Nonlinear Vibration Isolator with Softening Spring and Nonlinear Damping

Abstract

In recent decades, nonlinear isolators have become widely used to solve problems of passive isolation of unwanted vibrations. A special place is occupied by nonlinear stiffness isolation supports, which provide high static stiffness along with low dynamic stiffness or even quasi-zero stiffness (QZS) in the displacement range. These vibration isolators provide a higher isolation bandwidth with low transfer capacity than conventional linear devices. In this paper, nonlinear single-degree of freedom (DOF) vibration isolator with quadratic and cubic nonlinear stiffness components and a quadratic damping component is analyzed. The system responses and magnitude of force transmissibility in the vicinity of resonant frequency are analyzed. The dynamic response is obtained using the harmonic balance method. A significant contribution from the quadratic component of the damping force is emphasized. Also asymptotical formulas for responses magnitude, resonant frequency and force transmissibility there are presented, which allow optimizing the choice of the parameters of the isolator more easily.