8 \(\mathbf{\sigma}\left(\mathbf{u}\mathrm{,}\varphi\right)=g\left(\varphi\right)\frac{\partial\psi_{e}\left(\mathbf{\varepsilon}\right)}{\partial\mathbf{\varepsilon}}=g\left(\varphi\right)\mathbb{C:}\mathbf{\varepsilon}\mathbf{\ ,}\)