An Am$1004-$T$61$ magnesium tube is bonded to a central A$36$ steel rod. Sketch and label the shear stress distribution across the entire radius of the composite member when a torque of $4\mathrm{.}8kN*m$ is applied. Sketch the corresponding shear strain distribution.

For the composite member of Problem $4,$ assume that both materials are perfectly plastic once they yield. Furthermore, assume that the shear yield stress of the magnesium is $88$ MPa and the shear yield stress of A $36$ is $140$ MPa $.$ What is the plastic torque for the composite member, i$.$e$.$ the torque when the entire cross section has yielded?

Only need problem $5$ answered.