ELFT HÍRADÓ

[Károlyi György <karolyi AT tas.me.bme.hu>]

MEGHÍVÓ 

a BME Tartószerkezetek Mechanikája Tanszék 
által szervezett szemináriumra 

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Corneliu Cismasiu 
(Universidade Nova de Lisboa) 

Shape Memory Alloys in Structural Vibration Control 

2009. július 1. szerda, 10.00 óra

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Az előadás helye:
BME Tartószerkezetek Mechanikája Tanszék
K épület, magasföldszint 35., könyvtár

Az előadás tartalma:  
The unique superelastic behaviour exhibited by shape memory alloys (SMAs)
allows the material to recover after withstanding large deformations.
This recovery takes place without any residual strains, while dissipating
a considerable amount of energy, making the SMAs particularly suitable
for applications in vibration control devices. The dynamic behaviour of
vibration control devices built up of austenitic superelastic wires is
investigated using two different constitutive models. The first model,
although being able to describe the response of the material to complex
uniaxial loading histories, is temperature and rate independent. The
second, couples the mechanical and kinetic laws of the material with a
balance equation considering the thermal effects. The energy dissipation
and re-centring capabilities, important features of these devices, are
clearly illustrated by the numerical tests. A novel semi-active vibration
control device based on superelastic shape memory alloy wires is proposed
next. Although it mainly behaves as a passive control system, its
controllable properties enhance the energy dissipation and re-centring
capabilities, with no need for external energy input into the system.
It is built up of two sets of superelastic austenitic wires, working in
phase opposition. A special designed restraining system can either lock
or set free the displacement of the wires at the supports, preventing the
wires from failure while guaranteeing a minimal threshold to their strain
level. A detailed description of the proposed semi-active vibration
control device is given and numerical simulations used to confirm its
efficiency under harmonic or seismic excitations.

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