Two-way shape memory effect of a Ti rich NiTi alloy: experimental measurements andnumerical simulations

Abstract

In this paper the two-way shape memory effect (TWSME) of a Ni–51 at.% Tialloy is investigated and a numerical model is developed, which allows real timesimulations of its hysteretic behaviour strain versus temperature. The two-wayshape memory effect (TWSME) was induced through a proper thermo-mechanicaltraining, carried out at an increasing number of training cycles and for two values oftraining deformation. The TWSME was measured under different appliedstresses and the hysteretic behaviour in the strain–temperature response wasrecorded. In order to evaluate the thermal stability of the hysteresis loops thematerial was subjected to many cycles, by repeated heating and cooling, betweenAf (austenite finishtemperature) and Mf (martensite finish temperature). The numerical method isbased on a phenomenological approach and was developed in aMatlab® function, which calculates the model parameters from a set of experimental data, and aSimulink® model, which is efficient enough for use in real time applications. The accuracy of theproposed model was analysed through systematic comparisons between experimentalmeasurements and numerical predictions.