Modeling of functional fatigue of SMA-based actuators under thermomechanical loading and Joule heating

A new constitutive modeling is proposed to simulate the cyclic thermomechanical behavior of SMA-based actuators activated by Joule heating. It uses a weak coupling method to contemplate together the impact of different phenomena highlighted during experimental tests: thermal exchange through the SMA component and with the surrounding, heating by electric current (Joule effect), microstructural evolution leading to performance degradation (functional fatigue), and thermomechanical coupling. After experimental characterization and model implementation, simulation results are compared with experimental tests to validate the strategy and demonstrate its utility for designing SMA-based actuators.