(eng): A sharp-interface model describing static and quasi-static equilibrium configurations of shape memory alloys by means of interfacial polyconvex energy density is computationally tested. Elastic properties of variants of martensite and the austenite are described by polyconvex energy density functions. In addition, energy stored in martensite–martensite and austenite–martensite interfaces is measured by an interface-polyconvex function. It is assumed that transformations between material variants are accompanied by energy dissipation, which, in our case, is positively one-homogeneous giving rise to a rate-independent model