Modeling and performance analysis of convoluted air springs as a function of the number of bellows

•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.