9th Annual Student Colloquium & Poster Session.
In tire industry, fatigue crack propagation in elastomers is investigated to improve the service life of products. Natural rubber (NR) is a key compound in tires, because of its remarkable mechanical properties and more particularly its excellent resistance to fatigue crack growth as compared to synthetic rubbers. To explain these good properties, the literature often mentions the strain-induced crystallization phenomenon that takes place at the tip of fatigue cracks in NR.
In this study, an original experimental set-up that couples synchrotron radiation with a homemade fatigue machine has been developed to study strain-induced crystallization in the neighbourhood of fatigue cracks in NR. During uninterrupted fatigue tests, recording of X-ray diffraction patterns is synchronized with the cyclic loading to perform a ffmappingli of WAXD measurements which leads to a 2D spatial distribution of crystallinity at crack tip.
As results, we present the characteristics of the crystallized zone measured in front of a crack in filled natural rubber samples (50phr of N347 carbon black). We investigate in particular the influence of loading conditions (level of cyclic stretching and non relaxing loading conditions) on the size of the crystallized zone, in order to relate it to the macroscopic measurements of crack propagation rates.