Study of the stability of the NiTi wire applied to thermomechanical actuators

Shape memory alloys (SMA) have been the subject of several studies due to their excellent physical and mechanical properties. For this reason, a wire SMA is used in various applications as thermomechanical actuators that are subject to repeated thermal cycling in a range of temperatures and variable loads. The mechanical stability is a fundamental behavior that need to be understood to project well accurate actuators. Thus, the total recoverable strain must be constant under certain external conditions. In this research, an apparatus was built to monitor the recoverable strain in Ni-Ti SMA wire with differentiated thermomechanical training during prolonged thermal cycles under constant loads. Experimental results have shown that the recoverable strain decreases with cycling. In addition, an acceptable stabilization can be found for a specific condition of thermomechanical training and constant load.