Page 338 - Aircraft Stuctures for Engineering Student

9.6 Torsion of open section beams 3 19

Fig. 9.37 Warping of an open section beam.

Example 9.8
Determine the maximum shear stress and the warping distribution in the channel
section shown in Fig. 9.38 when it is subjected to an anticlockwise torque of
10 N m. G = 25 000 N/mm'.

From the second of Eqs (9.61) it can be seen that the maximum shear stress occurs
in the web of the section where the thickness is greatest. Also, from the first of Eqs
(9.59)

J = i(2 x 25 x 1S3 + 50 x 2S3) = 316.7mm4
so that
2.5 x io x io3
Tmn = f = &78.9 N/mm'
316.7

Fig. 9.38 Channel section of Example 9.8.