| Super
net keeps Pharaohs in place
Several of the world’s best
known cultural treasures are located in areas prone to earthquakes.
A new metal alloy will secure their existence.
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PROTECTING
MONUMENTS:
The statues known as the Colossi of
Memnon near Luxor are irreplaceable
works of art: from now on they will
be better protected against earthquakes.
Contact: Casper van der Eijk,
SINTEF Materials and Chemistry
Tel: +47 73 59 68 57
Email: casper.eijk@sintef.no |
| Photo: GV Press |
Egyptian Pharaohs, Romans and Greeks went
to great lengths to be remembered in the future by building monuments
which are today of enormous cultural and historical value. Research
scientists want to protect these irreplaceable works of art in the
Mediterranean from earthquakes. The solution can be a super elastic
metal alloy that remembers its original form even if it is deformed.
Metal wires can either be entwined as a safety
net around the monument or used to strengthen elements inside it.
But first the research scientists need to find the perfect balance
between the alloy metals’ properties. This will take place
in a laboratory in Trondheim under the leadership of SINTEF research
scientist Casper van der Eijk.
INTERNATIONAL JIG-SAW PUZZLE
The project was originally initiated by Italian professor Fabio
Casciati from the University of Pavia in northern Italy. Together
with structural engineers, seismologists and material scientists,
he is working on a project that can extend the lives of our cultural
treasures.
“Our job is to solve the material technological
piece of the jig-saw puzzle,” says van der Eijk. “We
will do this by strengthening monuments with our so-called Shape
Memory Alloys.”
This is an alloy that consists of titanium
and nickel (Ti-Ni). The alloy has the property that it returns to
its original form despite being deformed. But this occurs only under
special temperatures. In addition, the metal is super elastic. That
means it can stretch more than usual metals because the crystal
structure in Shape Memory Alloys can be changed. In such a process,
during an earthquake parts of the energy are converted to heat.
“Wires of such materials will, therefore,
function as an effective shock absorber,” explains van der
Eijk.
DESERT PROBLEMS
The metal has the same strength as steel and can stretch up to seven
percent, but nevertheless returns to its original form – if
the temperature is stable. Temperature changes are a particular
challenge for research scientists in this project. Many of the monuments
are located in desert areas where it can be very hot during the
day are equally as cold at night. In such conditions, the metal
will perform as it should only during parts of a typical 24-hour
period.
“An Italian research team has worked
on solving the problem with temperature changes by connecting a
cooling system to the metal. That would be both expensive and complicated,
in part because the device would be reliant on electricity to function,”
says van der Eijk.
The Norwegian research scientists have now
come up with a more simple solution for the problem: they will attempt
to find several alloys that react under different temperatures and
join several threads with different properties in one wire. An important
factor will be to keep the wires slim enough. Naturally, historical
monuments require support that is not too visible. An extra bonus
with this solution is that the metal is maintenance free because
it does not corrode.
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Photo: SINTEF
MEMORY METAL: Norwegian
scientists will use several alloys with different properties
in a single wire. |
MODELLING
SINTEF is now underway with finding and characterising the different
alloys of titanium and nickel. The starting point for the work is
an alloy that consists of an equal amount of the two metals. The
research scientists will now gradually change the composition to
find the optimal solution for Shape Memory Alloys that don’t
forget even if the day is hot and the night is cold. The next stage
will be mechanical testing and analysis under the microscope.
“Factors like how the metal is produced,
which heat treatments they have undergone and how many small impurities
they contain are also relevant,” he says. The next stage will
then be for the results to be modelled on a computer program taking
into account tests, variables and mechanical tests on the different
monuments. This will assist with the continued work to find the
correct alloys to protect several historical monuments in the future.
“What will such protection cost?”
“We must count on each metre of metal costing around 200 kroner.
But we need to join several, something that quickly brings the metre
price up to 2000 kroner. But if you do it right the first time,
it won’t be expensive when you consider that these are ancient
monuments that cannot be replaced.”
Christina B.Winge
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