High-frequency mechanical impact (HFMI) is an effective post-weld treatment that enhances fatigue strength by inducing compressive residual stresses, localized strain hardening, and increasing weld toe radii. The peak stress method (PSM) was recently extended to evaluate the fatigue strength of HFMI-treated steel joints under uniaxial loading through dedicated design curves, calibrated on experimental data covering yield stress in the range 335 <= sigma(y) < 750 MPa and load ratios -1 <= R <= 0.8. This study further extends the applicability of the PSM by considering additional 750 experimental data taken from the literature. These data refer to joints made of steels (235 <= sigma(y) <= 1100 MPa), tested under load ratios -1 <= R <= 0.8. Overall, 19 new PSM fatigue design curves with inverse slope k = 5 and FAT class in the range 168-345 MPa, that is, between +8% and +121% versus as-welded FAT = 156 MPa, have been fitted. Finally, IIW-based correction factors transferred to PSM yielded conservative estimations across the dataset.
Fatigue Lifetime Assessment of HFMI-Treated Welded Joints According to the Peak Stress Method
Campagnolo A.;Meneghetti G.
2026
Abstract
High-frequency mechanical impact (HFMI) is an effective post-weld treatment that enhances fatigue strength by inducing compressive residual stresses, localized strain hardening, and increasing weld toe radii. The peak stress method (PSM) was recently extended to evaluate the fatigue strength of HFMI-treated steel joints under uniaxial loading through dedicated design curves, calibrated on experimental data covering yield stress in the range 335 <= sigma(y) < 750 MPa and load ratios -1 <= R <= 0.8. This study further extends the applicability of the PSM by considering additional 750 experimental data taken from the literature. These data refer to joints made of steels (235 <= sigma(y) <= 1100 MPa), tested under load ratios -1 <= R <= 0.8. Overall, 19 new PSM fatigue design curves with inverse slope k = 5 and FAT class in the range 168-345 MPa, that is, between +8% and +121% versus as-welded FAT = 156 MPa, have been fitted. Finally, IIW-based correction factors transferred to PSM yielded conservative estimations across the dataset.
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