Comments to the paper "Differential and integrated form consistency in 1-D phenomenological models for shape memory alloy constitutive behavior" by V.R. Buravalla and A. Khandelwal [Int. J. Solids and Struct. 44 (2007) 4369-4381]

Several views on differential and integrated form consistency in 1-D phenomenological models for shape memory alloy constitutive behavior, are presented. The integrated form of the behavior, known as as the Brinson SMA model, has been extensively tested and remains correct, as Buravalla and Khandelwal, revealing the extrapolated differential form that violates the compatibility condition for the stress. A different expression for the function Xs need to be assumed to satisfy the compatibility condition, as suggested by Buravalla and Khandelwal. It has also been observed that the separation of the martensite fraction into stress-induced and temperature-induced forms is essential to the success of the Brinson model for the entire phase diagram.