Abstract
With increasing number of loading cycles, stress-strain hysteresis loops of pseudoelasticity of a shape memory alloy vary continuously in experiments. To account for such characteristic variance observed during phase transformations, the effect of residual martensite is taken into account in a thermomechanical model based on the phase interaction energy function which we proposed in our previous studies. A functional form of volume fraction of the residual martensite which monotonically increases with increasing loading cycle has been determined using experimental stress-strain loops. It is shown that a simple function of the volume fraction of the residual martensite may model complicated behavior of the transformations in the cyclic loading.