PSI - Issue 75

Alberto Campagnolo et al. / Procedia Structural Integrity 75 (2025) 564–571 Alberto Campagnolo, Giovanni Meneghetti/ Structural Integrity Procedia (2025)

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5. Conclusions The Peak Stress Method (PSM) originally developed for the fatigue assessment of as-welded joints, has been recently extended to cover HFMI treated welded joints made of structural steels having yield stress in the range 355 ≤ σ y < 750 MPa and tested by adopting nominal load ratios R equal to 0.1 or 0.5. In the present study, the applicability of the PSM to HFMI treated joints has been extended by analyzing experimental results taken from the literature and generated from longitudinal stiffeners made of a high-strength steel having yield stress in the range 550 ≤ σ y < 750 MPa and tested under uniaxial loading by adopting nominal load ratios in the range 0 ≤ R ≤ 0.8. As a result, three new PSM-based fatigue design curves have been calibrated against the available experimental results by adopting a methodology consistent with the IIW Recommendations. This includes the assumption of a fixed inverse slope of k = 5 and the categorization of FAT classes based on both the steel yield stress and the applied nominal load ratio. The derived PSM-based FAT classes are summarized in Fig. 3. Campagnolo A, Belluzzo F, Yıldırım HC, Meneghetti G (2022) Fatigue strength assessment of as -welded and HFMI treated welded joints according to structural and local approaches. Int J Fatigue 155:106584. https://doi.org/10.1016/j.ijfatigue.2021.106584 Eurocode 3 . (2005) Eurocode 3: Design of steel structures – part 1 – 9: Fatigue. CEN Gómez FJ, Elices M, Berto F, Lazzarin P (2007) Local strain energy to assess the static failure of U-notches in plates under mixed mode loading. Int J Fract 145:29 – 45. https://doi.org/10.1007/s10704-007-9104-3 Haagensen PJ, Maddox SJ (2013) IIW Recommendations on Methods for Improving the Fatigue Strength of Welded Joints - IIW-2142-110. Woodhead Publishing Hobbacher AF (2016) Recommendations for Fatigue Design of Welded Joints and Components. IIW Collection. Springer International Publishing Kirkhope KJ, Bell R, Caron L, et al (1999) Weld detail fatigue life improvement techniques. Part 1: review. Mar Struct 12:447 – 474. https://doi.org/10.1016/S0951-8339(99)00013-1 Kudryavtsev Y, Trufyakov V, Mikheev P, et al (1994) Increasing the fatigue strength of welded joints in cyclic compression. In: IIW Annual assembly. IIW Doc. XIII-1596-94. Paris Lazzarin P, Berto F (2005) Some expressions for the strain energy in a finite volume surrounding the root of blunt V-notches. Int J Fract 135:161 – 185. https://doi.org/10.1007/s10704-005-3943-6 Lazzarin P, Berto F, Zappalorto M (2010) Rapid calculations of notch stress intensity factors based on averaged strain energy density from coarse meshes: Theoretical bases and applications. Int J Fatigue 32:1559 – 1567. https://doi.org/10.1016/j.ijfatigue.2010.02.017 Lazzarin P, Tovo R (1998) A notch intensity factor approach to the stress analysis of welds. Fatigue Fract Eng Mater Struct 21:1089 – 1103. https://doi.org/10.1046/j.1460-2695.1998.00097.x Leitner M, Simunek D, Shah SF, Stoschka M (2018) Numerical fatigue assessment of welded and HFMI-treated joints by notch stress/strain and fracture mechanical approaches. Adv Eng Softw 120:96 – 106. https://doi.org/10.1016/j.advengsoft.2016.01.022 Livieri P, Lazzarin P (2005) Fatigue strength of steel and aluminium welded joints based on generalised stress intensity factors and local strain energy values. Int J Fract 133:247 – 276. https://doi.org/10.1007/s10704-005-4043-3 Marquis GB, Barsoum Z (2016) IIW Recommendations for the HFMI Treatment. Springer Singapore, Singapore Marquis GB, Mikkola E, Yildirim HC, Barsoum Z (2013) Fatigue strength improvement of steel structures by high-frequency mechanical impact: proposed fatigue assessment guidelines. Weld World 57:803 – 822. https://doi.org/10.1007/s40194-013-0075-x Meneghetti G, Campagnolo A (2020) State-of-the-art review of peak stress method for fatigue strength assessment of welded joints. Int J Fatigue 139:105705. https://doi.org/10.1016/j.ijfatigue.2020.105705 Meneghetti G, Lazzarin P (2007) 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 30:95 – 106. https://doi.org/10.1111/j.1460-2695.2006.01084.x Radaj D, Sonsino CM, Fricke W (2006) Fatigue Assessment of Welded Joints by Local Approaches, 2nd edn. Woodhead Publishing, Cambridge Statnikov E, Shevtsov U, Kulikov V (1977) Ultrasonic impact tool for welds strengthening and reduction of residual stresses. Sci Work Metall SEVMASH, USSR 92:27 – 29 Yildirim HC, Marquis GB (2014) Notch stress analyses of high-frequency mechanical impact- improved welds by using ρ f = 1 mm and ρ f = ρ + 1 mm approaches. Fatigue Fract Eng Mater Struct 37:561 – 569. https://doi.org/10.1111/ffe.12139 References