Caracterização termomecânica de atuadores com memória de forma

Abstract

The shape memory alloys have been used in such different work areas, in different functions and in different shapes. For their application, it is extremely important to peform a characterization of them. Based on these facts, it has been done a characterization in shape memory alloys (SMA) samples, in shape of micro-springs, in order to extract the parameters of the SMAs supported in different thermoelectric excitation. In addition to the theoretical background for the SMA, a conceptual notion about the instruments used to carry out this characterization was set. The shape memory effect was imposed in the samples, in three different levels of electric current, and in six stages of lenght of 50 % to 300 % were presented. It has been found that the applied elongation is a variable of several forms in the characteristics of the spring. The higher the intensity of the sample, the higher the residual strength, the lower the temperature with high excitation, but there is a natural convection effect with the means. It was added as a maximum force influence of 351 mA, while a force measurement of 2.4 N was 22.5 mm, and a temperature of 107.9 °C under the deformation of 13.5 mm. Note that there is a greater capacity of 150 %, in which a greater range of force, no matter which of the tree currents employed.