PSI - Issue 75

Luca Vecchiato et al. / Procedia Structural Integrity 75 (2025) 602–608 Luca Vecchiato et al. / Structural Integrity Procedia (2025)

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3. Conclusions The Peak Stress Method (PSM) is a fatigue strength assessment technique specifically developed for welded joints. It models the weld toe and root as sharp V-notches with a zero- radius tip (ρ = 0), allowing the use of relatively coarse 2D or 3D finite element meshes to calculate Notch Stress Intensity Factors (NSIFs) based on the singular peak stresses occurring at the notch tip. The fatigue damage parameter is defined in terms of an equivalent peak stress range, obtained through the averaged Strain Energy Density (SED) criterion. Recently, the PSM has been extended to deal with variable amplitude multiaxial stress histories. In this study, the VA formulation of the method is applied to the fatigue strength evaluation of tube-to-flange arc-welded joints made from extruded and peak aged AlSi1MgMn alloy tested under constant and variable amplitude in-phase and out-of-phase combined bending and torsion loadings. Results confirm the method’s reliability, with experimental fatigue data falling inside the PSM based design scatter band under both constant and variable amplitude loading conditions. References [1] EN, Eurocode 3: Design of steel structures – part 1 – 9: Fatigue, (2005). [2] EN, Eurocode 9: Design of aluminium structures - Part 1-3: Structures susceptible to fatigue, (2007). [3] A.F. Hobbacher, J. Baumgartner, Recommendations for Fatigue Design of Welded Joints and Components, Third, Springer Nature Switzerland, Cham, 2024. https://doi.org/10.1007/978-3-031-57667-6. [4] G. Meneghetti, A. Campagnolo, State-of-the-art review of peak stress method for fatigue strength assessment of welded joints, Int J Fatigue 139 (2020) 105705. https://doi.org/10.1016/j.ijfatigue.2020.105705. [5] P. Lazzarin, R. Tovo, A Notch Intensity Factor Approach to the Stress Analysis of Welds, Fatigue Fract Eng Mater Struct 21 (1998) 1089 – 1103. https://doi.org/10.1046/j.1460-2695.1998.00097.x. [6] M.L. Williams, Stress singularities resulting from various boundary conditions in angular corners of plates in tension, J Appl Mech 19 (1952) 526 – 528. [7] B. Gross, A. Mendelson, Plane elastostatic analysis of V-notched plates, International Journal of Fracture Mechanics 8 (1972) 267 – 276. https://doi.org/10.1007/BF00186126. [8] P. Lazzarin, R. Tovo, A unified approach to the evaluation of linear elastic stress fields in the neighborhood of cracks and notches, Int J Fract 78 (1996) 3 – 19. https://doi.org/10.1007/BF00018497. [9] G. Meneghetti, P. Lazzarin, Significance of the elastic peak stress evaluated by FE analyses at the point of singularity of sharp V-notched components, Fatigue Fract Eng Mater Struct 30 (2007) 95 – 106. https://doi.org/10.1111/j.1460-2695.2006.01084.x. [10] G. Meneghetti, P. Lazzarin, The Peak Stress Method for Fatigue Strength Assessment of welded joints with weld toe or weld root failures, Welding in the World 55 (2011) 22 – 29. https://doi.org/10.1007/BF03321304. [11] P. Lazzarin, R. Zambardi, A finite-volume-energy based approach to predict the static and fatigue behavior of components with sharp V-shaped notches, International Journal of Fracture 2001 112:3 112 (2001) 275 – 298. https://doi.org/10.1023/A:1013595930617. [12] P. Lazzarin, P. Livieri, F. Berto, M. Zappalorto, Local strain energy density and fatigue strength of welded joints under uniaxial and multiaxial loading, Eng Fract Mech 75 (2008) 1875 – 1889. https://doi.org/10.1016/j.engfracmech.2006.10.019. [13] P. Livieri, P. Lazzarin, Fatigue strength of steel and aluminium welded joints based on generalised stress intensity factors and local strain energy values, Int J Fract 133 (2005) 247 – 276. https://doi.org/10.1007/s10704-005-4043-3. [14] A. Campagnolo, L. Vecchiato, G. Meneghetti, Multiaxial variable amplitude fatigue strength assessment of steel welded joints using the peak stress method, Int J Fatigue 163 (2022) 107089. https://doi.org/10.1016/j.ijfatigue.2022.107089. [15] G. Meneghetti, A. Campagnolo, D. Rigon, Multiaxial fatigue strength assessment of welded joints using the Peak Stress Method – Part I: Approach and application to aluminium joints, Int J Fatigue 101 (2017) 328 – 342. https://doi.org/10.1016/j.ijfatigue.2017.03.038.