Page 454 - Aircraft Stuctures for Engineering Student

Problems 435

Fig. P.10.7
If this torque were applied at one end and resisted at the other end of such a box of
span 2500mm, find the twist in degrees of one end relative to the other and the
torsional rigidity of the box. The shear modulus G = 26 600 N/mm2 for all walls.

Data:
Shaded areas: A34 = 6450111m', A16 = 775011~~~
Wall lengths: ~3~ = 250mm, $16 = 300mm
Wall thickness: tI2 = 1.63mm, t34 = 0.56mm
t23 = t45 = t56 = 0.92mm
161 = 2.03-
t25 = 2.54mm

Ans. T = 102417Nm, f3 = 1.46", GJ = 10 x 10'2Nmm2/rad.
P.10.8 Determine the torsional stiffness of the four-cell wing section shown in
Fig. P.10.8.
Data:
Wall 12 23 34
78 67 56 45' 45' 36 27 18
Peripheral length (mm) 762 812 812 1525 356 406 356 254
Thickness (mm) 0.915 0.915 0.915 0.711 1.220 1.625 1.220 0.915

Cell areas (mm') AI = 161 500, A11 = 291 000
AI11 291 000, Alv = 226 000
Am. 522.5 x 106GNmm2/rad.

Fig. P.10.8