Page 452 - Aircraft Stuctures for Engineering Student

Problems 433

P.10.2 If the web in the wing spar of P.10.1 has a thickness of 2mm and is fully
effective in resisting direct stresses, calculate the maximum value of shear flow in the
web at a section 1 m from the free end of the beam.

Ans. 46.8 N/mm.

P.10.3 Calculate the shear flow distribution and the stringer and flange loads in
the beam shown in Fig. P.10.3 at a section 1.5m from the built-in end. Assume
that the skin and web panels are effective in resisting shear stress only; the beam
tapers symmetrically in a vertical direction about its longitudinal axis.

Am. 913 = q42 = 36.9 N/mm, q35 = 464 = 7.3 N/mm, qZ1 = 96.2 N/mm,
465 = 22.3 N/mm.
P’ = -Pi = 133.3 kN. P4 = P6 = -P3 = -Ps = 66.7kN

250rnm

mrn

Fig. P.10.3

P.10.4 The doubly symmetrical fuselage section shown in Fig. P.10.4 has been
idealized into an arrangement of direct stress carrying booms and shear stress
carrying skin panels; the boom areas are all 150mm’. Calculate the direct stresses
in the booms and the shear flows in the panels when the section is subjected to a
shear load of 50 kN and a bending moment of 100 kN m.
2
Ans. u=,~ = = 180N/mm , uz,2 = a,,lo = = -oz.7 = 144.9N/mm2,
02,3 = oz,g = -o,p = -ffzZ,8 = 60N/m2.
q21 = q65 = 1.9N/mm, q32 = q54 = 12.8 N/mm, q43 = 17.3 N/=,
q67 = ql0 = 11.6 N/mm, q78 = q9 = 22.5 N/mm, qg9 = 27.0 N/mm