Transcript LIBERTY_SHIPS[1][1].ppt

Liberty Ships built to fill shipping
gaps during WWII
•Quick and cheap to build, used
welding instead of rivets
•Built in huge volume due to
demand
•Hence lack of experienced staff
•1 in 3 failed over its life
FAILURE
•Dramatic
•Thought
and sudden failure
to be enemy fire at first
•Investigation
proved impossible
until failure occurred at port
•Survived
design life of 5 years in
many cases
Only seamed to fail in very cold
waters
Occurred at places of
concentration of stress
Fatigue considered likely
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Steel grade not the cause
Welding technique vulnerable to brittle behaviour,
unlike rivets
Nil Ductile Transition Temperature found to be
transition between ductile and brittle behaviour
Low notch (fracture toughness)
Quality of welding called into question
Design features that were expedient weren't
always best
Loading and unload of heavy loads
Shipping conditions to a lesser extent
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Design that doesn't cause concentration of
stress
Rivets at vulnerable points
Alteration of properties of steel e.g.
addition of oxidisation element
Research into NDTT
Better quality assurance both in
construction and sailing