Two solid steel shafts are fitted with flanges that are then connected by bolts as shown. The bolts are slightly undersized and permit a $1\mathrm{.}5$ rotation of one flange with respect to the other before the flanges begin to rotate as a single unit.

Knowing that G $=77\mathrm{.}2$ GPa, determine the maximum shearing stress in each shaft when a torque $T$ of magnitude $480N*m$ is applied to$.$ flange $B.$

Answers:

$[67\mathrm{.}3$ MPa in shaft AB; $13\mathrm{.}44$ MPa in shaft BC$]$ but i need to know how to get there