An Air Spring Vibration Isolator Based on a Negative-Stiffness Structure for Vehicle Seat

Abstract

This research introduces an air spring vibration isolator system (ASVIS) based on a negative-stiffness structure (NSS) to improve the vehicle seat’s vibration isolation performance at low excitation frequencies. The main feature of the ASVIS consists of two symmetric bellows-type air springs which were designed on the basis of a negative stiffness mechanism. In addition, a crisscross structure with two straight bars was also used as the supporting legs to provide the nonlinear characteristics with NSS. Moreover, instead of using a vertical mechanical spring, a sleeve-type air spring was employed to provide positive stiffness. As a result, as the weight of the driver varies, the dynamic stiffness of the ASVIS can be easily adjusted and controlled. Next, the effects of the dimension parameters on the nonlinear force and nonlinear stiffness of ASVIS were analyzed. A design process for the ASVIS is provided based on the analytical results in order to achieve high static–low dynamic stiffness. Finally, numerical simulations were performed to evaluate the effectiveness of the ASVIS. The results obtained in this paper show that the values of the seat displacement of the ASVIS with NSS were reduced by 77.16% in comparison with those obtained with the traditional air spring isolator without NSS, which indicates that the design of the ASVIS isolator with NSS allows the effective isolation of vibrations in the low-frequency region.

Dynamic Analysis of Quasi-Zero Stiffness Pneumatic Vibration Isolator

“…A quasi-zero stiffness isolator based on a set of two double-acting pneumatic linear actuators is analyzed and demonstrated experimentally by Palomares et al [29], obtaining a reduction in resonance frequency. Nguyen et al [30] analyzed an air spring vibration isolation system based on a negative stiffness structure, showing that the load capacity of the isolator can be adjusted easily via the gas pressure. Motivated by the interest of the scientific community toward quasizero stiffness vibration systems and promising application, authors developed and realized the static analysis of a quasi-zero stiffness pneumatic vibration isolator (QZSPVI) [31] in which a pneumatic cylinder with an auxiliary tank worked as an elastic element, revealing that the stiffness curve of the isolator is asymmetrical around the desirable equilibrium position.…”