Creep modelling and unloading evaluation of the rubber suspensions of rail vehicles

Abstract

An engineering approach to the evaluation of the creep response and unloading behaviour of the rubber suspension systems used on rail vehicles is presented. A damage function is introduced that links the creep in the rubber to a structural change that leads to a degradation of the material over time. Hence, a hyper-elastic model is not only related to the loading condition, but also it is a function of the elapsed time; thus, a creep evaluation can be performed at the design stage using existing models that are widely used in the rail industry. A typical rubber suspension component, a Metacone spring mount, was selected to validate the proposed approach. It has been shown that the predictions offered by the proposed model are consistent with the creep history found in experiments. In addition, mechanical unloading modelling using a rebound energy approach is also presented and the results, when compared with experimental data, indicate that the main characteristics of the unloading are captured. It is suggested that the proposed methods may be used in the design of rubber suspensions.