Tube $\left(1\right)$ has an outer diameter of $\mathrm{D}=30 \mathrm{mm}$ and an inner diameter of $\mathrm{d}=22 \mathrm{mm}$. The elastic modulus of the aluminum is $70 \mathrm{GPa}$. The brass core $\left(2\right)$ has a diameter of $\mathrm{D}=22 \mathrm{mm}$ and an elastic modulus of $105 \mathrm{GPa}$.

Compute the normal stresses in tube $\left(1\right)$ and core $\left(2\right)$.