2010 年 35 巻 2 号 p. 359-363
The phase transformation behavior of polycrystalline shape memory alloys is investigated by a constitutive model under multi-axial stress states of tension and shear. The constitutive model used here was developed by the authors to describe the accommodation mechanism acting on the phase transformation phenomenon. The transformation occurs in microscopic transformation systems of crystals and is calculated by the constitutive model. The transformation stress is introduced here as an indicator to describe the macroscopic transformation start. Transformation stresses are obtained from calculated stress-strain curves for various loading paths. The interaction surface of macroscopic transformation stresses obtained is revealed to be very similar to the Mises yield surface in the stress space. Discussions are also made on the relation between the equivalent stress and the equivalent transformation strain of Mises type.