(structures] Given the stress function, $\Omega(x, y)$, as (A and B are constants)
$$
\Omega(x, y)=A x^{2} y^{4}+B x^{4} y^{2}
$$
find the stresses, $\sigma_{x}$ and $\sigma_{y}$, where
$$
\sigma_{x}=\frac{\partial^{2} \Omega}{\partial y^{2}} \text { and } \sigma_{y}=\frac{\partial^{2} \Omega}{\partial x^{2}}
$$