Lifetime prediction of carbon black filled elastomers based on the probability distribution of particle using an inelastic and hyperelastic material model

Abstract

In this work, lifetime of carbon black filled elastomers is predicted based on a micro-flaw statistics lifetime concept. Within this concept two material models, the hyperelastic Yeoh model and the inelastic material model of rubber phenomenology (MORPH), are compared. The Yeoh model is chosen as a demonstrator for any hyperelastic material model. This model is not able to reproduce the characteristic material behaviour such as permanent set, softening effects and hysteresis and can only reproduce the nonlinearity of the stress-strain response. To overcome these deficiencies the hyperelastic models are typically fitted to the softening state of the material at a maximal (cyclic) load level. However, the results show that it is not foreseeable, which load level should be used for fitting the model to get a reasonable lifetime prediction. This is even more influenced by the restriction that only one parameter set has to be chosen to represent the inhomogeneous softening state of the material when arbitrary loads are applied. The above-mentioned characteristic properties of filled elastomers can be reproduced by the MORPH model. The lifetime prediction using this inelastic material model shows very good agreement with the measured values. Furthermore, the variable softening within the model adumbrate a good lifetime prediction quality of components with complex geometries.