Simulink-based Thermo-Electro-Mechanical Model of Shape Memory Alloy Wires for Actuator Applications

Accurate, physics-based modelling of shape memory alloy (SMA) wires enables efficient actuator and sensor design. This study presents a modular Simulink implementation of a thermo–electro–mechanical model that couples Joule heating, one-dimensional heat conduction, and stress-dependent phase transformation kinetics. The model captures temperature-dependent resistivity, includes latent heat for transformation enthalpy, and accounts for convective boundary losses. Phase evolution follows a kinetic law parameterised by transformation temperatures and a Clausius–Clapeyron–type coefficient that links stress and temperature.

Electrical excitation generates Joule heating, which raises the temperature of the wire. The resulting feedback between temperature, resistivity, and phase fraction reproduces the hysteretic thermo-mechanical response typical of SMA behaviour. The model integrates modular Simulink blocks with stiff ordinary differential equation solvers to maintain numerical stability. Key outputs include heating–cooling hysteresis loops, transformation-rate curves, steady-state temperature distributions, and parametric performance maps.

Assumptions are defined: a one-dimensional thermal model, uniform axial stress, and negligible microstructural heterogeneity. Material parameters, such as transformation temperatures, thermal conductivity, specific heat, resistivity coefficients, and latent heat, are user-defined for various SMA compositions.

The proposed Simulink model provides a reproducible, physics-based approach for characterisation and preliminary design of SMA wire actuators. Hence, the model can facilitate researchers and engineers in studying coupled thermal-mechanical effects, exploring design parameters, and predicting performance prior to prototyping.