Abstract: A constitutive relation to describe the pseudo-elastic deformation in shape memory alloys is presented in this paper. It is able to describe the deformation of polycry-stalline materials under triaxial stress state as well as of monocrystalline materials under one-dimensional condition. The total strain rate is supposed to be composed of elastic strain rate and transformation strain rate. The deformation behaviour of Cu-Zn-Sn alloy and Ti-Ni alloy is simulated by use of the proposed constitutive relation. T...