• Ole Skjerninge Hermansen
  • Rasmus Sørensen
4. term , Design of Mechanical Systems, Master (Master Programme)
Current fatigue assessment of welded joints is
based on fatigue curves in which several effects
known to influence the fatigue strength, such as
the weld geometry, residual stresses, and material
variations are included. The present work aims
to investigate the influence of including the weld
geometry, as obtained by laser scanning, on
uncertainty in fatigue assessment.
The investigation involves 33 butt welds in
S690 and 32 butt welds in S960, subjected to
low cycle fatigue. Laser scanning is conducted
on each specimen to construct a finite element
model incorporating the actual weld geometry.
Various fatigue indicators are explored to assess
their effectiveness in reducing fatigue uncertainty,
combined with a nonlocal model to account
for the stress distribution. Using a Weibull
distribution based on the weakest-link theory, the
performance of the fatigue indicators in reducing
uncertainty is evaluated.
The highly stressed volume nonlocal model
with maximum principal stress exhibited the
lowest uncertainty, with scatter indices of 3.69 for
S690 and 3.63 for S960, compared to higher values
of 5.11 and 8.42 for the nominal stress approach,
respectively. These findings demonstrate the
influence of weld geometry on uncertainty in
fatigue assessment of butt welded joints.
The study also reveals a relationship between
the local stress and weld toe radius, demonstrating an exponential stress-raising effect as the weld
toe radius decreases. However, the influence of
other geometric weld features on local stress could
not be explicitly distinguished due to a lack of
clear correlation.
Publication date1 Jun 2023
Number of pages82
ID: 532384375