Question $4[32$ Marks$]$

Consider the composite shaft in figute Q$4.$ The inner diameter of the $18$ mm thick

hollow shaft $BC$ is equal to the diameter of the solid shafts $(AB$ and $CD.$ The solid

shafts $AB$ and $CD$ have the same diameter. The maximum shear stress in shaft $AB$ is

$10\mathrm{.}2$ MPa

Determine the following

the minimum and naximum shear stress in the hollow shaft $($BC$)$

the maximum sheat stress ili shati CD

total angle of ivist of the compound shatl $)$