A combined analytical model for orifice-type and pipe-type air springs with auxiliary chambers in dynamic characteristic prediction

Abstract

The frequency-domain properties of air springs with an auxiliary chamber are highly dependent on the type of air flow passages. The dynamic characteristics of air springs with different flow passages are so variated that they are modeled separately. This paper aims to develop a combined dynamic characteristic model for both orifice-type and pipe-type air springs, which newly considers the viscoelasticity of bellows and the frequency- and amplitude-dependency of air damping. Firstly, experiments are conducted to study the dynamic characteristics of air springs. Then a combined analytical model is developed based on thermodynamic theory. The generation mechanism and criteria for resonance peaks in dynamic stiffness are illustrated. Further, model parameters are identified using the ellipse features of Nyquist diagrams. The predicted stiffness and loss angle of ASAC are compared with measured results for validations. Finally, the calculated results of the proposed model are compared with that of three other common models in the reported literature. The results show that the proposed models are more accurate and are generated for both orifice-type and pipe-type air springs.