Development of a methodology for the automated spatial mapping of heterogeneous elastoplastic properties of welded joints

Abstract

Knowledge of the mechanical properties of materials is required for the design and analysis of engineering products, however, the characterisation of heterogeneous properties using traditional techniques is limited by spatial resolution or insufficient reliability. This thesis presents a novel methodology for the characterisation of heterogeneous mechanical properties by extending the virtual fields method through the automated spatial parameterisation of constitutive parameters. Collaboration with the United Kingdom Atomic Energy Authority provided this project with an application focus on the characterisation of the spatially-varying, elastoplastic mechanical properties of welded joints. The developed methodology enables the novel characterisation of welds with assorted geometries, varied loading configurations and dissimilar materials.

Numerical verification of the developed method was performed using synthetic data equivalent to that obtained experimentally using optical measurements, however the kinematic fields are known and controlled. The results confirm that the proposed approach converges towards the target parameter maps without any a priori information on the distribution of the properties, successfully demonstrating the established methodology as a proof of concept.

Experimental characterisation was attempted on dissimilar metal laser-welds between stainless steel 316L and grade 91 steel in both butt-joint and T-joint configurations. This experimental work was essential in ensuring the methodology was developed in line with real-world mechanical testing.

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Identifiers

ORCID for Robert Hamill: orcid.org/0000-0001-7800-3170

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

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

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