Dynamic modeling and characteristic analysis of an adjustable four-spring parallel quasi-zero-stiffness isolator for different loads

Abstract

Aiming at address the issue that the vibration isolation performance of existing quasi-zero-stiffness isolation seats will be weakened under varying load conditions, an adjustable four-spring parallel quasi-zero-stiffness isolator (FPQZSI) is proposed. On the basis of the traditional three-spring quasi-zero-stiffness structure, the physical model of the designed FPQZSI is determined by introducing the tilt linkage. Then, the dynamic model of the FPQZSI is established based on the Lagrange’s principle, and the support force expression of the FPQZSI is determined. By analyzing the output stiffness characteristics of the FPQZSI, the structural parameter relationships that confer quasi-zero-stiffness characteristics at the equilibrium position are determined. Additionally, the influence of the tilt linkage angle on the system’s load-bearing capacity is analyzed. Furthermore, the steady-state response of the designed FPQZSI under harmonic force excitation is solved by using the harmonic balance method. The influences of the parameters, such as the tilt linkage angle, on the amplitude-frequency response characteristics and force transmission characteristics of the FPQZSI are also examined. Finally, the vibration isolation performance of the designed FPQZSI is verified through numerical calculation analysis and prototype experimental testing.