A circular shaft of diameter d and length L is subjected to a torque of T, as show...

A circular shaft of diameter d and length L is subjected to a torque of T, as shown in Fig. 12.24. The shaft is made of 6061-T6 aluminum alloy (see Table D.1), which is assumed to be elastoplastic. Find (a) the radius of the elastic core ; (b) the angle of twist . Given: d = 25 mm, L = 1.2 m, and T = 4.5 KN.m.