Development of new virtual fields for the non-linear virtual fields method

Abstract

Extraction of material parameters from full-field measurements is an increasingly important part of experimental mechanics. Due to development of full-field techniques, such as digital image correlation, new types of mechanical tests are being developed that lead to a more efficient investigation of materials behaviour. One of the popular techniques for the extraction of material parameters from full-field measurements is the virtual fields method. The virtual fields method is centred around a concept of virtual fields, which are spatial functions that act as a filter for experimental measurements during the identification procedure. The choice of appropriate virtual fields is crucial for tackling the problems of experimental noise and complex structure of the data obtained in an experiment. This project explores a new type of virtual fields, designed to improve the identification of material parameters for non-linear material models with the virtual fields method. The proposed virtual fields are based on the sensitivity of the reconstructed stress field to the values of material parameters allowing them to be automatically generated during the identification. They can be used with any test geometry and material model, which constitutes a very general method that is easily applicable to many static and dynamic tests. In this thesis, the development and testing of the sensitivity-based fields are presented. The method was applied to the identification of material parameters in the context of metal plasticity, in particular, small deformation isotropic plasticity and large deformation anisotropic plasticity. The validation was performed using a series of numerical and experimental tests; a significant improvement was found in terms of the accuracy of identification compared to the standard user-defined virtual used in previous studies.

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Identifiers

ORCID for Alex Marek: orcid.org/0000-0002-2254-3773

ORCID for Fabrice Pierron: orcid.org/0000-0003-2813-4994

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