Introduction to Aircraft Structural Analysis (Elsevier Aerospace Engineering)

542 CHAPTER 19 Structural Idealization

Fig.19.5

Idealized fuselage section of Example 19.2.

The origin of axes Cxycoincides with the position of the centroid of the direct stress-carrying area,
which,inthiscase,isthecentroidoftheboomareas.Thus,takingmomentsofareaaboutboom9,

( 6 × 640 + 6 × 600 + 2 × 620 + 2 × 850 )y

= 640 × 1200 + 2 × 600 × 1140 + 2 × 600 × 960 + 2 × 600 × 768

+ 2 × 620 × 565 + 2 × 640 × 336 + 2 × 640 × 144 + 2 × 850 × 38

whichgives

y=540mm

ThesolutionisnowcompletedinTable19.1
Fromcolumn④

Ixx= 1854 × 106 mm^4

andcolumn⑤iscompletedusingEq.(i).

19.3.2 Shear of Open Section Beams

The derivation of Eq. (16.14) for the shear flow distribution in the cross section of an open section
beamisbasedontheequilibriumequation(16.2).Thethicknesstinthisequationreferstothedirect