Virtual Instrumentation for Study of Shape Memory Alloys Strip while Bending


In this paper, using LabVIEW graphical pro-gramming environment and the portable reconfigurable input/output (RIO) device from National Instruments (myRIO-1900), the concept of virtual instrumentation is implemented. Thus, it is created a hardware and software system that is used to study the nickel and titanium shape memory alloy (NiTi SMA) strip during bending under the influence of electric current. The SMA strip is caught in cantilever mode (fixed at one end only). For this study, the following quantities are measured: the deformation of the strip (using a created electronic transducer around an oper-ational amplifier and a piezoelectric effect sensor), the volt-age applied to its ends and the current flowing through it (with LEM transducers). The evolution of the electrical re-sistance as well as the bending of the SMA band at different values of the electric current, during and due to the heating process is reported using this system. The values of the measured quantities are presented in graphical and numeri-cal form. Thus, the evolution on time intervals of the order of seconds can be followed with precision with the help of horizontal and vertical cursors, respectively. Amplitude values can also be accurately determined. The results ob-tained with the proposed system are useful in practical ap-plications of cantilever SMA strip for development of sim-ple, more compact and reliable actuators or sensors. images