french institute of science and technology for transport ... - Ifsttar

Patents
Shape-memory dampers
The possibility of fatigue-free cables?
Civil engineering structures are subjected to very testing
service conditions. Rain, wind, salt from the sea,
pollution, temperature variations, mechanical loads …
a whole list of external factors can cause cables to vibrate
and shorten the lifetime of structures.
Devices that are currently operating on structures such
as cable dampers, cable ties and extruded pipes that cover
the stay cables can attenuate and increase the frequency of
these vibrations. However, these devices have less impact
on vibrations with high frequencies and high amplitudes.
IFSTTAR has designed and experimentally validated a prototype
damper with a wider spectrum of action based on
Shape Memory Alloys (SMA). This was the culmination of
the European SMARTeR programme (1) (2006-2010) which
was led by the former LCPC. The core of the damper consists
of 8 thin SMA wires which dissipate the vibrational energy.
Certain Nickel-Titanium (NiTi) alloys exhibit what is known as
“superelastic” behaviour which means they can be deformed
to a considerable extent without
any residual deformation.
The material undergoes
a solid-solid phase
transformation between two
different crystallographic
structures.
The resulting dissipation of
energy provides NiTi with a very
high damping capability.
Conducting this design work also gave us
an opportunity of researching into the behaviour
of SMAs, NiTi in particular.
A patent has been filed as a result of this project. It is
currently being extended to the international level.
@ CONTACTS
lamine.dieng@ifsttar.fr
michael.peigney@ifsttar.fr
A diagram
of the damper.
81
(1) Shape Memory Alloys to Regulate Transient Responses in civil engineering.
Protection of children
Predicting abdominal injuries
In a car crash, rear seat passengers seem to be particularly
at risk of abdominal injury. The group with the
greatest exposure is children of between 6 and 10 years
of age who are sitting on a booster seat and wearing a
seat belt.
The abdominal Pressure
Twin Sensors next to a Q-series
child crash test dummy.
These injuries are still difficult to predict. Current crash
dummies are poorly (or not at all) fitted with sensors for this
anatomical region and do not provide us with a sufficiently
accurate evaluation of risk. This problem affects the P-series
child dummies that are currently specified by the regulations
for the protection of children and the certification of seats. To
fill this gap, the LBMC has been trying for a number of years
to design abdominal sensors in the framework of the European
CREST, CHILD and, more recently, CASPER projects.
The device that has been developed, known as the Abdominal
Pressure Twin Sensors (or APTS) consists of two soft bladders
filled with fluid which are fitted with pressure sensors and
installed in the abdomen of the dummy. It is able to detect
direct loads that are applied to the abdomen and estimate
their intensity from the pressure.
The APTS have shown their value during laboratory tests and
crash reconstructions during the CHILD and CASPER projects.
Recent developments have included improved sensors, and a
patent application has been filed. This system is arousing much
interest and may eventually be used for regulatory purposes or
in consumer tests such as EuroNCAP. Possible developments
under consideration include use in adult dummies or for other
transport modes.
@ CONTACT
philippe.beillas@ifsttar.fr
ANNUAL REPORT 2011 ifsttar.fr