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S. Seichter, V. Archodoulaki, T. Koch, W. Fidi, A. Holzner, S. Robin:
"Experimental survey of approaches to estimate the uniaxial fatigue life of industrial rubbers";
Talk: 9th European Conference on Constitutive Models for Rubbers, Prag, Tschechien; 2015-09-01 - 2015-09-04; in: "Constitutive Models for Rubber IX", B. Marvalová, I. Petríková (ed.); CRC Press, London (2015), ISBN: 978-1-138-02873-9; 433 - 438.

Many different models can be found to predict the fatigue life of rubber under cyclic loading. The models can be categorised in two overall approaches: the crack nucleation approach and the crack growth approach. The crack nucleation approach focuses on the prediction of the fatigue life by using the history of stresses and strains of the material. The results are used for either numerical or analytical estimation of the fatigue life. The crack growth approach explicitly considers the growth of pre-existing flaws. It has been used to predict the uniaxial fatigue life from crack growth measurements.
The different models are analysed in recently published literature surveys but it is also important to compare the models experimentally for application-relevant compounds. Almost all of the studies regarding fatigue life or crack growth behaviour of elastomers use model compounds consisting of one or maximal two polymer types. In the present work the fatigue lives of two application-relevant rubber compounds are investigated containing the same amount of SBR, NR and BR and different types and amount of carbon black.
Two testing machines are used to investigate fatigue life and crack growth. An electrically driven machine is used to measure the fatigue life of rubber compounds. It is provided with an optical measurement which automatically takes picture in order to detect superficial cracks. A hydraulic testing machine is used to do fatigue life measurements under high loads and to determine the crack growth behaviour. It is equipped with both an optical measurement system and an image processing system which is used for crack growth measurements. For a better coherence between the fatigue life and crack growth measurements the same pure shear specimen shapes are used for both experimental set-ups since the behaviour (e.g. crack growth behaviour) of rubber is strongly dependent on the specimen geometry.
The measurement set-up and its advantages and disadvantages are presented and the estimations of fatigue life with the most relevant models are analysed. The restriction is to use analytical models so that the models can be easily applied without Finite Element calculations. Furthermore, the effect of the two different compound compositions on heat build-up, hysteresis, crack growth behaviour and subsequently fatigue life are analysed.

mechanical fatigue, crack nucleation, crack growth, uniaxial fatigue life, measurement set-up, industrial rubber

http://dx.doi.org/10.1201/b18701-75