Q$1.25\%$ a$)$ A steel open$-$ended cylindrical tube is subjected to an internal pressure

of $P_i.$ Compute the stresses ${}_r,{}_t,{}_l,$ and ${}_{\text{m}\text{a}\text{x}}$ at the inner and outer surfaces of the

tube as well as at mid wall thickness $r=45mm.$ Data are as follows:

$E=200$GPa,$d_i=80mm,d_o=100mm,P_i=20$MPa

b$)$ If the internally pressurized tube in Part $($a$)$ is not one integral piece of material,

but composed of two concentric tubes of the same material press$-$fitted to each other

with a radial interference of $72m,$ calculate the stresses ${}_r,$ and ${}_t$ at the inner and

outer surfaces of both tubes. Data are as follows:

$E=200$GPa,$d_{\text{i}\text{i}\text{n}\text{n}\text{e}\text{r}}=80mm,d_{o\text{i}\text{n}\text{n}\text{e}\text{r}}=90mm,$

$d_{\text{i}\text{o}\text{u}\text{t}\text{e}\text{r}}=90mm,d_{o\text{o}\text{u}\text{t}\text{e}\text{r}}=100mm,P_i=20$MPa