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 paper 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, where 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.

Figures (14)

• Figure 1: Schematic of the virtual fields method with automated parameterisation. The dashed box encloses the core VFM which, as previously described, identifies a map of constitutive parameters that best satisfies stress equilibrium for a particular spatial parameterisation. The outer loop introduces automated parameterisation.
• Figure 2: Visualisation of the univariate (upper) and bivariate (lower) Gaussian basis functions defined using the table parameters.
• Figure 3: Plot showing the superposition of 1D Gaussian basis functions.
• Figure 4: Schematic of slice used for the force reconstruction error virtual fields.
• Figure 5: Schematic of the virtual mesh used to construct equilibrium gap virtual fields, and associated virtual displacements and strains for the [1,1] virtual displacement of the central node.