Comparison of two different modeling approaches to describe the non‐linear viscoelastic behavior of filled rubber material

Abstract

AbstractThis contribution presents the characterisation of an incompressible carbon black‐filled elastomer as one characteristical example for highly filled rubber material. The material model is developed with respect to uniaxial tension data. The experiments show that a strongly pronounced non‐linear viscoelastic material behavior is present and the most important characteristic is the extremely long relaxation time which has to be taken into account. These long relaxation times are also visible in cyclic tests, where a pronounced hysteresis loop appears even for the slowest possible strain rates [1,2].In the material's characterization two different model approaches are realized. As a first approach the behavior is represented by a pure viscoelastic model. Since all the deformations are reversible for a stress‐free relaxation, no plasticity parts are included in the model. In order to display the non‐linearities process‐dependent material parameters have to be applied. Hence, the resulting coupling of different material parameters yields a complex parameter identification.For a more effective identification process, a second approach is provided describing the interaction of the filler particles. The friction of the fillers during deformation results in a statical hysteresis, which does not depend on the strain rate. Therefore, special attention is turned towards the behavior of the hysteresis loops that are observed, similar to the description of Vandenbroucke et al. [3]. Therein, in a rheological model, some Prandtl‐elements, consisting of a friction element and a spring are added to the classical viscoelastic model. This results in a model, which does not need any process‐dependency. Hence, the identification process can be simplified. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)