Braga Rafael, Rodrigues Patrícia Freitas, Cordeiro Hélder, Carreira Pedro, Vieira Maria Teresa
University of Coimbra, Department of Mechanical Engineering, CEMMPRE, R. Luís Reis Santos, 3030-790 Coimbra, Portugal.
Moldes RP, R. José Alves Júnior, 411, 2430-076 Marinha Grande, Portugal.
Materials (Basel). 2022 Jul 8;15(14):4787. doi: 10.3390/ma15144787.
Actuators using Shape Memory Alloy (SMA) springs could operate in different mechanical systems requiring geometric flexibility and high performance. The aim of the present study is to highlight the potential of these actuators, using their dimensional variations resulting from the phase transformations of NiTi springs (SMA) to make the movements of the system's mobile components reversible. This reversibility is due to thermal-induced martensitic transformation of NiTi springs. The transformation promotes the extended and retracted of the springs as the phase changing (martensite-austenite) creates movement in part of the system. Therefore, the phase transition temperatures of NiTi, evaluated by differential scanning calorimetry (DSC), are required to control the dimensional variation of the spring. The influence of the number of springs in the system, as well as how impacts on the reaction time were evaluated. The different numbers of springs (two, four, and six) and the interspaces between them made it possible to control the time and the final angle attained in the mobile part of the system. Mechanical resistance, maximum angle, and the system's reaction time using different NiTi springs highlight the role of the actuators. Fused Deposition Modelling (FDM)/Material Extrusion (MEX) or Selective Laser Sintering (SLS) was selected for shaping the composite matrix system. A new prototype was designed and developed to conduct tests that established the relationship between the recoverable deformation of the matrix suitable for the application as well as the number and distribution of the actuators.
使用形状记忆合金（SMA）弹簧的致动器可在需要几何灵活性和高性能的不同机械系统中运行。本研究的目的是突出这些致动器的潜力，利用镍钛弹簧（SMA）相变引起的尺寸变化，使系统移动部件的运动可逆。这种可逆性是由于镍钛弹簧的热致马氏体相变。随着相变（马氏体 - 奥氏体）在系统的一部分中产生运动，这种转变促使弹簧伸长和收缩。因此，需要通过差示扫描量热法（DSC）评估镍钛的相变温度，以控制弹簧的尺寸变化。评估了系统中弹簧数量的影响以及对反应时间的影响。不同数量的弹簧（两个、四个和六个）及其之间的间隙使得控制系统移动部分达到的时间和最终角度成为可能。使用不同镍钛弹簧时的机械阻力、最大角度和系统反应时间突出了致动器的作用。选择熔融沉积建模（FDM）/材料挤出（MEX）或选择性激光烧结（SLS）来成型复合基体系统。设计并开发了一个新的原型，以进行测试，确定适合该应用的基体可恢复变形与致动器数量和分布之间的关系。
