Functional Characterization of NiTi Shape Memory Elements for Smart Micro-Actuation

Shape Memory Alloys (SMAs) are smart and functional materials, which are considered good candidates for the activation of devices for the automotive, aerospace, biomedical and mechanical systems, thanks to the shape memory effect. In this work, a study on the mechanical response of NiTi SMA snake like elements has been proposed. The production route of these elements from thin sheets, was given by laser machining followed by chemical etching. The micro-elements were characterized by means of calorimetric analysis for the definition of the theoretical operating temperatures and by means of thermo-mechanical testing for the evaluation of their functional performances. Mechanical tests has been carried out to assess the tensile behavior of martensite and austenite separately, and to evaluate the thermal hysteresis under different constant loads. Moreover, Finite Element Modeling (FEM) has been also accomplished to study the numerical evaluation of the stress field that origins by the application of the different loads in both the martensitic and austenitic phases.