Description of Deformation of Shape-Memory Materials by Thermomechanical and Alternating Loads

We develop a phenomenological model of irreversible deformation of dislocation nature for shape-memory materials based on iron. The abnormal decrease in the yield stress in the vicinity of the temperature of onset of the direct martensitic transformation and residual microstresses depending on the history of force and temperature loads are taken into account. The model is applied to the results of thermomechanical and alternating cyclic tests. The loading surface is constructed and its transformations are described. The numerical results are compared with the experimental data for a shape-memory alloy based on iron with 9% Cr, 5% Ni, 14% Mn, and 6% Si. It is shown that the proposed model is applicable to the description of the deformation behavior of the material. The obtained results can be used for the description of the thermomechanical behavior of elements of shape-memory mechanisms and structures.