Quantitative Review of Critical Plane Criteria and Stress Analysis Approaches for Multiaxial Fatigue of Welded Joints

This quantitative review evaluates the effectiveness of stress-based critical plane criteria, specifically Findley's criterion, the approach due to Carpinteri–Spagnoli (CS), and the Modified Wöhler Curve Method (MWCM), in assessing fatigue strength in aluminum and steel welded joints subjected to constant amplitude (CA) and variable amplitude (VA) multiaxial loading. These criteria were analyzed alongside stress analysis approaches, including nominal stress (NS), hot-spot stress (HSS), effective notch stress (ENS), and the Theory of Critical Distances–Point Method (TCD PM). Results confirm that all criteria effectively estimate fatigue life for steel welded joints under CA loading, with MWCM combined with HSS proving most accurate. For aluminum joints, estimations showed greater conservatism and scatter, highlighting the need for further experimental data to improve accuracy. Experimentally calibrated constants significantly enhanced prediction reliability. Future research should refine these criteria for diverse aluminum grades and thicknesses, ensuring accurate estimations and robust alternatives to established codes.