Modeling tensile-compressive asymmetry for superelastic shape memory alloys

In this article, the Zaki-Moumni (ZM) model for shape memory alloys is extended to account for tensile-compressive asymmetry over a wide temperature range. To this avail, a mathematical framework recently developed by Raniecki and Mroz is utilized to define new yield functions that are sign-sensitive. With respect to the original ZM model, the modifications are essentially made to the expressions of the Helmholtz free energy and of the internal constraints. The model is shown to properly simulate the asymmetric behavior of shape memory alloys both for martensite orientation and pseudoelasticity.