Mathematical Model of SMA Spring Actuator in a Miniature Flexible Tube Robot

Shape memory alloy (SMA) has the potential to be used as an actuator in miniaturized and flexible models. In this paper, an existing theoretical model is used to predict the force capabilities of an SMA spring in challenging applications like a miniature flexible tube robot for tumor irradiation applications. A heat transfer model based on Joule heating is used to predict the temperature variations with time. A Brinson model-based phase kinetics together with constitutive model predicts the variation of martensite fraction and recovery force with temperature. The results help to estimate the force capabilities of an SMA spring when used as an actuator.