Modeling bending response of shape memory alloy wires/beams under superelastic conditions - A two species thermodynamic Preisach approach

Abstract

In this paper, a model to capture the pure bending response of shape memory alloys (SMA) beams/wires under superelastic conditions is constructed by combining thermodynamics principles along with preisach models. The model is formulated directly using experimentally measurable quantities “Bending Moment and Curvature” rather than evaluating the same from stress resultants by integration as commonly followed in literature. Following Doraiswamy et al. (2011), the key idea here is in separating the elastic and the dissipative part of the hysteritic response with a Gibbs potential based formulation and thermodynamic principles. The preisach model is then employed in capturing the dissipative part of the entire thermoelastic response. Such an approach can simultaneously include both thermal and mechanical loading in the same framework andone can easily simulate complex temperature dependent superleastic responses. The model results are compared with experiments performed on SMA wires/beams at dierenttemperatures as reported in the literature for NiTi and CuZnAl material systems.