Energy-based analysis of temperature oscillation at the shakedown state in shape memory alloys

This paper documents an energy-based analysis of temperature oscillation during cyclic stress-induced phase transformation in shape memory alloys (SMAs). The conversion of total hysteresis work into dissipated heat and stored energy in SMAs is discussed, and the temperature oscillation at the shakedown state in cyclically loaded SMAs is modeled. To validate the theoretical model, both strain and stress-controlled tensile tests on pseudoelastic NiTi wires are performed under cyclic loading and an infrared camera is used to record the surface temperature of the wire. The results show that depending of the loading type, strain or stress-controlled loading, the amplitude of temperature oscillation during cyclic stress-induced phase transformation evolves differently with the frequency: The amplitude of the temperature oscillation under strain-controlled loading gradually reaches a saturated value independent of the frequency; however, for stress-controlled loading, the saturated temperature amplitude is frequency-dependent since it reduces significantly if the frequency is increased. (authors)