고체역학 (Beer) — Torsion: Problem 3.135

3.135 A 1.25-m-long steel angle has an L127 × 76 × 6.4 cross section. From Appendix E we find that the thickness of the section is 6.4 mm and that its area is 1250 mm². Knowing that τall = 60 MPa and that G = 77.2 GPa, and ignoring the effect of stress concentrations, determine (a) the largest torque T that can be applied, (b) the corresponding angle of twist.