This paper compares the calculated fatigue life with the tested life, for a
n embedded crack in the friction weld between two axially loaded rods. The
initial crack is caused by lack of fusion in the centre of the friction wel
d. The radius for the initial circular crack is 5-6 mm. The stress intensit
y factors for the crack are calculated with the weight function method. It
was found that a relatively high axial tensile residual stress must exist i
n the centre, to get the crack to grow sufficiently fast. An approximation
for the residual stress distribution is used in the calculation. The calcul
ation gives about 30% longer median lives than the fatigue tests. That migh
t depend on uncertainties in material data and/or the fact that the tensile
stress in the centre is higher than expected. The paper also shows that th
e integrals in the weight function method can be solved by a standard mathe
matics program. (C) 2000 Elsevier Science Ltd. All rights reserved.