An approach to evaluate the service life of rubber springs used in rail vehicle suspensions

The stress-endurance (S-N) method has been widely used in metal fatigue in the railway industry over many years. However, when this method is applied to rubber-like materials, it seems not as successful as when it is applied to metallic materials. Recently, an integrated fatigue evaluation programme has been carried out with the aim of improving the design of antivibration components in response to the increasing demands of the rail operating environment. This programme will also make simulations more reliable and relevant to industrial applications, especially for the fatigue design of rubber springs used in rail vehicle suspensions. The continuum mechanics (total life) approach has been used to characterize the fatigue life in terms of the cyclic stress range (S-N curve). It is suggested that the effective stress, sigma(f), can be used as a parameter (taking three principal stress ranges into consideration) to evaluate fatigue failure. The initial verification of this approach has been carried out on two types of rubber spring. The results have shown good agreement between the fatigue test of the components and the simulation based on this approach.