Fatigue crack growth in aluminium alloy structures

Nosair, SIM

Abstract

Fatigue cracks have been reported in the super structure of the
surface ships in the navy. Repair techniques have been proposed
and applied on compact tension specimens. Such techniques were;
either by creating compressive residual stresses using welding
anisotropy, local plastic deformation and spot heating. Or,
constraining the crack tip using tightened bolt or steel/carbon
fibre patches.
Complete F.C.G. data were obtained for the metal in the
as-rolled and welded conditions. A metallurgical study has also
been made. Fractography, the influence of residual stresses and
second phases have been studied.
The study showed that superior crack resistance was obtained from
spot heated specimens, which were very simple to prepare.
Considerable retardation was also obtained using welding
anisotropy, local plastic deformation and tightened bolts.
Patching seems to provide limited improvement.
The influence of compressive residual stress was found to improve
the crack resistance. The influence of the inclusions was found
to depend on their morphology. Medium sized and homogeneously
distributed inclusions provided a retarding effect on the crack
speed. More inclusion interaction was reported in the presence
of residual stresses.

Citation

Nosair, S. Fatigue crack growth in aluminium alloy structures. (Thesis). Salford : University of Salford

• Thesis Type: Thesis
• Deposit Date: Oct 3, 2012
• Award Date: Jan 1, 1986