Análise termomecânica de molas helicoidais de seção retangular de ligas com memória de forma NI-TI obtidas por fundição de precisão.

Abstract

Rectangular cross section springs are generally used in applications with limited space, especially where total height is constrained. This type of spring stores more energy in a smaller space than circular wire springs of comparable dimensions, despite the non-uniform stress distribution. Thus, combining the higher energy storage capacity of this type of spring with the active and functional characteristics of shape memory alloys (SMA) has enabled an enhancement of this mechanical element's functionalities. The study of the behavior of this type of spring is crucial for predicting its mechanical performance, enabling its use in applications that demand compact designs and high energy storage capacity.In the literature, studies on SMA springs made from wire or filament are quite common, but there are few reports on SMA springs with rectangular sections. This work focused on the experimental mechanical behavior of springs made from shape memory alloys, which was made possible by the infrastructure of LaMMEA/UFCG. Classical material springs were commercially acquired, while prototypes were produced using the investment casting process. In this research, the behavior of rectangular section springs manufactured through investment casting was studied using two alloys: Ni-Ti and Ti-Ni-Cu. A castability study was conducted using computational simulations, and based on the results, the optimal runner system design for spring casting was selected. Finally, the springs underwent heat treatment and were characterized through tensile tests, tension and compression at constant temperatures, and DSC analysis.