The Simulation of an Automotive Air Spring Suspension Using a Pseudo-Dynamic Procedure

Abstract

This paper describes a numerical solution to characterize the deformation of a bellows-type air spring for automotive suspensions. In a first step, the shell structure is modeled as a practically inextensible membrane that has virtually no bending stiffness; the structure has only a pneumatic-elastic deformation due to the compressibility of the pressurized air. In a second step, a finite element modeling of the device using a commercial code is carried out in order to validate the first model. Complementing this work, an experimental procedure based on a pseudo-dynamic technique was implemented to simulate the behavior of the pneumatic suspension bellows subjected to dynamic loads. The method consists of a combined numeric/experimental procedure simulating a suddenly applied load. had some technical detail, describing the essential air circuit architecture, components, and quantitative settings of a pneumatic suspension for production. By 1950 onwards, air suspensions experienced a large development as many transportation companies decided to implement those suspension systems in their vehicles, which resulted in quiet and smooth running.The actual performance of automotive bellows suspension has reached an important technologic standard through the implementation of pressure/stability control electronic hardware in railway coaches, as reported by Quaglia and Sorli [3].Normally, the structural analysis and dynamic testing of bellows air springs are not presented with detail due to manufacturers' strategic restriction of technologic knowledge dissemination; alternatively, university institutions working in automotive engineering share valuable contributions. Examples can be assigned to Löcken and Welsch [4] (from Helmut Schmidt University, DE), who studied the dynamics of bellows air suspensions accounting for the coupled effect of air heating and spring stiffness increase by the coupled effect; the natural frequencies and damping methods were also studied. The shape of the elastic element considered by Löcken and Welsch [4] was not a toroidal shell like the one analyzed in the present work. Such a shape conditioned the spring geometry by the mutual surface contact of the elastomeric membrane and the internal rigid core, giving rise to the non-linear kinematics contact model in the numerical modeling.Among the finite element models of deformable shells conducted so far, it is worth mentioning the one presented by Yilong Zhang et al. [5], who modeled suspension bellows as toroidal shells with a coupling of the prescribed deformation and the internal pressure, having used ANSYS ® for the purpose. The objective was to obtain the natural frequencies of a suspension for several internal pressures, verify the non-linear behavior, and implement linearization methods to solve the problem of the evaluation of natural frequencies.Air spring suspensions are mounted in a large number of railway or roadway vehicles and have been a technical success, given their reliable, functional, and robust design. Urban vehicles equipped ...

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