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Applications of digital image correlation to study damage and behavior of filled elastomers
This study is part of the AMUFISE project (ANR, program " Matériaux Fonctionnels et Procédés Innovants") driven by the Michelin manufacture. It is focused on the study of material behavior, damage and crack propagation in filled elastomers using digital image correlation (DIC) as a kinematic measurement technic.
The volume variation measurements on a sample under uniaxial cyclic loading shows a loss of incompressibility beyond a strain threshold. These results confirm those from a parallel study on the same materials using small angle X-ray scattering and showing a cavitation at a nanoscale. We also highlighted an anisotropy in the material behavior.
A new methodology to identify behavior law parameters in an inhomogenious test was proposed. The principle is to minimise the difference between displacement fields measured using DIC and displacements fields obtained with a Finite Element program in which the limit conditions come from the measurments. We show at convergence that the difference between these two fields (of very low amplitude) essentially contains noise from the kinematic measurements. This technic does not depend on the complexity of the law used and is non-inrusive to the industrial finite element program.
The study on crack propagation also benefist from the DIC measurements. Howewer, it appears that discriminant scales to highlight blunting phenomena and the crack propagation stabilisation are under 50-100 µm.