Page 455 - Aircraft Stuctures for Engineering Student

436 Stress analysis of aircraft components

P.10.9 Determine the shear flow distribution for a torque of 56 500 N m for the
three cell section shown in Fig. P.10.9. The section has a constant shear modulus
throughout.

Wall Length (mm) Thickness (mm) Cell Area (mm')
~ ~~
12" 1084 1.220 I 108400
1 2L 2160 1.625 I1 202 500
14,23 127 0.915 I11 528 000
34u 797 0.915
34L 797 0.915

Ans. qI2u = 25.4N/mm, = 33.5N/mm, 914 = q32 = 8.1N/mm,
q43u = 13.4N/m~i, q34~ = ~.~N/IIUJI

Fig. P.10.9

P.10.10 The idealized cross-section of a two-cell thin-walled wing box is shown in
Fig. P.10.10. If the wing box supports a load of 44500N acting along the web 25,
calculate the shear flow distribution. The shear modulus G is the same for all walls
of the wing box.

~~
Wall Length (mm) Thickness (mm) Boom Area (mm2)
_____
~ ~~ ~
16 254 1.625 1. 6 1290
25 406 2.032 2, 5 1936
34 202 1.220 334 645
12,56 641 0.915
23,45 175 0.559
Cell areas: AI = 232 000 mm2, ,411 = 258 000 mm2

Ans. q16 = 33.9N/m, q65 = 421 = 1.1 N/IIUn,
q45 = q23 = 7.2N/mm, q34 = 20.8 N/mm,
q25 = 73.4N/mm