of low-frequency vibration isolation. The geometric nonlinear damping characteristic of the HSLDS system is analyzed.

The Lagrange principle is employed to establish the differential equation of motion of a vibration system with the proposed isolator. The harmonic balance method (HBM) is then applied to derive the steady-state responses under base and force excitations, respectively. The vibration isolation performance of the proposed system is thus analyzed and discussed for different parameters.

The results show that increasing nonlinear damping can significantly reduce the displacement transmissibility peak in the resonant zone without apparently influencing the performance at higher frequencies. Similarly, when subjected to force excitation, an increase in nonlinear damping notably reduces the force transmissibility peak in the resonant region while the vibration isolation performance at higher frequencies remains unaffected. It is also determined that increasing the stiffness ratio can effectively suppress the displacement and force transmissibility, and extend the isolation region.

It is found that the integration of geometric nonlinear damping into the HSLDS isolator effectively enhances system performance and is suitable for low-frequency vibration isolation.