| Numéro |
J. Phys. IV France
Volume 115, June 2004
|
|
|---|---|---|
| Page(s) | 185 - 194 | |
| DOI | https://doi.org/10.1051/jp4:2004115023 | |
J. Phys. IV France 115 (2004) 185
DOI: 10.1051/jp4:2004115023
Experimental study of torsion behaviour of NiTi alloy
P. Olier1, Ph. Matheron2 and J. Sicre31 Department of Elaboration and Control of Structure, Atomic Energy Commission (CEA), Saclay, France; CEA/DRT/LIST/DECS/SE2M, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
2 Department of Thermal Mechanics, Atomic Energy Commission (CEA), Saclay, France; CEA/DEN/DMT/SEMT/SRSI, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
3 Department of Spatial Technics, CNES/DTS/AE/MTE/ME, CNES Toulouse, 18 Av. Édouard Belin, 31401 Toulouse Cedex 4, France
Abstract
The goal of this paper is to have a better understanding
of the parameters which have an influence on torsional response
of NiTi shape memory alloys (SMAs). The SMA investigated in this
study was a titanium rich NiTi characterized by high transformation
temperature (A
of ~ 95 °C in fully annealed
conditions). Resulting from post-forming annealing, two metallurgical
conditions were achieved : restored conditions (470 °C-1 h) and
recrystallised conditions (600 °C-1 h). The phase transformation
temperatures and heat of transformation were measured for both conditions
by differential scanning calorimetry.
A first set of torsional tests were conducted in isothermal conditions
for three different mechanical loading paths. The torque against
the angular displacement was measured for each tested temperature.
As a comparison, isothermal stress-strain curves obtained in
tension and compression were reported which showing the influence
of the solicitation mode on mechanical parameters (shear and
young moduli, yield strength, critical strain and stress).
The second set of tests is designed to measure the amplitude
of shape memory effect and the recovery torque during heating.
Thermomechanical experiments include the torsion response for
thermal cycles under constant applied torque and for specimens
deformed in martensitic phase and heated above A
while their
displacement was kept constant. The thermo-mechanical cycles
were repeated at least three times for each specimen and for
one of them the cycling effect (up to 50 cycles) was investigated.
We found that the highest recovery torque and the largest level
of strain recovery were obtained for restored conditions.
© EDP Sciences 2004