A physical model of polycrystalline Ni-Ti shape memory materials

This paper derives a physical model for the polycrystalline shape memory alloys (SMAs) on the micromechanical basis. For the given materials, the model provides the link between the transformation behavior at the crystal-level and the details of the scalar behavior as stress-strain hysteresis loop and shape memory effect at the macroscopic level. The developed model has been applied to simulate the tension test of Ni-Ti alloy wire and the tension, compression and thin-walled tubular torsion test of Ni-Ti alloy. It is shown that the developed viscoplastic model can faithfully capture the key characteristic of observed hysteresis loop of shape memory alloys, and at the same time retains computational efficiency.