Design methodology of the Ni50Ti50 shape memory alloy beam actuator: Heat treatment, training and numerical simulation

Abstract

Shape memory alloy (SMA) beam actuators are widely used in morphing structures, which leads to a surgent demand for a comprehensive design method. Previous methods have not considered the heat treatment and the evolution of actuation performance during training. In this study, an in-depth investigation was conducted into the Ni50Ti50 (at%) SMA beam actuator from the perspective of heat treatment, training, numerical simulation for developing a comprehensive and novel design methodology. The proper heat treatment conditions that result in the relatively high actuation performance for the Ni50Ti50 SMA beam were determined. The dependence of the thermomechanical behavior evolution on the training load was established. Moreover, a numerical analysis method for the SMA beam actuator based on a 3-D constitutive model with tension-compression asymmetry considered was detailed, followed by the calibration of material parameters. A forward design method for the SMA beam actuator was proposed with the shape and actuation performance evolution during training under various training loads fully considered in the design process. The proposed design method was applied for a design case and the accuracy of the design results demonstrated its feasibility.