Diagram shows a shaft with brass segment A B of length 1800 millimeters which is connected to aluminum segment B C of length 800 millimeter using a flange at B and a torque T of 50 Newton meter is applied on C. The x axis is taken along the axis of the cylinders and the y axis is taken along the rigid support at A and perpendicular to the x axis.

A single torque of T= 50 N-m is applied to a compound torsion member. Segment (1) is a 32-mm diameter solid brass (G=37 GPa) rod. Segment (2) is a solid aluminum (G=26 GPa) rod.

Determine the minimum diameter of the aluminum segment if the rotation angle at C relative to support A must not exceed 3°.