The drawing or rolling process endows polycrystal shape memory alloy with a crystallographic texture, which can result in macroscopic anisotropy. The main purpose of this work is to develop a constitutive model to predict the thermomechanical behavior of shape memory alloy sheets, which accounts for the crystallographic texture. The total macroscopic strain is decomposed into elastic strain and macro-transformation strain under isothermal condition. Considering the transformation strain in local grains and the orientation distribution function of crystallographic texture, the macro-transformation strain and the effective elastic modulus of textured polycrystal shape memory alloy are developed by using tensor expressions. The kinetic equation is established to calculate the volume fraction of the martensite transformation under given stress. Furthermore, the Hill's quadratic model is developed for anisotropic transformation hardening of textured SMA sheets. All the calculation results are in good agreement with experimental data, which show that the present model can accurately describe the macro-anisotropic behaviors of textured shape memory alloy sheets.
A large field-induced strain of magnetic shape memory alloy is developed by the martensite variant reorientation.It is widely recognized that the martensite reorientation in a magnetic shape memory alloy(MSMA) can develop if the magnetic field is large enough.However,it has been shown in the literature that the magnetization rotation may block variant reorientation via energy minimization approach.In this paper,based on a micromechanical model associated with the thermodynamic theory,authors show that there are some limits for the martensite reorientation,which is hindered by the magnetization rotation.Some useful conclusions are obtained.
