A coupled model between hydrogen diffusion and mechanical behavior of superelastic NiTi alloys

The undesirable effects of hydrogen show significant alterations to the thermomechanical behavior of superelastic NiTi shape memory alloys. Through experimental results, the presence of hydrogen induces a delay of forward transformation. Added to that, hydrogen-induced expansion is clearly noticed....

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Bibliographic Details
Published inSmart materials and structures Vol. 26; no. 7; pp. 75001 - 75011
Main Authors Elkhal Letaief, W, Hassine, T, Gamaoun, F
Format Journal Article
LanguageEnglish
Published IOP Publishing 01.07.2017
Subjects
constitutive modeling
experimental tests
finite element
hydrogen diffusion
NiTi
shape memory alloy
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Summary:The undesirable effects of hydrogen show significant alterations to the thermomechanical behavior of superelastic NiTi shape memory alloys. Through experimental results, the presence of hydrogen induces a delay of forward transformation. Added to that, hydrogen-induced expansion is clearly noticed. We also remark a loss of superelasticity. These effects occur according to the hydrogen absorption by the NiTi alloy. The aim of this paper is to develop a coupled diffusion-mechanical model of shape memory alloys, which regards the aforesaid effects of hydrogen on the thermomechanical behavior and the transformation mechanism of NiTi alloys. The model is derived from the relationship between the chemical potential of hydrogen and the thermodynamics laws. Furthermore, we introduce a special transformation hardening function that predicts stress-strain behavior well during the transformation plateau. The model is implemented in ABAQUS finite element analysis software through the UMAT and UMATHT subroutines. The simulation results present good concordance with the experiments.
Bibliography:SMS-104714.R2
ISSN:0964-1726
1361-665X
DOI:10.1088/1361-665X/aa721b