고체역학 (Beer) — Pure Bending: Problem 4.26

4.26 A thick-walled pipe is bent about a horizontal axis by a couple M. The pipe may be designed with or without four fins. (a) Using an allowable stress of 20 ksi, determine the largest couple that may be applied if the pipe is designed with four fins as shown. (b) Solve part a, assuming that the pipe is designed with no fins.