Multiscale displacement field measurement using digital image correlation: Application to the identification of elastic properties
Résumé
As any Digital Image Correlation (DIC) method, Finite-Element(FE) based DIC methods lead to uncertainties which are related to the spatial resolution (in pixel / element). To overcome the tricky and well-know compromise between spatial resolution and uncertainty, a multiscale approach to FE-DIC is proposed. Additional near-field images are used to improve locally the resolution of the measurement for a given measurement mesh. An automatic and accurate estimation of the nearfield / farfield transformation is obtained by a dedicated DIC based method, in order to bridge precisely the measurement performed at both scales. This multiscale measurement is then associated to a multiscale Finite Element Model Updating (FEMU) identification technique. After being validated on synthetic test cases, the method is applied to a tensile test carried out on an open-hole specimen made of glass / epoxy laminate. The four in-plane orthotropic elastic parameters are identified at different levels of loading. Results shows that the multi-scale approach greatly improves the uncertainty of both the measured displacement and the identified material parameters.
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