**V. COMBINED
TRANSVERSE
SHEAR,**

BENDING, AND
TORSION
LOADING

The problems of combined loading are fairly common in aircraft structures. For
example, if we consider the aerodynamic loads acting on a wing. We realize that
in many cases the line of aerodynamic centers does not coincide with the elastic
axis (i.e., the line passing through the shear center of every spanwise section
of the
wing). As a result the wing bending will be combined with twisting action as
well. So in this case the loads at the aerodynamic center line can be replaced
with an equivalent force couple system acting at the elastic axis. The force
component will produce transverse shear loading and bending moment along the
length of the wing while the couple produces a torque.
The example problem below is taken from the previous section and it basically
highlights the procedure for analyzing such problems in general.
One must keep in mind that depending upon the complexity of the beam cross
section the bending and shear stresses may require the use of general bending
stress and general shear flow equations.
In addition to the loadings stated earlier it may be possible to have axial
tension as well. The rotating wing problem (i.e., helicopter blade) is a
good example of such a problem.

EXAMPLE
PROBLEMS

- Example 1 Analysis of a two-cell
multiple flange box beam

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Transverse Shear Loading of Closed Sections
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Internal Pressure