PROBLEM $3.$

The rods AF and CE in the figure are made of Ti$-6$Al$-4$V $($Ti$-64)$ titanium material, with a crosssectional area of $200m{m}^2$ and a modulus of elasticity of $110$ GPa $.$ The rod DB is made of $2050$ aluminum alloy, with a cross$-$sectional area of $300m{m}^2$ and a modulus of elasticity of $70$ GPa. The ABC beam is assumed to be rigid. The system was assembled at $20C,$ and during operation, the temperature rises to $80C.$ Calculate the stresses in the rods under operating conditions. The coefficients of thermal expansion for titanium and aluminum are $8\mathrm{.}5\frac{{10}^{-6}}{}C$ and $24\frac{{10}^{-6}}{}C,$ respectively.