Caracterização termomecânica de atuadores belleville de ligas com memória de forma.

Abstract

In current stage of scientific and technological development in the area of smart materiais, researches around the world have originated advances which are able to allow their effective use as sensors and actuators, especially in case of Shape Memory Alloys (SMA). This interest comes from the fact of these SMA being metallic materiais able to recover high amount of residual strain (at about 5% in uniaxial tensile) just by simple heating. In this regard, this study had as main aim to manufacture and evaluate the bifunctional thermomechanical behavior of SMA Belleville actuators (SMACON) from the Ni-Ti alloy system. These elements manufactured with local technology are appropriated for generation of forces in bolted connections through Shape Memory Effect and Superelasticity. For this purpose, there were selected SMA compositions of 55.3Ni-44,7Ti (wt%) and 14Nb-48Ni-38Ti (wt%) which have superelastic properties at room temperature (~ 27 ° C). The method used to carry out the measurement of generated force of SMACON versus time and temperature, involved deformation at cryogenic temperatures, below - 50 ° C, and natural heating by the heat exchange with local environment. The obtained results showed it is possible to use the bifunctionality of the SMACON for static applications (bolted joint) and dynamic (energy dissipation elements), keeping in mind that the generated forces were in the order of 2.5 kN and superelasticity of 40% in relation to height of the actuator.