고체역학 (Beer) — Torsion: Problem 3.31

3.31 While an oil well is being drilled at a depth of 2500 m, it is observed that the top of the 200-mm-diameter steel drill pipe (\(G = 77.2 \text{ GPa}\)) rotates through 2.5 revolutions before the drilling bit starts to operate. Determine the maximum shearing stress caused in the pipe by torsion.