Desenvolvimento de um equipamento para caracterização térmica de atuadores de ligas com memória de forma usando o efeito termoelétrico.

Abstract

This work presents a development of equipment for thermal analysis which used thermoelectrometry technique. The equipment is directed to the characterization of transformation temperatures and thermal hysteresis of shape memory alloys (SMA). Therefore, it was designed and assembled an test platform for submitting a SMA sample to a controlled temperature program, also hold real-time measurements of electrical resistance or voltage signals in the SMA sample. This platform has as main component a thermoelectric tablet that works by Peltier effect to produce cooling and heating of the SMA sample. The device allow make successive thermal cycles between minimum and maximum temperatures in the temperature range from - 50 ºC to 150 ºC, with controlled rate cooling and heating through the implementation of a fuzzy controller. To validate the developed system some tests were performed using Ni-Ti SMA samples. In addition, the electrical resistivity of commercial copper was also determined with the apparatus. The obtained results of Resistance (Ω) vs. Temperature (ºC) characterization curves are in accord with literature. From a practical standpoint, the work led to experimental characterization equipment for the fundamental study of shape memory alloys, which will be constantly used in the research developed by the Multidisciplinary Laboratory of Active Materials and Structures (LaMMEA) of UAEM / CCT / UFCG.