[SY-H6] Modelling of Influence of Fatigue Damage on Oxygen Diffusion in Rubbers
Rubbers are frequently used in vibration isolation, e.g. as the material for engine mounts or tram wheel suspension segments. These parts are subjected to periodical mechanical loading and to the effects of the environment, such as temperature or chemical reactions. Depending on the nature of the structure changes induced by the environment, physical or chemical ageing may be distinguished (see e.g. [1]). Chemical ageing is governed by the consumption of oxygen, which in turn depends on its transport by diffusion.
Both damage and ageing lead to changes in mechanical properties, each of the phenomena, however, takes place at a different length scale. This contribution is focused on the influence of fatigue damage on the diffusion of oxygen. The central assumption is that the formation and growth of microcracks influence the paths of the gas molecules, which manifest itself as the coefficient of diffusivity on the macroscopic scale. We present various examples of crack geometries and the resulting oxygen flux and concentration computed by the finite element method (FEM). These results will be further used to derive a phenomenological model of coupled fatigue damage and diffusion-limited oxidation (DLO). This model will be an extension of an existing model [2], in which, however, no explicit relation for the coupling between fatigue damage and diffusivity is considered.
[1] Herzig, A. , Johlitz, M. and Lion, A. Consumption and diffusion of oxygen during the thermoxidative ageing process of elastomers. Mat.-wiss. u. Werkstofftech, 47: 376-387, 2016.
[2] Heczko, J., Kottner, R. Modelling of ageing and fatigue under large strains. In Computational Mechanics - EXTENDED ABSTRACTS, 2017.
Both damage and ageing lead to changes in mechanical properties, each of the phenomena, however, takes place at a different length scale. This contribution is focused on the influence of fatigue damage on the diffusion of oxygen. The central assumption is that the formation and growth of microcracks influence the paths of the gas molecules, which manifest itself as the coefficient of diffusivity on the macroscopic scale. We present various examples of crack geometries and the resulting oxygen flux and concentration computed by the finite element method (FEM). These results will be further used to derive a phenomenological model of coupled fatigue damage and diffusion-limited oxidation (DLO). This model will be an extension of an existing model [2], in which, however, no explicit relation for the coupling between fatigue damage and diffusivity is considered.
[1] Herzig, A. , Johlitz, M. and Lion, A. Consumption and diffusion of oxygen during the thermoxidative ageing process of elastomers. Mat.-wiss. u. Werkstofftech, 47: 376-387, 2016.
[2] Heczko, J., Kottner, R. Modelling of ageing and fatigue under large strains. In Computational Mechanics - EXTENDED ABSTRACTS, 2017.