Page 505 - Aircraft Stuctures for Engineering Student

486 Structural constraint
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P.ll.l A thin-walled beam with the singly symmetrical cross-section shown in
Fig. P.11.1, is built-in at one end where the shear force Sy = 11 1 250 N is applied
through the web 25. Assuming the cross-section remains undistorted by the loading,
determine the shear flow and the position of the centre of twist at the built-in end. The
shear modulus G is the same for all walls.

Ans. q12 = q56 = 46.6 N/mm, 952 = 180.8 N/mm,
932 = q54 = 1.4N/mm1 q43 = 74.6N/mm7
XR = -630.1 mm, YR = 0 (relative to mid-point of 52)

127

I27

I.
' 305mm I 254 mmq
Fig. P.ll.l

P.11.2 I thin-walled two-cell beam with the singly symmetrica, cross-section
shown in Fig. P. 1 1.2 is built-in at one end where the torque is 1 1 000 N m. Assuming
the cross-section remains undistorted by the loading, determine the distribution of
shear flow and the position of the centre of twist at the built-in end. The shear
modulus G is the same for all walls.
1.2 mm
I

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Fig. P.11.2