95th' Anniversary of the TITANIC DISASTER

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95th. Anniversary of the TITANIC DISASTER
14th. April 1912
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Unsinkable 16 watertight compartments.
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Sank in less than three hours. Lifeboat space
had been provided for only about half of the
passengers and crew Californian, close to the
scene, had not come to the rescue because its
radio operator was off duty and asleep.
Reforms lifeboat space for every
person on a ship lifeboat drills
full-time radio watch while at sea an
international ice patrol.
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Why did the Titanic sink so easily?
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Robert D. Ballard
Professor of OceanographyDirector, Institute
for Archaeological Oceanography University of
Rhode Island
Discovered the wreck of the Titanic in 1985
"All kids dream a marvelous image of what they
want to do. But then society tells them they
can't do it. I didn't listen. I wanted to live my
dream."
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Liberty Ships the first all-welded
pre-fabricated cargo ships Mass produced in the
United States. 2,751 Liberty Ships were built
between 1941 and 1945 Only two now remain
afloat Many of the remainder were destroyed by
cracking of the type shown.
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What was the cause of the failure of the Liberty
ships?
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?
Silent puncture
Two ways for the tire/tube to fail
Noisy burst
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Balloon Experiment
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Surprise !!!
A balloon bursts when all we are trying to do is
to make a small hole ???
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A.A. Griffith (1893-1963)
Phenomena of rupture and flow in solids,
Philosophical Transactions of the Royal Society
of London, A221, 163-198 (1921)
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Experiment on paper tearing
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Two types of fracture Ductile
fracture Brittle fracture
Q Which of the two absorb more energy?
stress
stress
Brittle
ductile
strain
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Charpy Impact Test
ductile
brittle
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Ductile-to-brittle transition
?y (bcc)
?f
?f
?y lt ?f
?y (fcc)
?y gt ?f
ductile
brittle
T
TDBTT
T
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Ductile-to-brittle transition

• FCC materials do not show DBT
• Good for cryogenic applications
• Stainless steel (austenite fcc)containers
• for Liq O2 rocket fuel
• mild steel not good (? bcc)

• Fine grain size give lower transition temperature
• High strain rate increase the transition
  temperature
• 4. Notches increase the transition temperature

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Protection against fracture
Reduction in cross-section glass fiber
Introduce compressive stresses in the surface
Tempering of glass Ion- exchange of glass
Carburization of steel (chapter 8)
Fine-grains in ceramic glass-ceramics discussed
in chapter 9 Reduction of sulphur in steel