The residual stress distribution in three laser welded T-joint configurations of aerospace
aluminium alloys were measured using neutron diffraction and FE-simulation was conducted to
compare with the experimental results. A 2 mm thick AA 6013 T6 sheet (as clip) was welded to a
4.5 mm thick and 400 mm wide AA 6156 T4 base plate (as skin of the airframe). In two samples,
the thickness of the plate was reduced in some areas after welding to produce so-called “pockets”
with the purpose of the weight reduction to resemble the fabrication practise in aircraft industry.
The effect of pocketing process, which produced two different geometries around the clip weld on
the residual stress evolution was analysed. In the plain sample (without pockets), residual stresses
were predicted using the SYSWELD finite element software. The strain measurements on the base
plate were performed at three locations; namely, the middle of the weld length (mid-clip), welding
start (run-in) and end (run-out) locations.
In all welded plates, slightly higher longitudinal tensile residual stresses were detected at the midclip
locations, whereas transverse residual stresses were similar for all locations. In the run-out
location, higher longitudinal tensile residual stresses were present than in the run-in location, which
was the case in our previous results on other samples.
The first results of the SYSWELD FE-simulation of the plain sample were compared with
experimental results. The comparison has shown particularly good agreement for the transverse
stresses. Although the simulation yields higher longitudinal tensile stresses than the experimental
results, the stress distributions were very similar.
Elastic follow-up and relaxation of residual stresses
