TWSME of a NiTi strip in free bending conditions: experimental and theoretical approach
This paper deals with the two-way shape memory effect (TWSME) induced on a strip of a nearequiatomic NiTi alloy by means of the shape memory cycling training method. This procedure is based on the deformation in martensite state to reach the desired cold shape followed by cycling the temperature f...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Gruppo Italiano Frattura
2014-07-01
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| Series: | Fracture and Structural Integrity |
| Subjects: | |
| Online Access: | http://www.gruppofrattura.it/pdf/rivista/numero29/numero_29_art_8.pdf |
| Summary: | This paper deals with the two-way shape memory effect (TWSME) induced on a strip of a nearequiatomic
NiTi alloy by means of the shape memory cycling training method. This procedure is based on the
deformation in martensite state to reach the desired cold shape followed by cycling the temperature from above
Af to below Mf. To this end, the sample was thermally treated to memorise a bent shape, thermomechanical
trained as described and thermally cycled in unloaded conditions in order to study the stability of the induced
TWSME. Heating to Af was reached by a hot air stream flow whereas cooling to Mf was achieved through
natural convection. The evolution of the curvature with the increasing number of cycles was evaluated. The
thermomechanical behaviour of the strip undergoing uniform bending was simulated using a one-dimensional
phenomenological model based on stress and the temperature as external control variables. Both martensite and
austenite volume fractions were chosen as internal parameters and kinetic laws were used in order to describe
their evolution during phase transformations. The experimental findings are compared with the model
simulation and a numerical prediction based on the approach proposed in [25]. |
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| ISSN: | 1971-8993 1971-8993 |