Page 456 - Aircraft Stuctures for Engineering Student

Problems 437

44500 N

I II

1 1

Fig. P.lO.10

P.10.11 Figure P. 10.11 shows a singly symmetric, two-cell wing section in which
all direct stresses are carried by the booms, shear stresses alone being carried by the
walls. All walls are flat with the exception of the nose portion 45. Find the position of
the shear centre S and the shear flow distribution for a load of S, = 66 750 N through
S. Tabulated below are lengths, thicknesses and shear moduli of the shear carrying
walls. Note that dotted line 45 is not a wall.

Wall Length (mm) Thickness (mm) G (N/mm2) Boom Area (mrn')
34, 56 380 0.915 20 700 1, 3, 6, 8 1290
12.23,61,18 356 0.915 24 200 2,4, 5: 1 645
36,81 306 1.220 24 800
45 610 1.220 24 800
Nose area N, = 51 500mm'

4 3 3
153 ' mm
-
x
X\WN+- - -- + ___- ---- --- +--I--
I53 mm

Fig. P.10.11
P.10.12 A singly symmetric wing section consists of two closed cells and one
open cell (see Fig. P.10.12). The webs 25, 34 and the walls 12, 56 are straight, while
all other wdls are curved. All walls of the section are assumed to be effective in
carrying shear stresses only, direct stresses being carried by booms 1 to 6. Calculate