Análise numérica e experimental de um anel superelástico de liga com memória de forma de ni-ti

Abstract

In this work are carried out numerical and experimental analyzes of a superelastic ring manufactured from a plate of shape memory alloy (SMA) of Ni-Ti. This ring was dimensioned according to DIN 471, which is used for external rings to be applied on shafts. For practical application, the ring was dimensioned for a shaft of nominal diameter of 10 mm. The other dimensions of the ring are: internal diameter 9.3 mm when free from deformation, thickness 1 mm and internal diameter of 9.6 mm when installed on shaft. The aim of this research is to perform the experimental characterization of the SMA superelastic ring and also propose the representation of this behavior by numerical simulations using the Finite Element Method (FEM) in ANSYS ™ Mechanical (Workbench) 15.0 software. In these simulations the SOLID186 element was used to model the ring because it supports the constitutive model used. By conducting the experimental tests it was possible to obtain the force-displacement curves that express the thermo-mechanical behavior of the actuator. These results were necessary to promote the calibration and validation of the numerical simulations. The phase transformations (austenite-martensite) that occurred during the simulations were demonstrated in a graph by calculating the martensite and austenite fractions as a function of the analysis time. Finally, to verify the functionality of the designed SMA actuator, a comparison between the deformation capacity for the same force of this ring and a conventional steel ring was performed. The superelastic ring demonstrated its great deformation capacity in the aperture without presenting residual deformations at the end of loading due to its pseudoelastic effect.