I received the following question about problem 7.13 via email:
Q: The appendix does not describe how circular shafts load behave under tension, bending and torsion at the same time. Where/how am I supposed to get this information?
A: As we've discussed on a couple of problems, you can take the individual stresses determined from each loading case and combine them to give the stresses in the combined loading case. You will need to use information from both Figure A.1 and Figure A.2. In Figure A.1, although different shapes are shown in the illustrations, the equations are general and not shape specific. Thus, tension loading is shown in (a), bending in (b), and torsion in (c). In each case, you will need to substitute specific expressions for area, A, area moment of inertia, Iz, and angular moment of inertia, J, from Figure A.2 (b), which provides A, Iz, and J specifically for a solid circular shaft cross-section.
-- Dr. VanLandingham