Consider an orthotropic material with the stiffness matrix given by

$[C]=\left[\begin{array}{cccccc}-0\mathrm{.}67308& -1\mathrm{.}8269& -1\mathrm{.}0577& 0& 0& 0\\ -1\mathrm{.}8269& -0\mathrm{.}67308& -1\mathrm{.}4423& 0& 0& 0\\ -1\mathrm{.}0577& -1\mathrm{.}4423& 0\mathrm{.}48077& 0& 0& 0\\ 0& 0& 0& 4& 0& 0\\ 0& 0& 0& 0& 2& 0\\ 0& 0& 0& 0& 0& 1\mathrm{.}5\end{array}\right]$GPa

Find:

The stresses in the principal directions of symmetry if the strains in the principal directions of symmetry at a point in the material are ${}_1=1\frac{m}{m},{}_2=3\frac{m}{m},{}_3=2\frac{m}{m}$;${}_{23}=0,{}_{31}=5\frac{m}{?}m,{}_{12}=6\frac{m}{m}$

The compliance matrix $[$S$]$

The engineering constants $E_1,E_2,E_3,v_{12},v_{23},v_{31},G_{12},G_{23},G_{31}$

The strain energy per unit volume at the point where strains are given in part $(1.)$