Effect of Variation in Applied Force on Transformation Temperatures of NiTinol SMAs

Shape Memory Alloys (SMA) are promising materials for actuation in space applications, because of the relatively large deformations and forces that they offer. However, their complex behaviour and interaction of several physical domains (Electrical, Thermal and Mechanical), the study of SMA behaviour is a challenging field. Phase transformation temperature is one of the most important parameters for the shape memory alloys (SMAs). In this present work, a novel method of determining transformation temperatures is carried out which uses dead weight. The SMA NiTinol wire was applied with force and maintained constant throughout the experiment and at the same time it was heated up slowly until a temperature of approximately 80°C with direct current. The direct current was then slowly decreased to cool down the temperature of the NiTinol wire. All the phase transformation temperatures for NiTinol SMA wire were obtained. A variation in transformation temperatures are recorded with variation in applied force, which is an important aspect calls for attention before using the material in any application. In the present work, it has been investigated and reported in detail.