Page 476 - Aircraft Stuctures for Engineering Student

11.4 Shear lag 457

L
Fig. 11.12 Topcoverof the beamof Fig. 11.10.
central boom need be considered as long as the symmetry is allowed for in the
assumed directions of the panel shear flows q, as shown in Fig. 11.12. Further, the
origin for z may be taken to be at either the free or built-in end. A marginally simpler
solution is obtained if the origin is taken to be at the free end, in which case the
solution represents that for an infinitely long panel. Considering the equilibrium of
an element of an edge boom (Fig. 11.13), in which we assume that the boom load
is positive (tension) and increases with increasing z, we have

or

(1 1.24)

Similarly, for an element of the central boom (Fig. 11.14)
aPA
-+2q=o (1 1.25)
dZ
Now considering the overall equilibrium of a length z of the cover (Fig. 11.15), we have

-0
2PB + PA +-z SY - (1 1.26)
h

Fig. 11 .I3 Equilibrium of boom element.