Finite Element Modeling of Shape Memory Alloy Composite Actuators: Theory and Experiment

The present paper proposes a non-linear finite element model for the time response of a novel shape memory alloy (SMA) actuator. The actuator has a plane beam configuration composed of a matrix material with SMA sheets or wires embedded in and/or bonded to the matrix part. The finite element model can be used to analyze both active and passive (with or without heating activation) responses of this kind of actuators. Due to large shear stresses and deformations, the model is developed based on a higher order shear deformation beam theory together with the von-Karman strain field. A one-dimensional constitutive equation with non-constant material functions together with sinusoidal phase transformation kinetics is used for the thermo-mechanical behavior of the SMA actuator. The constitutive and phase transformation kinetic equations make distinction between the stress-induced and temperature-induced martensite fractions. To evaluate the model, the fabrication of a prototype SMA composite actuator for conducting experiments is briefly described and the experimental work performed on the prototype actuator is presented. The test results are compared with the finite element numerical results. A good agreement between the finite element and experimental results corroborate the nonlinear finite element modeling approach.