A model of martensitic unelasticity accounting for the crystal symmetry of the material

An approach is presented to describe the mechanical behavior of the shape memory materials. On the one hand it uses the basic concepts of the structure-analytical theory proposed by V.A.Likhachev and V.G.Malinin which are the formulation of the constitutive equations of the phase transformation and martensitic unelasticity for micro regions and the orientation averaging of micro strains to obtain the macro strain. On the other hand the averaging procedure is arranged in a way to account for the crystal symmetry of the material. Results are presented of the computer simulation of pseudoelasticity, shape memory effect and active straining of a shape memory material with a thermoelastic martensitic transformation. These are stress-strain diagrams at various temperatures, temperature dependencies of the martensitic unelastic strain. All the results show good qualitative agreement with the experiments in which dislocation plasticity does not play a significant role.