Vibration Isolation Characteristics and Chaos of Double-Layer Nonlinear Air Spring System

Air springs exhibit strong nonlinear characteristics and outstanding vibration isolation performance, and can be adjusted to different mass loads by varying the air pressure. This paper introduces an air spring vibration isolation device with nonlinear characteristics, integrated into the traditional linear vibration isolation system, to create a double-layer nonlinear vibration isolation system. This study establishes the mathematical relationship between the air spring load and compression displacement through a combination of theoretical derivation and finite element simulation. Furthermore, a dynamic model of the double-layer nonlinear vibration isolator with an air spring is developed. The averaging method is used to derive the amplitude–frequency response equation of the forced vibration of the system under harmonic excitation. The present study analyses the effects of various parameters on the amplitude–frequency behavior and vibration transmissibility of the system. The vibration isolation characteristics are compared with those of double-layer linear and single-degree-of-freedom isolators. Finally, the influence of the amplitude of the excitation force and frequency ratio on the system is used as an example to analyze the bifurcation characteristics of the system and to study the nonlinear dynamics of the system. The results show that the double-layer nonlinear vibration isolation system, comprising an air spring, exhibits excellent vibration isolation capabilities. By selecting an appropriate damping ratio, nonlinear and linear stiffness ratio, and mass ratio, the initial vibration isolation frequency of the double-layer nonlinear vibration isolation system can be diminished, the attenuation rate of the system transmissibility in a specific frequency band can be accelerated, and the vibration isolation performance of the system can be enhanced.