S-N Lines for Welded Thin Joints — Suggested Slopes and FAT Values for Applying the Notch Stress Concept with Various Reference Radii

摘要: An assessment of thin welded structures with actual IIW design lines results in an overestimation fatigue lives (strengths) at high load levels and a conservative estimation low levels, many cases, independently the applied approach (nominal, structural or notch stress). This is mainly due to slopes S-N line k = 3.0 for normal 5.0 shear stresses, which are valid thick stiff structures. To overcome this inconsistency flexible structures, 7.0 stresses suggested, keeping already known FAT values derived stress concept variants rref 1.0, 0.3 0.05 mm, respectively. However, slope not only determined by plate thickness; it result interaction between thickness, local geometry (stress concentration), stiffness, loading mode last but least residual stresses. complexity makes difficult identify driving parameters predict cases.