Page 461 - Aircraft Stuctures for Engineering Student

442 Stress analysis of aircraft components

shear flows in the spar webs and remaining skin panels, the distribution of load in the
spar flanges and the loading on the central rib. Assume that the spar webs and skin
panels are effective in resisting shear stresses only.
q
in
Ans. Bay (iJ spar webs = 7.5 N/mm
:
Bay @ : q in spar webs = 1.9 N/mm, in skin panels = 9.4 N/mm
Flange loads (2): at built-in end = 1875 N (compression)
at central rib = 5625 N (compression)
Rib loads: q (horizontal edges) = 9.4 N/mm,
q (vertical edges) = 9.4 N/mm

P.10.20 A bar, whose cross-section is shown in Fig. P.10.20, comprises a
polyester matrix and Kevlar filaments; the respective moduli are 3000 N/mm2 and
140000N/mm2 with corresponding Poisson’s ratios of 0.16 and 0.28. If the bar is
lm long and is subjected to a compressive axial load of 500kN, determine the
shortening of the bar, the increase in its thickness and the stresses in the polyester
and Kevlar.
Ans. 3.26mm, 0.032 mm, 9.78 N/mm2, 456.4N/mm2

I Timm
polyester

polyester
Kevlar
polyester

Fig. P.10.20.