고체역학 (Beer) — Torsion: Problem 3.54

3.54 The composite shaft shown is to be twisted by applying a torque $T$ at end $A$. Knowing that the modulus of rigidity is $11.2 \times 10^6$ psi for steel and $4 \times 10^6$ psi for aluminum, determine the largest angle through which end $A$ may be rotated, if the following allowable stresses are not to be exceeded: $\tau_{steel} = 8000$ psi and $\tau_{aluminum} = 6000$ psi.