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• A novel combined model is developed to evaluate the dynamic characteristics of both orifice-type and pipe-type air springs with auxiliary chambers. • The proposed model newly considers the viscoelasticity of rubber bellows and the nonlinearity of airflow damping. • The generation mechanism and criteria for resonance peaks in the dynamic stiffness of pipe-type air springs are theoretically disclosed. 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. [ABSTRACT FROM AUTHOR]

• A time domain model of the air spring with an auxiliary chamber (ASAC) system is developed and validated. • The proposed model disclosed the experimental phenomena of the orifice-type and pipe-type ASAC systems. • Key parameters determining the ASAC system step response are found. The paper aims to establish analytical models for air spring with an auxiliary chamber (ASAC) to study the nonlinear characteristics of ASAC systems in the time domain. A test bench is built for measuring the dynamic characteristics of an ASAC, and the transmitted force of an ASAC is measured if harmonic and transient step displacements are applied. To calculate the transmitted force of orifice-type and pipe-type ASACs, lumped parameter models are developed, and the transmitted force are calculated by using convolution theory. Based on the established models and the measured data, model parameters are identified. The relative error for estimating transmitted force response using the proposed model is less than 6.1% compared with experiment under harmonic excitations. The characteristics that the transmitted force of an orifice-type air spring is monotonically attenuated while that of a pipe-type one is oscillating attenuated under step excitation are explained in the view of physical insight using the proposed models. Finally, a one-degree-of-freedom vibration system that assumes the stiffness and damping is provided with the proposed ASAC model is used to study the transmitted force of the mass element if step displacement excitation is applied to the base. The effects of designed parameters on the transmitted force responses of the vibration system are analyzed. [ABSTRACT FROM AUTHOR]

• A novel modeling method for convoluted air springs is proposed to estimate the vertical stiffness. • Both the effects of bellow's tensile deformation and the asymmetric structural features are considered in the proposed model. • The proposed model is fully solved and derived to a unified model as a function of the number of bellows. The article presents a novel mathematical model to analyze the performance of convoluted air springs (CAS) with different numbers of bellows. The proposed mathematical model considers both the effects of bellow's tensile deformation and the asymmetric structural features. Some key parameters such as effective area, volume, and their variation rates are derived based on geometric analysis to establish the analytical model of the vertical stiffness and maximum outer diameter. Three types of CAS with single, double, and triple bellows are designed and manufactured for testing the performances. The developed model presented in this paper is compared with another three analytical models based on different assumptions and simplified methods by comparing the estimated stiffness and maximum outer diameter. The comparison demonstrates that the proposed model in this paper has higher accuracy than that of the others and has a uniform formula as a function of the number of bellows to calculate performances of CAS. It is also shown that for the simplified model, ignoring the tensile deformation of the bellows or the asymmetry of the model will introduce large calculation errors for the stiffness up to 10.96%. The reasons for the estimated errors compared with experiment are analyzed at the end of the article. [ABSTRACT FROM AUTHOR]