Implementation strategy for the dual transformation region in the Brinson SMA constitutive model

Abstract

The transformation kinetics formulation is the principal factor underlying the constitutive model of shape memory alloys (SMAs). Therefore, the transformation kinetics formulation, which is applicable to any status of stress and temperature, is essential for predicting the material behavior of SMAs. In this work we show that the transformation kinetics of the original Brinson model, which is the most widely used one-dimensional model, has shortcomings in the case where temperature decreases at low temperature (T < M-s). In addition, we propose a modified transformation kinetics formula that can be used for dual transformation conditions. The martensite transformation kinetics is modified so that the transformation from austenite into temperature-induced martensite, due to the decrease in temperature, is coupled with a transformation from austenite or temperature- induced martensite into stress-induced martensite, due to the increase in stress. Through this modification, the suggested formulation can properly describe the behavior of martensite fractions in the dual transformation region.