Experimental Study on Shape Memory Alloy Displacement Transducer

Obtaining displacement responses of buildings under earthquake is important for structural damage identification in many cases. However, the sensors that measuring displacement is few. The focus of this paper is to develop a novel displacement transducer by using the strain-sensing property of austenitic shape memory alloy (SMA). This transducer can be installed on buildings for long term measurement due to the excellent ability of SMA resisting fatigue and corrosion. Another advantage of this transducer is that it can be combined with SMA damper to develop integrated SMA device with double functions of energy dissipation and displacement measurement. Large numbers of tests are carried out to measure the strain sensing property of an austenitic nitinol SMA wire, together with the basic performance characteristics, like sensitivity, linearity, hysteresis, repeatability and accuracy. Finally, this SMA displacement transducer is installed into the first story of a structural model and shaking table tests are carried out. The interstory drift at the first floor is measured by the SMA displacement transducer and is compared with the measurement results of LVDTs. All the experimental results demonstrate that SMA is a good candidate for developing displacement transducer.