Techreport,
LABORATORY REPORT 774 mm2 aluminium alloy conductor exhibiting a rich occurrence of flakes in the wires Fatigue tests
(1979)
Abstract
The Swedish State Power Board has previously carried out fatigue tests on
a 774 mm
2
aluminium alloy conductor exhibiting a rich occurrence of flakes
in the wires. The conductor was tested in the bare state under the action
of pulsating tensile loads. In these tests all wire fractures developed
from flakes of varying sizes. Now some fatigue tests under the action of
lexural vibrations have been carried out in order to follow up whether
lakes will have a similar influence when the conductor is stretched over
a stringing sheave or equipped with armour rods and a suspension clamp.
Two fatigue tests relating to the group conductor-armour rods-suspension
clamp were also made under the action of pulsating tensile loads.
t is seen from static tests on the wires that the flakes had such severity
that the static strength of the wires, as well as the ductility, was affected.
n spite of this fact the flakes proved to be of secondary importance from the
atigue point of view under these combined conditions. Fretting was found
o be the dominant factor in the development of fatigue fractures.
owever, taking into account the complex nature of conductor fatigue this
eport is not establishing any acceptance criteria to be applied commercially
to flakes and other imperfections. The relevant standard specifications and
dditional quality control specifications, if any, are to be followed as well
s good praxis.
