Three identical circular disks A, B, and C are welded to the ends of three identical solid circular bars (see figure). The bars lie in a common plane and the disks lie in planes perpendicular to the axes of the bars. The bars are welded at their intersection D to form a rigid connection. Each bar has diameter d1 = 0.5 in. and each disk has diameter d2 = 3.0 in.
Forces P1, P2, and P3 act on disks A, B, and C, respectively, thus subjecting the bars to torsion. If P1 = 28 lb, what is the maximum shear stress max in any of the three bars?

Pi 135 P3 350 Pi 90 P2 P2