FEM-Analysis of the One-Dimensional Coupled Thermomechanical Problem of TiNi SMA

Abstract
In problem solving regarding SMA materials thermomechanical coupling has to be taken into account due to latent heat of martensitic transformation and heat production resulting from the SMA material internal dissipation processes. Recently there has been developed thermodynamic three dimensional R_L model of SMA behaviour in pseudoelastic range taking into account relevant transformation kinetic laws of thermoelastic martensitic transformations. In the present paper finite element code with implemented R_L model constitutive equations has been applied to one-dimensional model of SMA wire sample placed in testing machine. The heat exchange conditions in the form of heat conduction along the wire and heat convection into the surrounding air have been considered. The performed coupled thermomechanical calculations allowed for quantitative évaluation of the influence of the strain rate on the stress-strain curves. The obtained numerical results have been compared with available in the literature experimental data to show sufficiently good quantitative agreement.