(Solved): 16 A uniform steel rod of cross-sectional area A is attached to rigid supports and is unstressed a ...

16 A uniform steel rod of cross-sectional area $A$ is attached to rigid supports and is unstressed at a temperature of $45^{?}\mathrm{F}$. The steel is assumed to be elastoplastic with ${?}_Y=36\mathrm{ksi}$ and $E=29\times 10^6$ psi. Knowing that $?=6.5\times 10^{?6}/{}^{?}\mathrm{F}$, determine the stress in the bar $(a)$ when the temperature is raised to $320^{?}\mathrm{F},($ b) after the temperature has returned to $45^{?}\mathrm{F}$. Fig. P2.116