Thermomechanical couplings in shape memory alloy materials

In this work we address several theoretical and computational issues which are related to the thermomechanical modeling of shape memory alloy materials. More specifically, in this paper we revisit a non-isothermal version of the theory of large deformation generalized plasticity which is suitable for describing the multiple and complex mechanisms occurring in these materials during phase transformations. We also discuss the computational implementation of a generalized plasticity based constitutive model and we demonstrate the ability of the theory in simulating the basic patterns of the experimentally observed behavior by a set of representative numerical examples

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

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 RL 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 RL 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