Microstructures corresponding to curved austenite-martensite interfaces

Abstract

Let \Omega\subset\mathbb{R}^{2} denote a bounded Lipschitz domain and consider some portion \Gamma_{0} of \partial\Omega representing the austenite-twinned martensite interface which is not assumed to be a straight segment. We prove \underset{u\in\mathcal{W}(\Omega)}{inf}\int_{\Omega}\varphi(\nabla u(x,y))dxdy=0 for an elastic energy density \varphi:\mathbb{R}^{2}\rightarrow[0,\infty) such that \varphi(0,\pm1)=0. Here \mathcal{W}(\Omega) consist of all functions u from the Sobolev class W^{1,\infty}(\Omega) such that \left|u_{y}\right|=1 a.e. on \Omega together with u=0 on \Gamma_{0}. Moreover some minimizing sequences vanishing on the whole boundary \partial\Omega are constructed, that is, one can even take \Gamma_{0}=\partial\Omega. We also show that the existence or nonexistence of minimizers depends on the shape of the austenite-twinned martensite interface \Gamma_{0}.