\(E_{\mathcal{l}}\left(\mathbf{\varepsilon}^{e}\mathrm{,}\mathbf{\varepsilon}^{p}\mathrm{,}\alpha\right)=\int_{\Omega}{\left[\psi_{e}\left(\mathbf{\varepsilon}^{e}\right)+\psi_{p}\left(\alpha\right)\right]d\mathbf{x}}\ ,\)