R-phase shape memory alloy helical spring based actuators: Modeling and experiments

Abstract The main goal of this paper is to propose some analytical or pseudo-analytical tools facilitating the study and modeling of SMA helical spring-based actuators. Particular attention is paid to R -phase SMA helical spring-based actuators ( i.e. , springs made in NiTi and concerned by R -phase transformation phenomena). First, simplified models ( i.e., based on beam theory framework) of R -phase SMA helical springs taking into account detwinning and assisted two-way memory effect are proposed and validated. Then, these models are used to determine the thermo-mechanical behavior of a linear bias-spring actuator. An actuator is built and used to validate the proposed models.