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392 Stress analysis of aircraft components

10.3.4 Shear centre

The position of the shear centre of a wing section is found in an identical manner to
that described in Section 9.4. Arbitrary shear loads Sx and Sy are applied in turn
through the shear centre S, the corresponding shear flow distributions determined
and moments taken about some convenient point. The shear flow distributions are
obtained as described previously in the shear of multicell wing sections except that
the N equations of the type (10.28) are sufficient for a solution since the rate of
twist de/& is zero for shear loads applied through the shear centre.

10.3.5 Tapered wings

Wings are generally tapered in both spanwise and chordwise directions. The effects on
the analysis of taper in a single cell beam have been discussed in Section 10.1. In a
multicell wing section the effects are dealt with in an identical manner except that
the moment equation (10.16) becomes, for an N-cell wing section (see Figs 10.5
and 10.22)

Example 10.9
A two-cell beam has singly symmetrical cross-sections 1.2 m apart and tapers symme-
trically in the y direction about a longitudinal axis (Fig. 10.26). The beam supports
loads which produce a shear force Sy = lOkN and a bending moment

1 1

Fig. 10.26 Tapered beam of Example 10.9.