Actuator and/or Sensors Integration by Additive Manufacturing for Intelligent Mechanical Applications

Abstract

Shape memory alloys (SMA) are a group of metallic alloys that have attracted much interest as a functional material in a myriad of engineering fields, as active, adaptive, or intelligent structures. These binary compounds present unique properties besides shape memory effect (SME), super elasticity (SE). Among SMA, the NiTi (Nitinol) is the most relevant intermetallic compound due to its functional and excellent mechanical properties [1-2]. The unforeseen functional properties of SMA are due to a reversible martensitic transformation between a stable high-temperature austenitic phase (B2) and low-temperature martensitic phase (B19’). The martensitic transformation can occur directly (B2 ⬌B19’) or via R-phase [3]. The super elasticity results from the stress-induced martensitic transformation (SIM) between austenite and martensite[4,5]. Moreover, the shape memory effect is also caused by thermal-induced martensite transformation (TIM) [3]. This behavior lets to their application as actuator and/or sensor, because their structures may detect the mechanical stresses and thermal changes around them and reply almost instantly to the external variation [1-7].