Ok so every time I do a fatigue problem, I do it completely differently from the way the solution has it. I tried #19 in Lindeburg's Practice problems which is as follows:
Circular tube, .5in OD, .03 in wall thickness, alternating stresses -3in-lbf and 30in-lbf. 42kpsi Sy, 72kpsi Sult, 24k...