Torsion of Non-circular Shafts
Generally for power transmission, circular shafts are used because there is uniform stress distribution along any radius of the shaft. Plane sections of shaft remain plane after the application of twisting moment, as a result there is no distortion in the sections of shafts and change in volume of the shaft is zero.
For stationary torque application, non-circular shafts of different sections such as square, rectangular, triangular, elliptical solid, or hollow are used. The assumption that transverse sections of the shaft remain plane after the applications of torque does not hold good for shaft of non-circular section. Only the lines of symmetry remain straight; all other lines in the section ...