Given the following strain state $($given in $\%$ strain$),$

$=\{[{}_z],[{}_y],[{}_z],[{}_{yz}],[{}_{xz}],[{}_{xy}]\}=\{[0\mathrm{.}01375],[0\mathrm{.}04625],[-0\mathrm{.}035],[0\mathrm{.}1625],[0\mathrm{.}0325],[-0\mathrm{.}0975]\}\%$

compute the state of stress $($in matrix form$)$ and the numerical value of the elastic strain energy per unit volume in $\frac{J}{m^3},U,$ in an isotropic steel. $E=200$GPa and

$u=0\mathrm{.}3.$