Development of a Numerical Prediction Method for the Strain Energy Density of Welded Joints Using Structural Stresses Derived from Nodal Forces

This paper describes the numerical prediction of the fatigue strength at the toe of steel fillet-welded joints in conditions of HCF, comparing and integrating results from an energy-based approach based on the Average Strain Energy Density (A-SED) and structural stresses derived using the nodal forces approach (Mesh-Insensitive) on shell FE models. The analysis considers plates of different thicknesses and weld sizes. The proposed method combines the two mentioned approaches to exploit the advantages of both, allowing a fast preliminary investigation of numerous and complex welded joints within a simplified model, with a coarse mesh and no geometric pre-processing required, while keeping a good adherence to the precision benefits given by local energy evaluations. This activity demonstrates a strong correlation between the numerical values obtained from the proposed innovative approach and the results from predictions made using a standard energy-based approach, with significantly lower computational and setup costs. Data processing and calculations are performed using the open-source software Python 3.10 (Software Foundation, Wilmington, DE, USA) to demonstrate the applicability of this method as a quick and ready-to-use “post-process” tool for industrial applications.